Question: what is known about those infected with Covid-19 but are asymptomatic?

Title: A systematic review of asymptomatic infections with COVID-19 Content: Since the outbreak of coronavirus disease 2019 (COVID-19) in late December 2019, it has brought significant harm and challenges to over 200 countries and regions around the world. However, there is increasing evidence that many patients with COVID-19 are asymptomatic or have only mild symptoms, but they are able to transmit the virus to others. There are difficulties in screening for asymptomatic infections, which makes it more difficult for national prevention and control of this epidemic. This article reviews the characteristics, treatment, and outcomes of asymptomatic infections with COVID-19, hoping it would be helpful for early prevention and control of this severe public health threat worldwide.

Title: A Systematic Review of Asymptomatic Infections with COVID-19 Content: Since the outbreak of coronavirus disease 2019 (COVID-19) in late December 2019, it has brought significant harm and challenges to over 200 countries and regions around the world. However, there is increasing evidence that many patients with COVID-19 are asymptomatic or have only mild symptoms, but they are able to transmit the virus to others. There are difficulties in screening for asymptomatic infections, which makes it more difficult for national prevention and control of this epidemic. This article reviews the characteristics, treatment, and outcomes of asymptomatic infections with COVID-19, hoping it would be helpful for early prevention and control of this severe public health threat worldwide.

Title: Asymptomatic patients and asymptomatic phases of Coronavirus Disease 2019 (COVID-19): a population-based surveillance study Content: In this population-based study, we identified 307 confirmed COVID-19 cases from massive surveillance, including 129,551 individuals screened at fever clinics or returning from Hubei and 3710 close contacts of confirmed COVID-19 patients. Among them, 17 patients were asymptomatic at initial clinical assessment. These asymptomatic patients on admission accounted for a small proportion of all patients (5.54%) with relatively weak transmissibility, and the detection rate was 0.35 per 100 close contacts. Moreover, the dynamics of symptoms of the 307 patients showed that the interval from symptom remission to the final negativity of viral nucleic acid was 5.0 days (IQR 2.0 to 11.0 days), with 14 patients (4.56%) having re-detectable viral RNA after discharge. Together, our findings suggested asymptomatic carriers and presymptomatic patients only accounted for a small proportion of COVID-19. Also, the asymptomatic phase in during recovery of COVID-19 urged that negativity in viral RNA is necessary as de-isolation criteria and follow-up is recommended.

Title: Prevention of COVID-19 infection in the medical population: a possible help from anosmia? Content: COVID-19 asymptomatic cases increases the risks of disease dissemination with even greater risk for physicians given the shortage of personal protective equipment. Here we report on the consistent finding of frequent presentation of anosmia or hyposmia in COVID-19 patients, even in the absence of other symptoms and without other olfactory or nasal findings. In the uncertainty of the clinical characteristics of these patients, this symptom can be a tool to reduce the spread of the infection between medical population.

Title: Prevention of COVID-19 infection in the medical population: a possible help from anosmia?. Content: COVID-19 asymptomatic cases increases the risks of disease dissemination with even greater risk for physicians given the shortage of personal protective equipment. Here we report on the consistent finding of frequent presentation of anosmia or hyposmia in COVID-19 patients, even in the absence of other symptoms and without other olfactory or nasal findings. In the uncertainty of the clinical characteristics of these patients, this symptom can be a tool to reduce the spread of the infection between medical population.

Title: There are asymptomatic and pre-symptomatic patients infected with COVID-19. So what? Pandemic response implications Content: Abstract Asymptomatic but infectious people have been reported in many infectious diseases. Asymptomatic and pre-symptomatic carriers would be a hidden reservoir of COVID-19. Aim This review identifies primary empirical evidence about the ability of asymptomatic carriers to infect others with COVID-19 pandemic and reflects on the implications for control measures. Methods A systematic review is followed by a narrative report and commentary inclusion criteria were: studies reporting primary data on asymptomatic or pre-symptomatic patients, who were considered to have passed on COVID-19 infection; and published in indexed journals or in peer review between January 1 and March 31, 2020. Results Nine articles reported on 83 asymptomatic or pre-symptomatic persons. Conclusions The evidence confirms COVID-19 transmission from people who were asymptomatic at the time. A series of implications for health service response are laid out. Keywords: Covid-19, Asymptomatic, Pre-symptomatic, Public Health

Title: [Advances on presymptomatic or asymptomatic carrier transmission of COVID-19] Content: COVID-19 is rapidly spreading. Patients in incubation period and healthy carriers are possible sources for transmission. However, such sources of infection cannot be effectively identified due to the symptoms absent. The research evidence is very lacking so far, although there are a few studies suggesting that presymptomatic or asymptomatic carrier may cause COVID-19 transmission. Nearly half of the literature is in the state of preprint without peer review. The question of "the degree to which presymptomatic or asymptomatic infections can transmit" is not fully understood. There is an urgent need to screen infected carriers in larger close contacts or in the general population, and assess their risk for transmission.

Title: [Advances on presymptomatic or asymptomatic carrier transmission of COVID-19]. Content: COVID-19 is rapidly spreading. Patients in incubation period and healthy carriers are possible sources for transmission. However, such sources of infection cannot be effectively identified due to the symptoms absent. The research evidence is very lacking so far, although there are a few studies suggesting that presymptomatic or asymptomatic carrier may cause COVID-19 transmission. Nearly half of the literature is in the state of preprint without peer review. The question of "the degree to which presymptomatic or asymptomatic infections can transmit" is not fully understood. There is an urgent need to screen infected carriers in larger close contacts or in the general population, and assess their risk for transmission.

Title: Viral dynamics in asymptomatic patients with COVID-19 Content: Data are limited on the viral load, viral shedding patterns, and potential infectivity of asymptomatic patients (APs) with coronavirus disease 2019 (COVID-19). This study included 31 adult patients who were virologically confirmed to have COVID-19 but were asymptomatic on admission. Among these 31 patients, 22 presented symptoms after admission and were defined as asymptomatic patients in the incubation period (APIs); the other nine patients remained asymptomatic during hospitalization and were defined as asymptomatic patients (APs). The median cycle threshold (Ct) value of APs (39.0, interquartile range (IQR) 37.5-39.5) was significantly higher than that of APIs (34.5, IQR 32.2-37.0), indicating a lower viral load in APs. However, the duration of viral shedding remained similar in the two groups (7 days, IQR 5-14 days vs. 8 days, IQR 5-16 days). The study findings demonstrated that although APs with COVID-19 have a lower viral load, they still have certain period of viral shedding, which suggests the possibility of transmission during their asymptomatic period. Further longitudinal surveillance of these asymptomatic cases via virus nucleic acid testing are warranted.

Title: The incidence of the novel coronavirus SARS-CoV-2 among asymptomatic patients: a systematic review Content: BACKGROUND: the recent outbreak of the coronavirus disease 2019 (COVID‐19) has quickly spread globally since its discovery in Wuhan, China, in December 2019. A comprehensive strategy, including surveillance, diagnostics, research, and clinical treatment is urgently needed to win the battle against COVID-19. Recently, numerous studies reported the incidence of SARS-CoV-2 in asymptomatic patients. Yet, the incidence and viral transmission from the asymptomatic cases are not apparent yet. AIM: this study aims to systematically review the published literature on SARS-CoV-2 in the asymptomatic patients to estimate the incidence of COVID-19 among asymptomatic cases, as well as describe its epidemiological and clinical significance. METHOD: the literature was searched through four scientific databases: PubMed, Web of Science, Scopus, and Science Direct. RESULTS: a total of 63 studies satisfied the inclusion criteria where the majority of the reported studies were from China. However, there was a lack of SARS-CoV-2 epidemiological studies from several countries worldwide, tracing the actual incidence of COVID-19, especially in asymptomatic patients. Studies with a large sample size (n>1000) estimated that percentage of people contracting SARS-CoV-2 and are likely to be asymptomatic ranges from 1.2-12.9%. However, the other studies with a smaller sample size reported a much higher incidence and indicated that up to 87.9% of COVID-19 infected individuals could be asymptomatic. Most of these studies indicated that asymptopatics are a potential source of infection to the community. CONCLUSION: this review highlighted the need for more robust and well-designed studies to better estimate COVID-19 incidence among asymptomatic patients worldwide. The early identification of the asymptomatic cases, as well as monitoring and tracing close contact, could help in mitigating the spread of COVID-19.

Title: Viral dynamics in asymptomatic patients with COVID-19 Content: Abstract Data are limited on the viral load, viral shedding patterns and potential infectivity of asymptomatic patients (APs) with coronavirus disease 2019 (COVID-19). We included 31 adult patients who were virologically confirmed to have COVID-19 but were asymptomatic on admission. Among these 31 patients, 22 presented symptoms after admission and were defined as asymptomatic patients in incubation period (APIs); the other 9 patients remained asymptomatic during hospitalization and were defined as asymptomatic patients (APs). The cycle threshold (Ct) values of APs (39.0, IQR 37.5-39.5) was significantly higher than those of APIs (34.5, IQR 32.2-37.0), which indicated a lower viral load in APs, but the duration of viral shedding remained similar between the two groups (7 days IQR 5-14 vs. 8 days IQR 5-16). The study findings demonstrated that although they have a lower viral load, APs with COVID-19 still have certain period of viral shedding, which suggests the possibility of transmission during their asymptomatic period. Further longitudinal surveillance of these asymptomatic cases via virus nucleic acid tests are warranted.

Title: The incidence of the novel coronavirus SARS-CoV-2 among asymptomatic patients: a systematic review Content: BACKGROUND: the recent outbreak of the coronavirus disease 2019 (COVID-19) has quickly spread globally since its discovery in Wuhan, China, in December 2019. A comprehensive strategy, including surveillance, diagnostics, research, and clinical treatment is urgently needed to win the battle against COVID-19. Recently, numerous studies reported the incidence of SARS-CoV-2 in asymptomatic patients. Yet, the incidence and viral transmission from the asymptomatic cases are not apparent yet. AIM: this study aims to systematically review the published literature on SARS-CoV-2 in the asymptomatic patients to estimate the incidence of COVID-19 among asymptomatic cases, as well as describe its epidemiological and clinical significance. METHOD: the literature was searched through four scientific databases: PubMed, Web of Science, Scopus, and Science Direct. RESULTS: a total of 63 studies satisfied the inclusion criteria where the majority of the reported studies were from China. However, there was a lack of SARS-CoV-2 epidemiological studies from several countries worldwide, tracing the actual incidence of COVID-19, especially in asymptomatic patients. Studies with a large sample size (n>1000) estimated that percentage of people contracting SARS-CoV-2 and are likely to be asymptomatic ranges from 1.2-12.9%. However, the other studies with a smaller sample size reported a much higher incidence and indicated that up to 87.9% of COVID-19 infected individuals could be asymptomatic. Most of these studies indicated that asymptopatics are a potential source of infection to the community. CONCLUSION: this review highlighted the need for more robust and well-designed studies to better estimate COVID-19 incidence among asymptomatic patients worldwide. The early identification of the asymptomatic cases, as well as monitoring and tracing close contact, could help in mitigating the spread of COVID-19.

Title: Asymptomatic patients as a source of COVID-19 infections: A systematic review and meta-analysis Content: BACKGROUND: Coronavirus Disease 2019 (COVID-19) is characterised by an unpredictable disease course, ranging from asymptomatic infections to severe, life-threating manifestations. Asymptomatic COVID-19 infections have been described, and the aim of this systematic review was to summarise their presentation form. METHODS: We searched PubMed® and Google® (1 December 2019 to 29 March 2020) and extracted age, laboratory findings, and computed tomography (CT) investigations. Pooled incidence rates of clinical characteristics were analysed using random effects models. RESULTS: In total, 506 patients from 34 studies (68 single cases and 438 from case series) with an asymptomatic course were identified. Patients with normal radiology were younger (19.59 ± 17.17 years) than patients with abnormal radiology (39.14 ± 26.70 years) (p value = 0.013). Despite being asymptomatic, CT investigations revealed abnormalities in 62.2% of the cases and ground glass opacities were most frequently observed (43.09% by meta-analysis). Most studies reported normal laboratory findings (61.74% by meta-analysis). CONCLUSIONS: More than half of patients without any symptoms present with CT abnormalities. Asymptomatic patients may be contagious and thus a potential source of transmission of COVID-19.

Title: How the asymptomatic population is influencing the COVID-19 outbreak in India? Content: According to the current perception, symptomatic, presymptomatic, and asymptomatic infectious persons can infect the healthy population susceptible to the SARS-Cov-2. More importantly, various reports indicate that the number of asymptomatic cases can be several-fold higher than the reported symptomatic cases. In this article, we take the reported cases in India and various states within the country as the specimen to understand the progression of the COVID-19. Employing a modified SEIRD model, we predict the spread of COVID-19 by the symptomatic as well as asymptomatic infectious population. Considering reported infection primarily due to symptomatic we compare the model predicted results with the available data to estimate the dynamics of the asymptomatically infected population. Our data indicate that in the absence of the asymptomatic infectious population, the number of symptomatic cases would have been much less. Therefore, the current progress of the symptomatic infection can be reduced by quarantining the asymptomatically infectious population via extensive or random testing. This study is motivated strictly towards academic pursuit; this theoretical investigation is not meant for influencing policy decisions or public health practices.

Title: Asymptomatic patients as a source of COVID-19 infections: A systematic review and meta-analysis. Content: BACKGROUND Coronavirus Disease 2019 (COVID-19) is characterised by an unpredictable disease course, ranging from asymptomatic infections to severe, life-threating manifestations. Asymptomatic COVID-19 infections have been described, and the aim of this systematic review was to summarise their presentation form. METHODS We searched PubMed® and Google® (1 December 2019 to 29 March 2020) and extracted age, laboratory findings, and computed tomography (CT) investigations. Pooled incidence rates of clinical characteristics were analysed using random effects models. RESULTS In total, 506 patients from 34 studies (68 single cases and 438 from case series) with an asymptomatic course were identified. Patients with normal radiology were younger (19.59 ± 17.17 years) than patients with abnormal radiology (39.14 ± 26.70 years) (p value = 0.013). Despite being asymptomatic, CT investigations revealed abnormalities in 62.2% of the cases and ground glass opacities were most frequently observed (43.09% by meta-analysis). Most studies reported normal laboratory findings (61.74% by meta-analysis). CONCLUSIONS More than half of patients without any symptoms present with CT abnormalities. Asymptomatic patients may be contagious and thus a potential source of transmission of COVID-19.

Title: Challenges of managing the asymptomatic carriers of SARS-CoV-2 Content: After an outbreak in Wuhan, China, a growing number of countries are now suffering from an epidemic by SARS-CoV-2, which causes COVID-19. Undoubtedly, reports of the skyrocketing global spread of COVID-19 has shocked people globally, from Japan to the United States. Presently, the World Health Organization indicates that the fatality rate due to COVID-19 is about 2%, inferring that many positive subjects may potentially overcome the illness with mild influenza-like symptoms and no need for hospitalization at intensive-care units. Because COVID-19 is completely new to the human immune system, many throughout the world are likely vulnerable to becoming sick after their initial exposure to SARS-CoV-2. Besides hospitalized cases, many individuals are likely asymptomatic but potentially carry the virus. While our knowledge about carriers and their virus shedding is deficient, some studies modelling the viral transmission have considered the potential contribution of the asymptomatic carriers. Protocols for managing asymptomatic cases, for example for controlling them to restrict their contact with healthy people at public places or private residences, have not been established. In-house quarantine may as well be applicable to asymptomatic cases if they could be identified and diagnosed. Presumably now, the asymptomatic subjects potentially contribute to the transmission of COVID-19 without their knowledge, intention, or being diagnosed as carriers. Thus, managing the asymptomatic subjects, who can carry and likely transmit the virus, is a major healthcare challenge while the pandemic is looming.

Title: Clinical characteristics of 24 asymptomatic infections with COVID-19 screened among close contacts in Nanjing, China Content: Previous studies have showed clinical characteristics of patients with the 2019 novel coronavirus disease (COVID-19) and the evidence of person-to-person transmission. Limited data are available for asymptomatic infections. This study aims to present the clinical characteristics of 24 cases with asymptomatic infection screened from close contacts and to show the transmission potential of asymptomatic COVID-19 virus carriers. Epidemiological investigations were conducted among all close contacts of COVID-19 patients (or suspected patients) in Nanjing, Jiangsu Province, China, from Jan 28 to Feb 9, 2020, both in clinic and in community. Asymptomatic carriers were laboratory-confirmed positive for the COVID-19 virus by testing the nucleic acid of the pharyngeal swab samples. Their clinical records, laboratory assessments, and chest CT scans were reviewed. As a result, none of the 24 asymptomatic cases presented any obvious symptoms while nucleic acid screening. Five cases (20.8%) developed symptoms (fever, cough, fatigue, etc.) during hospitalization. Twelve (50.0%) cases showed typical CT images of ground-glass chest and 5 (20.8%) presented stripe shadowing in the lungs. The remaining 7 (29.2%) cases showed normal CT image and had no symptoms during hospitalization. These 7 cases were younger (median age: 14.0 years; P=0.012) than the rest. None of the 24 cases developed severe COVID-19 pneumonia or died. The median communicable period, defined as the interval from the first day of positive nucleic acid tests to the first day of continuous negative tests, was 9.5 days (up to 21 days among the 24 asymptomatic cases). Through epidemiological investigation, we observed a typical asymptomatic transmission to the cohabiting family members, which even caused severe COVID-19 pneumonia. Overall, the asymptomatic carriers identified from close contacts were prone to be mildly ill during hospitalization. However, the communicable period could be up to three weeks and the communicated patients could develop severe illness. These results highlighted the importance of close contact tracing and longitudinally surveillance via virus nucleic acid tests. Further isolation recommendation and continuous nucleic acid tests may also be recommended to the patients discharged. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s11427-020-1661-4 and is accessible for authorized users.

Title: Estimating the extent of true asymptomatic COVID-19 and its potential for community transmission: systematic review and meta-analysis Content: Background: The prevalence of true asymptomatic COVID-19 cases is critical to policy makers considering the effectiveness of mitigation measures against the SARS-CoV-2 pandemic. We aimed to synthesize all available research on the asymptomatic rates and transmission rates where possible. Methods: We searched PubMed, Embase, Cochrane COVID-19 trials, and European PMC for pre-print platforms such as MedRxiv. We included primary studies reporting on asymptomatic prevalence where: (a) the sample frame includes at-risk population, and (b) there was sufficiently long follow up to identify pre-symptomatic cases. Meta-analysis used fixed effect and random effects models. Results: We screened 571 articles and included five low risk-of-bias studies from three countries (China (2), USA (2), Italy (1)) that tested 9,242 at-risk people, of which 413 were positive and 65 were asymptomatic. Diagnosis in all studies was confirmed using a RT-qPCR test. The proportion of asymptomatic cases ranged from 6% to 41%. Meta-analysis (fixed effect) found that the proportion of asymptomatic cases was 16% (95% CI: 12% - 20%) overall; higher in non-aged care 19% (15% - 24%), and lower in long-term aged care 8% (4% - 14%). Two studies provided direct evidence of forward transmission of the infection by asymptomatic cases but suggested lower rates than symptomatic cases. Conclusion: Our estimates of the prevalence of asymptomatic COVID-19 cases are lower than many highly publicized studies, but still substantial. Further robust epidemiological evidence is urgently needed, including in sub-populations such as children, to better understand the importance of asymptomatic cases for driving spread of the pandemic.

Title: Asymptomatic transmission and the infection fatality risk for COVID-19: Implications for school reopening Content: Asymptomatic infection occurs for numerous respiratory viral diseases, including influenza and COVID-19. We seek to clarify confusion in three areas: age-specific risks of transmission and/or disease; various definitions for the COVID-19 “mortality rate”, each useful for specific purposes; and implications for student return strategies from pre-school through university settings.

Title: Asymptomatic transmission and the infection fatality risk for COVID-19: Implications for school reopening Content: Asymptomatic infection occurs for numerous respiratory viral diseases, including influenza and COVID-19. We seek to clarify confusion in three areas: age-specific risks of transmission and/or disease; various definitions for the COVID-19 "mortality rate", each useful for specific purposes; and implications for student return strategies from pre-school through university settings.

Title: COVID-19: asymptomatic carrier transmission is an underestimated problem Content: At the present time, COVID-19 is spreading rapidly [1]. The global prevention and control of COVID-19 is focused on the estimation of the relevant incubation period, basic reproduction number (R(0)), effective reproduction number (R(t)) and death risk. Although the prevention and control of COVID-19 requires a reliable estimation of the relevant incubation period, R(0), R(t) and death risk. Another key epidemiological parameter-asymptomatic ratio that provides strength and range for social alienation strategies of COVID-19, which is widely defined as the proportion of asymptomatic infections among all disease infections. In fact, the ratio of asymptomatic infection is a useful indicator of the burden of disease and a better measurement of the transmissibility of the virus. So far, people have not paid enough attention to asymptomatic carriers. The asymptomatic carriers discussed in this study are recessive infections, that is, those who have never shown symptoms after onset of infection. We will discuss three aspects: detection, infectivity and proportion of healthy carriers.

Title: Clinical Progression of COVID-19 Patient with Extended Incubation Period, Delayed RT-PCR Time-to-positivity, and Potential Role of Chest CT-scan Content: Coronavirus Disease 2019 (COVID-19), previously called 2019-nCoV, is a novel disease caused by SARS- CoV-2 which was first identified as outbreak of unknown respiratory illness in Wuhan, China. COVID- 19 was declared as global health emergency by WHO on March 11, 2020 and quickly elevated to global pandemic on 11 March 2020. COVID-19 symptom is highly various in each patient, with fever, fatigue, shortness of breath, and cough as the main presenting symptoms. Patient with COVID-19 may shows severe symptom with severe pneumonia and ARDS, mild symptom resembling simple upper respiration tract infection, or even completely asymptomatic. Approximately 80% of cases is mild. However the number may changes as more people are getting tested. Some experts are estimating that up to 50% of all cases may be asymptomatic carrier.

Title: Clinical Progression of COVID-19 Patient with Extended Incubation Period, Delayed RT-PCR Time-to-positivity, and Potential Role of Chest CT-scan. Content: Coronavirus Disease 2019 (COVID-19), previously called 2019-nCoV, is a novel disease caused by SARS- CoV-2 which was first identified as outbreak of unknown respiratory illness in Wuhan, China. COVID- 19 was declared as global health emergency by WHO on March 11, 2020 and quickly elevated to global pandemic on 11 March 2020. COVID-19 symptom is highly various in each patient, with fever, fatigue, shortness of breath, and cough as the main presenting symptoms. Patient with COVID-19 may shows severe symptom with severe pneumonia and ARDS, mild symptom resembling simple upper respiration tract infection, or even completely asymptomatic. Approximately 80% of cases is mild. However the number may changes as more people are getting tested. Some experts are estimating that up to 50% of all cases may be asymptomatic carrier.

Title: COVID-19: asymptomatic carrier transmission is an underestimated problem Content: At the present time, COVID-19 is spreading rapidly [1]. The global prevention and control of COVID-19 is focused on the estimation of the relevant incubation period, basic reproduction number (R0), effective reproduction number (Rt) and death risk. Although the prevention and control of COVID-19 requires a reliable estimation of the relevant incubation period, R0, Rt and death risk. Another key epidemiological parameter-asymptomatic ratio that provides strength and range for social alienation strategies of COVID-19, which is widely defined as the proportion of asymptomatic infections among all disease infections. In fact, the ratio of asymptomatic infection is a useful indicator of the burden of disease and a better measurement of the transmissibility of the virus. So far, people have not paid enough attention to asymptomatic carriers. The asymptomatic carriers discussed in this study are recessive infections, that is, those who have never shown symptoms after onset of infection. We will discuss three aspects: detection, infectivity and proportion of healthy carriers.

Title: Challenges of managing the asymptomatic carriers of SARS-CoV-2 Content: Abstract After an outbreak in Wuhan, China, a growing number of countries are now suffering from an epidemic by SARS-CoV-2, which causes COVID-19. Undoubtedly, reports of the skyrocketing global spread of COVID-19 has shocked people globally, from Japan to the United States.Presently, the World Health Organization indicates that fatality due to COVID-19 is about 2%, inferring that many positive subjects may potentially overcome the illness with mild influenza-like symptoms and no need for hospitalization at intensive-care units. Because COVID-19 is completely new to the human immune system, many throughout the world are likely vulnerable to becoming sick after their initial exposure to SARSCoV-2. Besides hospitalized cases, many individuals are likely asymptomatic but potentially carry the virus. While our knowledge about carriers and their virus shedding is deficient, some studies modelling the viral transmission have considered the potential contribution of the asymptomatic carriers. Protocols for managing asymptomatic cases, for example for controlling them to restrict their contact with healthy people at public places or private residences, have not been established.In-house quarantine may as well be applicable to asymptomatic cases if they could be identified and diagnosed. Presumably now, the asymptomatic subjects potentially contribute to the transmission of COVID-19 without their knowledge, intention or being diagnosed as carriers. Thus, managing the asymptomatic cases, who can carry and likely transmit the virus, is a major healthcare challenge while a pandemic is looming.

Title: Clinical Characteristics of 24 Asymptomatic Infections with COVID-19 Screened among Close Contacts in Nanjing, China Content: Background: Previous studies have showed clinical characteristics of patients with the 2019 novel coronavirus disease (COVID-19) and the evidence of person-to-person transmission. Limited data are available for asymptomatic infections. This study aims to present the clinical characteristics of 24 cases with asymptomatic infection screened from close contacts and to show the transmission potential of asymptomatic COVID-19 virus carriers. Methods: Epidemiological investigations were conducted among all close contacts of COVID-19 patients (or suspected patients) in Nanjing, Jiangsu Province, China, from Jan 28 to Feb 9, 2020, both in clinic and in community. Asymptomatic carriers were laboratory-confirmed positive for the COVID-19 virus by testing the nucleic acid of the pharyngeal swab samples. Their clinical records, laboratory assessments, and chest CT scans were reviewed. Findings: None of the 24 asymptomatic cases presented any obvious symptoms before nucleic acid screening. Five cases (20.8%) developed symptoms (fever, cough, fatigue and etc.) during hospitalization. Twelve (50.0%) cases showed typical CT images of ground-glass chest and five (20.8%) presented stripe shadowing in the lungs. The remaining seven (29.2%) cases showed normal CT image and had no symptoms during hospitalization. These seven cases were younger (median age: 14.0 years; P = 0.012) than the rest. None of the 24 cases developed severe COVID-19 pneumonia or died. The median communicable period, defined as the interval from the first day of positive nucleic acid tests to the first day of continuous negative tests, was 9.5 days (up to 21 days among the 24 asymptomatic cases). Through epidemiological investigation, we observed a typical asymptomatic transmission to the cohabiting family members, which even caused severe COVID-19 pneumonia. Interpretation: The asymptomatic carriers identified from close contacts were prone to be mildly ill during hospitalization. However, the communicable period could be up to three weeks and the communicated patients could develop severe illness. These results highlighted the importance of close contact tracing and longitudinally surveillance via virus nucleic acid tests. Further isolation recommendation and continuous nucleic acid tests may also be recommended to the patients discharged.

Title: Characteristics of asymptomatic patients with SARS-CoV-2 infection in Jinan, China Content: Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) is continuously and rapidly circulating at present. Asymptomatic patients have been proven to be contagious and thus pose a significant infection control challenge. Here we describe the characteristics of asymptomatic patients with SARS-CoV-2 infection in Jinan, Shandong province, China. A total of 47 patients with confirmed COVID-19 were recruited. Among them, 11 patients were categorized as asymptomatic cases. We found that the asymptomatic patients in Jinan were relatively young and were mainly clustered cases. The laboratory indicators and lung lesion on chest CT were mild. No special factors were found accounting for the presence or absence of symptoms. The presence of asymptomatic patients increased the difficulty of screening. It is necessary to strengthen the identification of such patients in the future.

Title: Comparison of transmissibility of coronavirus between symptomatic and asymptomatic patients: Reanalysis of the Ningbo Covid-19 data Content: We investigate the transmissibility of coronavirus for symptomatic and asymptomatic patients using the Ningbo Covid-19 data1. Through more in-depth and comprehensive statistical analysis, we conclude that there is no difference in the transmission rates of coronavirus between the symptomatic and asymptomatic patients, which is consistent with the original findings in Chen et al.1

Title: Identification of RT-PCR-Negative Asymptomatic COVID-19 Patients via Serological Testing Content: Asymptomatic individuals with coronavirus disease (COVID-19) have been identified via nucleic acid testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, the epidemiologic characteristics and viral shedding pattern of asymptomatic patients remain largely unknown. In this study, serological testing was applied when identifying nine asymptomatic cases of COVID-19 who showed persistent negative RT-PCR test results for SARS-CoV-2 nucleic acid and no symptoms of COVID-19. Two asymptomatic cases were presumed to be index patients who had cleared the virus when their close contacts developed symptoms of COVID-19. Three of the asymptomatic cases were local individuals who spontaneously recovered before their presumed index patients developed symptoms of COVID-19. This report presents the epidemiologic and clinical characteristics of asymptomatic individuals with SARS-CoV-2 infection that were undetected on RT-PCR tests in previous epidemiologic investigations probably due to the transient viral shedding duration.

Title: Characteristics of asymptomatic patients with SARS-CoV-2 infection in Jinan, China Content: Abstract Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) is continuously and rapidly circulating at present. Asymptomatic patients have been proven to be contagious and thus pose a significant infection control challenge. Here we describe the characteristics of asymptomatic patients with SARS-CoV-2 infection in Jinan, Shandong province, China. A total of 47 patients with confirmed COVID-19 were recruited. Among them, 11 patients were categorized as asymptomatic cases. We found that the asymptomatic patients in Jinan were relatively young and were mainly clustered cases. The laboratory indicators and lung lesion on chest CT were mild. No special factors were found accounting for the presence or absence of symptoms. The presence of asymptomatic patients increased the difficulty of screening. It is necessary to strengthen the identification of such patients in the future.

Title: The relative transmissibility of asymptomatic COVID-19 infections among close contacts Content: Asymptomatic transmission of the coronavirus disease 2019 is an important topic. A recent study in China showed that transmissibility of the asymptomatic cases is comparable to that of symptomatic cases. Here, we discuss that the conclusion may depend on how we interpret the data. To the best of our knowledge, this is the first time the relative transmissibility of asymptomatic COVID-19 infections is quantified.

Title: Estimating Hidden Asymptomatics, Herd Immunity Threshold and Lockdown Effects using a COVID-19 Specific Model Content: A quantitative COVID-19 model that incorporates hidden asymptomatic patients is developed, and an analytic solution in parametric form is given. The model incorporates the impact of lockdown and resulting spatial migration of population due to announcement of lockdown. A method is presented for estimating the model parameters from real-world data. It is shown that increase of infections slows down and herd immunity is achieved when symptomatic patients are 4-6\% of the population for the European countries we studied, when the total infected fraction is between 50-56 \%. Finally, a method for estimating the number of asymptomatic patients, who have been the key hidden link in the spread of the infections, is presented.

Title: Otolaryngology Providers Must Be Alert for Patients with Mild and Asymptomatic COVID-19 Content: More than half of COVID-19 patients are afebrile early in the disease course, yet mildly ill or asymptomatic patients can still spread SARS-CoV-2 with high efficiency. Atypically presenting patients may be seen in noninfectious disease settings such as otolaryngology, which is a specialty prone to occupational exposure. Otolaryngologists have been infected with COVID-19 at higher rates than other specialties in China and other countries. Otolaryngology providers should maintain high clinical suspicion for mild and asymptomatic COVID-19 patients. Protective strategies should be implemented including preappointment screening, triaging, restriction of nonurgent visits and surgeries, telemedicine, and appropriate personal protective equipment use.

Title: Otolaryngology Providers Must Be Alert for Patients with Mild and Asymptomatic COVID-19. Content: More than half of COVID-19 patients are afebrile early in the disease course, yet mildly ill or asymptomatic patients can still spread SARS-CoV-2 with high efficiency. Atypically presenting patients may be seen in noninfectious disease settings such as otolaryngology, which is a specialty prone to occupational exposure. Otolaryngologists have been infected with COVID-19 at higher rates than other specialties in China and other countries. Otolaryngology providers should maintain high clinical suspicion for mild and asymptomatic COVID-19 patients. Protective strategies should be implemented including preappointment screening, triaging, restriction of nonurgent visits and surgeries, telemedicine, and appropriate personal protective equipment use.

Title: Advice regarding COVID‐19 and use of immunomodulators, in patients with severe dermatological diseases Content: Coronavirus disease 2019 (COVID-19) is the disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as named by the International Committee on Taxonomy of Viruses (ICTV). There is very limited evidence base to formulate specific advice for dermatology patients on immunomodulators with regards to COVID-19. The following is based on expert opinion, taking into account known risks of influenza (a negative sense single-stranded RNA virus) and other, positive-sense single-stranded, RNA virus infections (such as SARS, MERS, and the common cold). An Australia/New Zealand consensus document is in development.

Title: Transmission and clinical characteristics of asymptomatic patients with SARS-CoV-2 infection Content: The 2019 novel coronavirus disease, SARS-CoV-2, is now spreading globally and is characterized by person-to-person transmission. However, it has recently been found that individuals infected with SARS-CoV-2 can be asymptomatic, and simultaneously a source of infection in others. The viral load detected in nasopharyngeal swabs of asymptomatic carriers is relatively high, with a great potential for transmission. More attention should be paid to the insidious spread of disease and harm contributed by asymptomatic SARS-CoV-2 carriers. To provide a theoretical basis for the accurate and early clinical identification of asymptomatic patients, this review objectively summarizes the epidemic status, transmission characteristics and clinical features of asymptomatic patients with SARS-CoV-2 infection.

Title: A study on infectivity of asymptomatic SARS-CoV-2 carriers. Content: BACKGROUND An ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread around the world. It is debatable whether asymptomatic COVID-19 virus carriers are contagious. We report here a case of the asymptomatic patient and present clinical characteristics of 455 contacts, which aims to study the infectivity of asymptomatic carriers. MATERIAL AND METHODS 455 contacts who were exposed to the asymptomatic COVID-19 virus carrier became the subjects of our research. They were divided into three groups: 35 patients, 196 family members and 224 hospital staffs. We extracted their epidemiological information, clinical records, auxiliary examination results and therapeutic schedules. RESULTS The median contact time for patients was four days and that for family members was five days. Cardiovascular disease accounted for 25% among original diseases of patients. Apart from hospital staffs, both patients and family members were isolated medically. During the quarantine, seven patients plus one family member appeared new respiratory symptoms, where fever was the most common one. The blood counts in most contacts were within a normal range. All CT images showed no sign of COVID-19 infection. No severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections was detected in 455 contacts by nucleic acid test. CONCLUSION In summary, all the 455 contacts were excluded from SARS-CoV-2 infection and we conclude that the infectivity of some asymptomatic SARS-CoV-2 carriers might be weak.

Title: Emergence of a novel human coronavirus threatening human health Content: In late December 2019, a cluster of patients with ‘atypical pneumonia’ of unknown etiology was reported in Wuhan, China. A novel human coronavirus, now provisionally called ‘SARS-CoV-2’, was identified as the cause of this disease, now named ‘COVID-19’.

Title: A study on infectivity of asymptomatic SARS-CoV-2 carriers Content: BACKGROUND: An ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread around the world. It is debatable whether asymptomatic COVID-19 virus carriers are contagious. We report here a case of the asymptomatic patient and present clinical characteristics of 455 contacts, which aims to study the infectivity of asymptomatic carriers. MATERIAL AND METHODS: 455 contacts who were exposed to the asymptomatic COVID-19 virus carrier became the subjects of our research. They were divided into three groups: 35 patients, 196 family members and 224 hospital staffs. We extracted their epidemiological information, clinical records, auxiliary examination results and therapeutic schedules. RESULTS: The median contact time for patients was four days and that for family members was five days. Cardiovascular disease accounted for 25% among original diseases of patients. Apart from hospital staffs, both patients and family members were isolated medically. During the quarantine, seven patients plus one family member appeared new respiratory symptoms, where fever was the most common one. The blood counts in most contacts were within a normal range. All CT images showed no sign of COVID-19 infection. No severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections was detected in 455 contacts by nucleic acid test. CONCLUSION: In summary, all the 455 contacts were excluded from SARS-CoV-2 infection and we conclude that the infectivity of some asymptomatic SARS-CoV-2 carriers might be weak.

Title: Severe inflammation in children - cause for awareness during the current pandemic/ Hyperinflammation hos barn kan ha samband med covid-19 Content: Clinical manifestations of COVID-19 in children are generally mild and many are asymptomatic However, recent international reports have described clusters of children presenting with an unusual syndrome of high, persistent fever, severe inflammation and single- or multiorgan dysfunction, with a suspected association to COVID-19 pandemic It is recommended that clinicians are aware of this rare syndrome and that suspected cases are treated in a multidisciplinary setting

Title: [Severe inflammation in children - cause for awareness during the current pandemic] Content: Clinical manifestations of COVID-19 in children are generally mild and many are asymptomatic However, recent international reports have described clusters of children presenting with an unusual syndrome of high, persistent fever, severe inflammation and single- or multiorgan dysfunction, with a suspected association to COVID-19 pandemic It is recommended that clinicians are aware of this rare syndrome and that suspected cases are treated in a multidisciplinary setting

Title: Why the immune system fails to mount an adaptive immune response to a Covid -19 infection. Content: The Covid-19 pandemic has already affected many thousands of people and has become the greatest health challenge worldwide [1]. The range of clinical presentations varies from asymptomatic and mild clinical symptoms to acute respiratory-distress syndrome (ARDS) and death. Due to the unknown number of asymptomatic viral-shedding and pauci-symptomatic people in the community, the total number of infections is uncertain. As yet, effective treatment is unavailable. However, the results of preliminary studies and clinical trials are improving our understanding of the pathogenesis and treatment of Covid-19. Herein, we share our personal opinions on the immunopathogenesis of this infection.

Title: An unusual case of coronavirus disease 2019: Delayed chest CT evidence Content: Asymptomatic patients and infected patients with normal chest CT imaging are considered carriers of SARS-CoV-2. Before a diagnosis of coronavirus disease 2019 (COVID-19) is made, these patients with negative chest CT findings may be ignored, causing the possibility of virus transmission. For patients with suspected infections, reliable epidemiological information and clinical symptoms, clinical management is necessary even when the chest CT is negative.

Title: Diagnóstico De Neumonía Covid 19 En Pacientes Asintomáticos Tras La Realización De Un Pet-tc Oncológico Content: INTRODUCTION: On January 30, 2020, the World Health Organization (WHO) declared an international emergency due to the pandemic caused by a new coronavirus. There are some oncological indications that have special priority and studies are still being carried out despite the current situation. In these studies we have found suspicious findings of COVID-19 pneumonia in asymptomatic patients. The objective of this work is to assess the incidence of these findings, describe their characteristics and the evolution of suspected patients. MATERIAL AND METHODS: Oncological PET studies carried out in asymptomatic patients between March 18 and April 8, 2020 have been reviewed. Patients who presented findings suggestive of corresponding to an pulmonary infectious process were selected. Clinical findings have been reviewed to confirm or rule out SARS-CoV2 infection. RESULTS: During the specified period, a total of 129 PET-CT studies were performed. Of these, 11 (8.5%) found suspicious findings of a pulmonary infectious process. These were 8 men and 3 women aged between 30 and 79 years (mean 62.2). CONCLUSIONS: Patients with COVID 19 can present few symptoms of the disease, and in PET-CT studies both presymptomatic and almost asymptomatic patients can be detected, so nuclear medicine physicians should take special attention to the pulmonary evaluation of PET-CT studies.

Title: [Severe inflammation in children - cause for awareness during the current pandemic]. Content: Clinical manifestations of COVID-19 in children are generally mild and many are asymptomatic. However, recent international reports have described clusters of children presenting with an unusual syndrome of high, persistent fever, severe inflammation and single- or multiorgan dysfunction, with a suspected association to COVID-19 pandemic. It is recommended that clinicians are aware of this rare syndrome and that suspected cases are treated in a multidisciplinary setting.

Title: Clinical characteristics of asymptomatic and symptomatic patients with mild COVID-19 Content: OBJECTIVES: Detailed knowledge on the prevalence of asymptomatic cases of coronavirus disease 2019 (COVID-19) and the clinical characteristics of mild COVID-19 is essential for effective control of the COVID-19 pandemic. We determined the prevalence of asymptomatic cases of COVID-19 and characterized the symptoms of patients with mild COVID-19. METHODS: Study participants were recruited from a community facility designated for the isolation of patients without moderate-to-severe symptoms of COVID-19 in South Korea. The prevalence of asymptomatic patients at admission and the detailed symptoms of mild COVID-19 were evaluated through a questionnaire-based survey. Diagnosis of COVID-19 was confirmed by real-time RT-PCR. RESULTS: Of the 213 individuals with COVID-19, 41 (19.2%) were asymptomatic until admission. Among the remaining patients with mild COVID-19, the most common symptom was cough (40.1%; 69/172), followed by hyposmia (39.5%; 68/172) and sputum (39.5%; 68/172). Of the 68 individuals with hyposmia, 61 (90%) had accompanying symptoms such as hypogeusia, nasal congestion or rhinorrhoea. Fever (>37.5°C) was only observed in 20 (11.6%) individuals. CONCLUSIONS: As much as one-fifth of individuals with COVID-19 remained asymptomatic from exposure to admission. Hyposmia was quite frequent among individuals with mild COVID-19, but fever was not. Social distancing should be strongly implemented to prevent disease transmission from asymptomatic individuals or those with mild and inconspicuous symptoms.

Title: Follow up investigation of asymptomatic COVID-19 cases at diagnosis in Busan, Korea Content: Objectives: The objective of the study was to conduct a follow-up investigation of 10 asymptomatic patients at diagnosis among the 98 confirmed COVID-19 cases reported in Busan between February 21 and March 13, 2020 to determine whether asymptomatic infection and transmission during asymptomatic period are possible. Methods: The study analyzed 10 asymptomatic, confirmed COVID-19 cases to determine whether asymptomatic infection is possible. We conducted in-depth interviews with patients and guardians; interviews with primary physicians; review of medical records and drug utilization review (DUR) reports; and base station-based location tracking. Results: Among the 98, confirmed COVID-19 cases reported in Busan, the study analyzed 10 (10.2%) asymptomatic patients at diagnosis. The Results confirmed that two (2.0%) patients reported to be asymptomatic during the initial epidemiological investigation, but turned symptomatic before diagnosis as per the in-depth interview results. Four cases (4.0%) of early detection led to confirmed diagnosis during the incubation period and presentation of symptoms after diagnosis. In addition, the remaining four patients (4.0%), having no subjective symptoms nor specific findings on chest radiography and Computed Tomography, remained asymptomatic until the isolation order was lifted. With regard to whether transmission during the asymptomatic period is possible, it was found that one out of 23 household contacts of the confirmed patients was identified as an additional confirmed case after coming in close contact with an index patient during the presymptomatic period. Conclusion: Among the 98 confirmed cases, asymptomatic infection was confirmed in four cases (4.0%). In addition, there was one additional confirmed case in which the patient was a family member who came in close contact with an index patient during the incubation period, thereby confirming that transmission during the asymptomatic period is possible. The possibility of transmission during the asymptomatic period has been confirmed; therefore, it is necessary to review the measures for expanding contact tracing that is currently being applied starting one day prior to the onset of symptoms.

Title: DIAGNÓSTICO DE NEUMONÍA COVID 19 EN PACIENTES ASINTOMÁTICOS TRAS LA REALIZACIÓN DE UN PET-TC ONCOLÓGICO Content: ABSTRACT INTRODUCTION: On January 30, 2020, the World Health Organization (WHO) declared an international emergency due to the pandemic caused by a new coronavirus. There are some oncological indications that have special priority and studies are still being carried out despite the current situation. In these studies we have found suspicious findings of COVID-19 pneumonia in asymptomatic patients. The objective of this work is to assess the incidence of these findings, describe their characteristics and the evolution of suspected patients. MATERIAL AND METHODS: Oncological PET studies carried out in asymptomatic patients between March 18 and April 8, 2020 have been reviewed. Patients who presented findings suggestive of corresponding to an pulmonary infectious process were selected. Clinical findings have been reviewed to confirm or rule out SARS-CoV2 infection. RESULTS: During the specified period, a total of 129 PET-CT studies were performed. Of these, 11 (8.5%) found suspicious findings of a pulmonary infectious process. These were 8 men and 3 women aged between 30 and 79 years (mean 62.2). CONCLUSIONS: Patients with COVID 19 can present few symptoms of the disease, and in PET-CT studies both presymptomatic and almost asymptomatic patients can be detected, so nuclear medicine physicians should take special attention to the pulmonary evaluation of PET-CT studies.

Title: Follow up investigation of asymptomatic COVID-19 cases at diagnosis in Busan, Korea. Content: Objectives The objective of the study was to conduct a follow-up investigation of 10 asymptomatic patients at diagnosis among the 98 confirmed COVID-19 cases reported in Busan between February 21 and March 13, 2020 to determine whether asymptomatic infection and transmission during asymptomatic period are possible. Methods The study analyzed 10 asymptomatic, confirmed COVID-19 cases to determine whether asymptomatic infection is possible. We conducted in-depth interviews with patients and guardians; interviews with primary physicians; review of medical records and drug utilization review (DUR) reports; and base station-based location tracking. Results Among the 98, confirmed COVID-19 cases reported in Busan, the study analyzed 10 (10.2%) asymptomatic patients at diagnosis. The Results confirmed that two (2.0%) patients reported to be asymptomatic during the initial epidemiological investigation, but turned symptomatic before diagnosis as per the in-depth interview results. Four cases (4.0%) of early detection led to confirmed diagnosis during the incubation period and presentation of symptoms after diagnosis. In addition, the remaining four patients (4.0%), having no subjective symptoms nor specific findings on chest radiography and Computed Tomography, remained asymptomatic until the isolation order was lifted. With regard to whether transmission during the asymptomatic period is possible, it was found that one out of 23 household contacts of the confirmed patients was identified as an additional confirmed case after coming in close contact with an index patient during the presymptomatic period. Conclusion Among the 98 confirmed cases, asymptomatic infection was confirmed in four cases (4.0%). In addition, there was one additional confirmed case in which the patient was a family member who came in close contact with an index patient during the incubation period, thereby confirming that transmission during the asymptomatic period is possible. The possibility of transmission during the asymptomatic period has been confirmed; therefore, it is necessary to review the measures for expanding contact tracing that is currently being applied starting one day prior to the onset of symptoms.

Title: The proportion of COVID-19 cases that are asymptomatic in South Korea: Comment on Nishiura et al Content: The Korean Centers for Disease Control & Prevention reports the asymptomatic case proportion for COVID-19 is 33.3%. The asymptomatic case proportion in South Korea closely approximates the rate of 30.8% reported by Nishiura et al. (2020) among Japanese nationals returning from abroad.

Title: COVID-19 – What does a paediatrician need to know? Content: COVID-19 is a coronavirus responsible for a global pandemic that started in China in December 2019 and has quickly spread to almost all countries. Approximately 2% of cases are diagnosed in children. There is increasing evidence for transmission by asymptomatic or presymptomatic adults and children. The clinical features do not differ from those of other respiratory viral infections, although rare cases manifest an unusual rash involving the digits. Disease is generally mild in children but deaths have been reported. Risk groups for severe disease in children are yet to be delineated. All treatments remain experimental.

Title: Anosmia and Ageusia: Common Findings in COVID-19 Patients Content: In a not negligible number of patients affected by COVID-19 (coronavirus disease 2019), especially if paucisymptomatic, anosmia and ageusia can represent the first or only symptomatology present. Laryngoscope, 130:1787-1787, 2020.

Title: Testing Asymptomatic Emergency Department Patients for Coronavirus of 2019 (COVID‐19) in a Low Prevalence Region Content: The first cases of Coronavirus of 2019 (COVID‐19) were reported in Wuhan, China in December 2019(1). The literature demonstrates geographical variation with regards to estimates of infection incidence, suggesting that COVID‐19 has been underdiagnosed in certain regions(2,3). The rate of asymptomatic infection has been estimated to be as high as 30.8%, which may help explain variation in incidence, particularly in regions with differing screening practices (3). Transmission of COVID‐19 by asymptomatic carriers has been reported in multiple family units, indicating that this mode of infection is important in understanding disease epidemiology and population risk(4,5).

Title: COVID-19 Transmission Within a Family Cluster by Presymptomatic Carriers in China Content: We report a family cluster of coronavirus disease 2019 (COVID-19) caused by a presymptomatic case. There were 9 family members, including 8 laboratory-confirmed with COVID-19, and a 6-year-old child had no evidence of infection. Among the 8 patients, 1 adult and a 13-month-old infant were asymptomatic, and 1 adult was diagnosed as having severe pneumonia.

Title: Prevalence of Asymptomatic SARS-CoV-2 Infection: A Narrative Review Content: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly throughout the world since the first cases of coronavirus disease 2019 (COVID-19) were observed in December 2019 in Wuhan, China. It has been suspected that infected persons who remain asymptomatic play a significant role in the ongoing pandemic, but their relative number and effect have been uncertain. The authors sought to review and synthesize the available evidence on asymptomatic SARS-CoV-2 infection. Asymptomatic persons seem to account for approximately 40% to 45% of SARS-CoV-2 infections, and they can transmit the virus to others for an extended period, perhaps longer than 14 days. Asymptomatic infection may be associated with subclinical lung abnormalities, as detected by computed tomography. Because of the high risk for silent spread by asymptomatic persons, it is imperative that testing programs include those without symptoms. To supplement conventional diagnostic testing, which is constrained by capacity, cost, and its one-off nature, innovative tactics for public health surveillance, such as crowdsourcing digital wearable data and monitoring sewage sludge, might be helpful.

Title: SARS-CoV-2 and COVID-19: The most important research questions Content: Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an ongoing global health emergency. Here we highlight nine most important research questions concerning virus transmission, asymptomatic and presymptomatic virus shedding, diagnosis, treatment, vaccine development, origin of virus and viral pathogenesis.

Title: Early viral clearance and antibody kinetics of COVID-19 among asymptomatic carriers Content: Background Asymptomatic carriers contribute to the spread of Coronavirus Disease 2019 (COVID-19), but their clinical characteristics, viral kinetics, and antibody responses remain unclear. Methods A total of 56 COVID-19 patients without symptoms at admission and 19 age-matched symptomatic patients were enrolled. RNA of SARS-CoV-2 was tested using transcriptase quantitative PCR, and the total antibodies (Ab), IgG, IgA and IgM against the SARS-CoV-2 were tested using Chemiluminescence Microparticle Immuno Assay. Results Among 56 patients without symptoms at admission, 33 cases displayed symptoms and 23 remained asymptomatic throughout the follow-up period. 43.8% of the asymptomatic carriers were children and none of the asymptomatic cases had recognizable changes in C-reactive protein or interleukin-6, except one 64-year-old patient. The initial threshold cycle value of nasopharyngeal SARS-CoV-2 in asymptomatic carriers was similar to that in pre-symptomatic and symptomatic patients, but the communicable period of asymptomatic carriers (9.63 days) was shorter than pre-symptomatic patients (13.6 days). There was no obvious differences of the seropositive conversion rate of total Ab, IgG, and IgA among the three groups, though the rates of IgM varied largely. The average peak IgG and IgM COI of asymptomatic cases was 3.5 and 0.8, respectively, which is also lower than those in symptomatic patients with peaked IgG and IgM COI of 4.5 and 2.4 (p <0.05). Conclusion Young COVID-19 patients seem to be asymptomatic cases with early clearance of SARS-CoV-2 and low levels of IgM generation but high total Ab, IgG and IgA. Our findings provide empirical information for viral clearance and antibody kinetics of asymptomatic COVID-19 patients.

Title: Characteristics of a family cluster of Severe Acute Respiratory Syndrome Coronavirus 2 in Henan, China Content: • The worldwide outbreak of SARS-CoV-2 called for more close investigations of the family transmission routes of infectious diseases. • We hypothesize that the likelihood to develop COVID-19 is probably associated with the duration of being exposed to SARS-CoV-2. • In a family cluster, asymptomatic infection carriers can be persons of all ages, from nine to sixty years old.

Title: Aktuální problematika COVID-19 z pohledu imunologa./ COVID-19 from the perspective of an immunologist Content: COVID-19 is an infectious disease caused by a coronavirus SARS-CoV-2. COVID-19 has a number of similarities to SARS and MERS diseases. Its highly contagious nature is particularly due to the rapid spread of the disease through asymptomatic individuals; however, the worlds most contagious infectious disease is still considered measles. Scientific data have revealed the interactions between COVID-19 and the immune system. These findings may contribute to the development of novel preventive and therapeutic approaches. Just as coronavirus itself the reports about the disease have massively spread through media and public contributing to overall public fear and stress. This promotion of non-scientific evidence and misinformation through social media might have also a devastating impact on the individuals immune system. Data regarding the mortality rates of COVID-19 have achieved unprecedented media and public engagements, however, the true facts about the disease prevention, immunomodulation and novel treatments are often left unsaid. We present the most recent facts about COVID-19 disease and its interactions with the immune system.

Title: COVID-19 from the perspective of an immunologist. Content: COVID-19 is an infectious disease caused by a coronavirus SARS-CoV-2. COVID-19 has a number of similarities to SARS and MERS diseases. Its highly contagious nature is particularly due to the rapid spread of the disease through asymptomatic individuals; however, the worlds most contagious infectious disease is still considered measles. Scientific data have revealed the interactions between COVID-19 and the immune system. These findings may contribute to the development of novel preventive and therapeutic approaches. Just as coronavirus itself the reports about the disease have massively spread through media and public contributing to overall public fear and stress. This promotion of non-scientific evidence and misinformation through social media might have also a devastating impact on the individuals immune system. Data regarding the mortality rates of COVID-19 have achieved unprecedented media and public engagements, however, the true facts about the disease prevention, immunomodulation and novel treatments are often left unsaid. We present the most recent facts about COVID-19 disease and its interactions with the immune system.

Title: The Role of Chest Computed Tomography in Asymptomatic Patients of Positive Coronavirus Disease 2019: A Case and Literature Review Content: Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an ongoing global health emergency. At present, patients are the primary source of infection. A randomly diagnosed confirmed case of COVID-19 highlights the importance of computerized tomography of thorax in diagnosing asymptomatic patients. In the early phase of COVID-19, routine screenings miss patients who are virus carriers, and tracking travel history is of paramount importance to early detection and isolation of SARS-CoV-2 cases.

Title: Vascular skin symptoms in COVID-19: a french observational study Content: Coronavirus 19 (COVID-19) was declared as a pandemic viral infection by the World Health organization on March 11th 2020. Usual clinical manifestations of COVID-19 infection include fever, fatigue, myalgia, headache, diarrhea, dry cough, dyspnea that may lead to acute respiratory distress syndrome and death (1). Skin symptoms of COVID-19 have been poorly described but may include erythematous rash, urticaria and chicken pox like lesions (2-7). Angiotensin-converting enzyme 2 (ACE2) is a cellular receptor for COVID-19.

Title: Thrombocytopenia as an initial manifestation of Covid-19; Case Series and Literature review. Content: Covid-19 has emerged as a global threat that has claimed millions of lives until now. Haematological manifestation as an initial presentation of this deadly virus is not frequently reported in the literature. We hereby report a case series of asymptomatic patients with severe thrombocytopenia which was later found to be Covid induced.

Title: Post-donation COVID-19 identification in blood donors. Content: The coronavirus disease 19 (COVID-19) outbreak, which was characterized as a pandemic on 11 March 2020 by the WHO, started in December 2019 with the emergence of pneumonia cases of unknown cause in Wuhan, Hubei, China [1]. SARS-CoV-2, the causative agent of COVID-19, are enveloped, non-segmented, single stranded positive sense RNA viruses and are classified as a sister clade to the prototype human and bat severe acute respiratory syndrome coronaviruses (SARS-CoVs) of the species Severe acute respiratory syndrome-related coronavirus [2]. So far, no respiratory virus, including SARS-CoV and the Middle East Respiratory Syndrome (MERS)-CoV, has been confirmed as transfusion-transmissible [3,4].

Title: Sudden hyposmia as a prevalent symptom of COVID-19 infection. Content: Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has recently caused a pandemic that has involved Italy as the second worldwide nation in terms of infected patients and deaths. The clinical manifestation of Covid-19 ranges from asymptomatic carrier status to severe pneumonia. Asymptomatic individuals in Covid-19 are those who are carriers of the virus but do not show clinical symptoms and are able to transmit the disease in the same degree as symptomatic carriers. In order to contain contagions is of supreme importance to identify asymptomatic patients because this subpopulation is one of the main factors contributing to the spread of this disease. We report on six Italian patients with COVID-19 who presented sudden hyposmia as the only or most prominent disease manifestation, without upper or lower respiratory tract involvement or other major features of the disease. A supra-threshold olfaction test confirmed the hyposmia in all patients. The onset of hyposmia during a Covid-19 outbreak should be considered as a warning sign of an infection that requires a diagnostic test for Covid-19

Title: The relative transmissibility of asymptomatic cases among close contacts Content: Abstract Asymptomatic transmission of the coronavirus disease 2019 is an important topic. A recent study in China showed that transmissibility of the asymptomatic cases is comparable to that of symptomatic cases. Here we showed that the conclusion may depend on how we interpret the data. To the best of our knowledge, this is the first time the relative transmissibility of asymptomatic COVID-19 cases is quantified.

Title: COVID-19 presenting with diarrhoea and hyponatraemia Content: COVID-19 is a viral disease with a high infectivity rate. The full spectrum of the disease is not yet understood. This understanding may help in limiting potential exposure. We present a young man with diarrhoea, abdominal pain and hyponatraemia who turned out to be positive for COVID-19.

Title: The need for neurologists in the care of COVID‐19 patients Content: Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resulting in severe acute respiratory syndrome in a substantial number of patients. Approximately 5% to 10% of patients need intensive care unit (ICU) admission and mechanical ventilation [1]. The primary symptoms of COVID-19 include fever, dry cough and fatigue [2]. However, a recent report from Shandong, China, disclosed that a subset of patients did not suffer from respiratory symptoms but had neurologic signs and symptoms [3]. Moreover, in a retrospective study from Wuhan, China, neurologic symptoms were observed in 36.4% of the hospitalized patients with COVID-19 infection and pertained to both the central and peripheral nervous system [4].

Title: Characterization of an asymptomatic cohort of SARS-COV-2 infected individuals outside of Wuhan, China Content: BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, resulting in the coronavirus disease COVID-19) is highly transmissible among people. Asymptomatic infections are also an important source of infection. Here, we aimed to further clarify the epidemiologic and clinical characteristics of asymptomatic SARS-CoV-2 infections. METHODS: We identified close contacts of confirmed COVID-19 cases in northeast Chongqing who were RT-PCR+ yet remained asymptomatic throughout their infections. We stratified this cohort by normal versus abnormal findings on chest CT, and compared the strata regarding comorbidities, demographics, laboratory findings, viral transmission and other factors. RESULTS: Between January and March, 2020, we identified and hospitalized 279 RT-PCR+ contacts of COVID-19 patients. Of these, 63 (23%) remained asymptomatic until discharge; 29 had abnormal and 34 had normal chest CT findings. The mean cohort age was 39.3 years, and 87.3% had no comorbidities. Mean time to diagnosis after close contact with a COVID-19 index patient was 16.0 days (range 1 to 29), and 13.4 days and 18.7 days for those with abnormal and normal CT findings, respectively (p < 0.05). Nine subjects (14.3%) transmitted the virus to others; 4 and 5 were in the abnormal and normal CT strata, respectively. The median length of nucleic acid turning negative in asymptomatic COVID-19 patients was 13 days, compared to 10.4 days in those with normal chest CT (p < 0.05). CONCLUSIONS: A portion of these asymptomatic individuals, with and without abnormal chest CT scans, were capable of transmitting the virus to others. Given the frequency and potential infectiousness of asymptomatic infections, testing of traced contacts is essential. Studies of the impact of treatment on asymptomatic RT-PCR+ individuals on disease progression and transmission should be undertaken.

Title: Implication of COVID‐19 in oral oncology practices in Brazil, Canada and the United States Content: The newly emerged Coronavirus disease 2019 (COVID‐19) is an infectious disease that has spread rapidly throughout the world. The most common signs and symptoms are fever, dry cough and shortness of breath which can progress to severe viral pneumonia and multi‐organ failure in susceptive patients (Chen et al. 2020, Wang et al. 2020). Droplet transmission and person‐person transmission appear to be the main route of transmission of COVID‐19, however asymptomatic patients are also carriers of the virus (Rothe et al. 2020).

Title: Unclear issues regarding COVID-19 Content: Scientists from all over the world have been intensively working to discover different aspects of Coronavi-rus disease 2019 (COVID-19) since the first cluster of cases was reported in China. Herein, we aimed to investigate unclear issues related to transmission and pathogenesis of disease as well as accuracy of diagnostic tests and treatment modalities. A literature search on PubMed, Ovid, and EMBASE databases was con-ducted, and articles pertinent to identified search terms were extracted. A snow-ball search strategy was followed in order to retrieve additional relevant articles. It was reported that viral spread may occur during the asymptomatic phase of infection, and viral load was suggested to be a useful marker to assess disease severity. In contrast to immune response against viral infections, cytotoxic T lymphocytes decline in SARS-CoV-2 infection, which can be partially explained by direct invasion of T lymphocytes or apoptosis activated by SARS-CoV-2. Dysregulation of the urokinase pathway, cleavage of the SARS-CoV-2 Spike protein by FXa and FIIa, and consumption coagulopathy were the proposed mechanisms of the coagulation dysfunction in COVID-19. False-negative rates of reverse transcriptase polymerase chain reaction varied between 3% and 41% across studies. The probability of the positive test was proposed to decrease with the number of days past from symptom onset. Safety issues related to infection spread limit the use of high flow nasal oxygen (HFNO) and continuous positive airway pressure (CPAP) in hypoxic patients. Further studies are required to elucidate the challenging issues, thus enhancing the management of COVID-19 patients.

Title: Viral kinetics of SARS-CoV-2 in asymptomatic carriers and presymptomatic patients Content: From a total of 71 laboratory-confirmed cases, three presymptomatic patients and 10 patients with entirely asymptomatic infections were identified. In two of the three incubation period patients, the viral titer in the presymptomatic period was very high (Ct value<20). The median number of days to first negative RT-PCR in the asymptomatic carriers was 4.5 (range 2.5-9), and all asymptomatic carriers reached a first RT-PCR Ct>35 within 14 days after diagnosis. Patients who have COVID-19 may already be infectious before there are symptoms, and 14 days of isolation after diagnosis may be sufficient in entirely asymptomatic cases.

Title: A COVID-19 Transmission within a family cluster by presymptomatic infectors in China Content: We report a COVID-19 family cluster caused by a presymptomatic case. There were 9 family members, including 8 laboratory-confirmed with COVID-19, and a 6-year-old child had no evidence of infection. Amongst the 8 patients, one adult and one 13-month-old infant were asymptomatic, one adult was diagnosed as having severe pneumonia.

Title: Severe Acute Respiratory Syndrome–associated Coronavirus Infection Content: Whether severe acute respiratory syndrome–associated coronavirus (SARS-CoV) infection can be asymptomatic is unclear. We examined the seroprevalence of SARS-CoV among 674 healthcare workers from a hospital in which a SARS outbreak had occurred. A total of 353 (52%) experienced mild self-limiting illnesses, and 321 (48%) were asymptomatic throughout the course of these observations. None of these healthcare workers had antibody to SARS CoV, indicating that subclinical or mild infection attributable to SARS CoV in adults is rare.

Title: Viral kinetics of SARS-CoV-2 in asymptomatic carriers and presymptomatic patients Content: Abstract From 71 laboratory-confirmed cases, we found three presymptomatic patients and 10 entirely asymptomatic infections. In two of the three incubation period patients, the viral titer in the presymptomatic period was very high (Ct value <20). The median days to first negative RT-PCR in the entirely asymptomatic carriers was 4.5 (range 2.5–9) days and all asymptomatic carriers reached a first Ct>35 RT-PCR within 14 days after diagnosis. Patients who have COVID-19 may already be infectious before there are symptoms, and 14 days of isolation after diagnosis may be sufficient in entirely asymptomatic cases.

Title: Clinical display, diagnostics and genetic implication of novel Coronavirus (COVID-19) epidemic. Content: COVID-19 pandemic can cause irreparable damage to the involved society. This study aimed to provide a summary of the up-to-dated clinical display, diagnostics, molecular and genetic implications for COVID-19 infected patients. In this review, 73 research articles published before 25 March 2020 were analyzed to better understand the clinical characteristics of patients and to introduce the available serological, hematology and molecular diagnostic methods. Apart from articles extracted from PubMed and Google Scholar, WHO (https://www.who.int/), NHC (National Health Commission of the People's Republic of China (http://www.nhc.gov.cn/), NICE (National Institute for Health and Clinical Excellence, https://www.nice.org.uk/), CDC (Centers for Disease Control and Prevention, https://www.cdc.gov/), and National Administration of Traditional Chinese Medicine (http://www.satcm.gov.cn/) were also accessed to search for eligible studies. Papers published between January 1, 2020, and 25 March 2020 were searched in English and the terms "2019-nCoV, Covid-19, Clinical Characteristics OR manifestation, method of detection, COVID-19 Genome and molecular test" were used. As the pandemic continues to evolve, there have been reports about the possibility of asymptomatic transmission of this newly emerged pneumonia virus. We highlighted the role of HLA haplotype in virus infection as HLA typing will provide susceptibility information for personalized prevention, diagnosis, and treatment in future studies. All the data in this article will assist researchers and clinicians to develop their clinical views regarding infected patients and to emphasize the origin of SARS-CoV-2 for diagnostics.

Title: Clinical display, diagnostics and genetic implication of novel Coronavirus (COVID-19) epidemic Content: COVID-19 pandemic can cause irreparable damage to the involved society. This study aimed to provide a summary of the up-to-dated clinical display, diagnostics, molecular and genetic implications for COVID-19 infected patients. In this review, 73 research articles published before 25 March 2020 were analyzed to better understand the clinical characteristics of patients and to introduce the available serological, hematology and molecular diagnostic methods. Apart from articles extracted from PubMed and Google Scholar, WHO (https://www.who.int/), NHC (National Health Commission of the People's Republic of China (http://www.nhc.gov.cn/), NICE (National Institute for Health and Clinical Excellence, https://www.nice.org.uk/), CDC (Centers for Disease Control and Prevention, https://www.cdc.gov/), and National Administration of Traditional Chinese Medicine (http://www.satcm.gov.cn/) were also accessed to search for eligible studies. Papers published between January 1, 2020, and 25 March 2020 were searched in English and the terms "2019-nCoV, Covid-19, Clinical Characteristics OR manifestation, method of detection, COVID-19 Genome and molecular test" were used. As the pandemic continues to evolve, there have been reports about the possibility of asymptomatic transmission of this newly emerged pneumonia virus. We highlighted the role of HLA haplotype in virus infection as HLA typing will provide susceptibility information for personalized prevention, diagnosis, and treatment in future studies. All the data in this article will assist researchers and clinicians to develop their clinical views regarding infected patients and to emphasize the origin of SARS-CoV-2 for diagnostics.

Title: COVID-19 masquerading as Chikungunya fever Content: The COVID-19 outbreak is an unprecedented global public health challenge. It has a myriad of clinical presentations including fever, cough, vomiting, and diarrhea. Here, we present a unique case of COVID-19, with an atypical presentation of arthralgias and false-positive results for the chikungunya virus. By highlighting the importance of this rare association, we want physicians to be vigilant in the time of this pandemic and to have a high suspicion for this novel disease.

Title: Intraoperative Diagnosis of Coronavirus Disease 2019 in an Asymptomatic Patient: A Case Report Content: Patients with coronavirus disease 2019 (COVID-19) with variable clinical presentations are encountered in the perioperative setting. While some have already been diagnosed and are symptomatic, others have undiagnosed, asymptomatic COVID-19. The latter group poses the greatest risk of transmission. Given limited capacities in most health care systems, diagnostic testing is mainly performed in symptomatic patients or those with relevant exposure. We report an intraoperative diagnosis of COVID-19 in an asymptomatic patient, prompted by clinical signs. To control a pandemic such as COVID-19, a high index of suspicion is pivotal when caring for asymptomatic patients in the perioperative setting.

Title: Cutaneous manifestations of hospitalized coronavirus disease 2019 patients: a report of six cases with clinicopathologic features and viral RNA in situ hybridization Content: Novel coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was declared a global pandemic on March, 2020.1 Recalcati et al. reported cutaneous manifestations in 20.4% of COVID-19 patients.2 We identified six patients (five female, one male) with COVID-19-associated cutaneous manifestations in April 2020 on the inpatient dermatology consultation service. The mean age was 51 years (range, 28-71 years).

Title: COVID-19: Specific and non-specific clinical manifestations and symptoms: The current state of knowledge Content: Coronavirus disease 2019 (COVID-19), due to the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become an epidemiological threat and a worldwide concern. SARS-CoV-2 has spread to 210 countries worldwide and more than 6,500,000 confirmed cases and 384,643 deaths have been reported, while the number of both confirmed and fatal cases is continually increasing. COVID-19 is a viral disease that can affect every age group—from infants to the elderly—resulting in a wide spectrum of various clinical manifestations. COVID-19 might present different degrees of severity—from mild or even asymptomatic carriers, even to fatal cases. The most common complications include pneumonia and acute respiratory distress syndrome. Fever, dry cough, muscle weakness, and chest pain are the most prevalent and typical symptoms of COVID-19. However, patients might also present atypical symptoms that can occur alone, which might indicate the possible SARS-CoV-2 infection. The aim of this paper is to review and summarize all of the findings regarding clinical manifestations of COVID-19 patients, which include respiratory, neurological, olfactory and gustatory, gastrointestinal, ophthalmic, dermatological, cardiac, and rheumatologic manifestations, as well as specific symptoms in pediatric patients.

Title: Risk factors for disease progression in COVID-19 patients Content: BACKGROUND: Coronavirus disease (COVID-19) is rapidly spreading worldwide. Although 10-20% of patients with COVID-19 have severe symptoms, little is known about the risk factors related to the aggravation of COVID-19 symptoms from asymptomatic or mild to severe disease states. METHODS: This retrospective study included 211 patients who were asymptomatic or with mild presentations of COVID-19. We evaluated the differences in demographic and clinical data between the cured (discharged to home) and transferred (aggravated to severe-stage COVID-19) groups. RESULTS: A multivariate logistic analysis showed that body temperature, chills, initial chest X-ray findings, and the presence of diabetes were significantly associated with predicting the progression to severe stage of COVID-19 (p < 0.05). The odds ratio of transfer in patients with COVID-19 increased by 12.7-fold for abnormal findings such as haziness or consolidation in initial chest X-ray, 6.32-fold for initial symptom of chills, and 64.1-fold for diabetes. CONCLUSIONS: Even if patients are asymptomatic or have mild symptoms, clinicians should closely observe patients with COVID-19 presenting with chills, body temperature > 37.5 °C, findings of pneumonia in chest X-ray, or diabetes.

Title: Risk factors for disease progression in COVID-19 patients Content: BACKGROUND: Coronavirus disease (COVID-19) is rapidly spreading worldwide. Although 10–20% of patients with COVID-19 have severe symptoms, little is known about the risk factors related to the aggravation of COVID-19 symptoms from asymptomatic or mild to severe disease states. METHODS: This retrospective study included 211 patients who were asymptomatic or with mild presentations of COVID-19. We evaluated the differences in demographic and clinical data between the cured (discharged to home) and transferred (aggravated to severe-stage COVID-19) groups. RESULTS: A multivariate logistic analysis showed that body temperature, chills, initial chest X-ray findings, and the presence of diabetes were significantly associated with predicting the progression to severe stage of COVID-19 (p < 0.05). The odds ratio of transfer in patients with COVID-19 increased by 12.7-fold for abnormal findings such as haziness or consolidation in initial chest X-ray, 6.32-fold for initial symptom of chills, and 64.1-fold for diabetes. CONCLUSIONS: Even if patients are asymptomatic or have mild symptoms, clinicians should closely observe patients with COVID-19 presenting with chills, body temperature > 37.5 °C, findings of pneumonia in chest X-ray, or diabetes.

Title: Clinical characteristics of COVID-19 in 104 people with SARS-CoV-2 infection on the Diamond Princess cruise ship: a retrospective analysis Content: BACKGROUND: The ongoing COVID-19 pandemic is a global threat. Identification of markers for symptom onset and disease progression is a pressing issue. We described the clinical features of people infected on board the Diamond Princess cruise ship who were diagnosed with asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or mild or severe COVID-19, on admission to the Self-Defense Forces Central Hospital (Tokyo, Japan) and at the end of observation. METHODS: This retrospective, single-centre study included participants with laboratory-detected SARS-CoV-2 infection who were admitted to the Self-Defense Forces Central Hospital from Feb 11 to Feb 25, 2020. Clinical records, laboratory data, and radiological findings were analysed. Clinical outcomes were followed up until discharge or Feb 26, 2020, whichever came first. We defined asymptomatic infection as SARS-CoV-2 infection with no history of clinical signs and symptoms, severe COVID-19 as clinical symptoms of pneumonia (dyspnoea, tachypnoea, peripheral capillary oxygen saturation <93%, and need for oxygen therapy), and mild COVID-19 as all other symptoms. Clinical features on admission were compared among patients with different disease severity, including asymptomatic infection, at the end of observation. We used univariable analysis to identify factors associated with symptomatic illness among asymptomatic people infected with SARS-CoV-2 and disease progression in patients with COVID-19. FINDINGS: Among the 104 participants included in the final analysis, the median age was 68 years (IQR 47–75) and 54 (52%) were male. On admission, 43 (41%) participants were classified as asymptomatic, 41 (39%) as having mild COVID-10, and 20 (19%) as having severe COVID-19. At the end of observation, 33 (32%) participants were confirmed as being asymptomatic, 43 (41%) as having mild COVID-19, and 28 (27%) as having severe COVID-19. Serum lactate hydrogenase concentrations were significantly higher in the ten participants who were asymptomatic on admission but developed symptomatic COVID-19 compared with the 33 participants who remained asymptomatic throughout the observation period (five [50%] vs four [12%] participants; odds ratio 7·25, 95% CI 1·43–36·70; p=0·020). Compared with patients with mild disease at the end of observation, patients with severe COVID-19 were older (median age 73 years [IQR 55–77] vs 60 years [40–71]; p=0·028) and had more frequent consolidation on chest CT (13 [46%] of 28 vs nine [21%] of 43; p=0·035) and lymphopenia (16 [57%] vs ten [23%]; p=0·0055) on admission. INTERPRETATION: Older age, consolidation on chest CT images, and lymphopenia might be risk factors for disease progression of COVID-19 and contribute to improved clinical management. FUNDING: None.

Title: Influenza and COVID-19 Co-infection: Report of 6 cases and review of the Literature. Content: COVID-19 pandemic caused infection in a season when influenza is still prevalent. Both viruses have similar transmission characteristics and common clinical manifestations. Influenza has been described to cause respiratory infection with some other respiratory pathogens. However the information of COVID-19 and influenza co-infection is limited. In this study, we reported our co-infected cases and reviewed the literature. We included all COVID-19 diagnosed patients. All patients with a presumed diagnosis of COVID-19 were routinely screened for influenza. Their thorax radiology was reviewed for COVID-19 -influenza differentiation. During the study period, 1103 patients have been diagnosed COVID-19. Among them, 6 patients (0.54%) were diagnosed co-infected with influenza. There have been 28 more co-infected patients reported. Laboratory-based, screening studies reported more patients. Thorax radiology findings were compatible with COVID-19 in 5 and with influenza in 1 one of our patients. Our cases were mild-to-moderate in severity. The reported cases in the literature included patients died (n=2) and those living ventilator dependent or under mechanical ventilation. COVID-19 and influenza co-infection is rare. Screening studies report more cases, suggesting that unless screening COVID-19 patients, the co-infection remains undiagnosed and underestimated. Increasing experience in thoracic radiology may contribute to diagnose the responsible virus(es) from the clinical illness. Influenza vaccine for larger population groups can be recommended to simplify clinicians' work. This article is protected by copyright. All rights reserved.

Title: COVID-19: A New Virus as a Potential Rapidly Spreading in the Worldwide Content: Covid-19 is a novel virus with high affinity to spread in the community In December 2019, it was first identified in Wuhan, China The symptoms are non-specific, so fever, cough, dyspnea, are prominent features Respiratory failure and mortality have also been reported The most common lung CT scan findings are bilateral ground glass opacities

Title: Clinical characteristics of COVID-19 in 104 people with SARS-CoV-2 infection on the Diamond Princess cruise ship: a retrospective analysis Content: BACKGROUND: The ongoing COVID-19 pandemic is a global threat. Identification of markers for symptom onset and disease progression is a pressing issue. We described the clinical features of people infected on board the Diamond Princess cruise ship who were diagnosed with asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or mild or severe COVID-19, on admission to the Self-Defense Forces Central Hospital (Tokyo, Japan) and at the end of observation. METHODS: This retrospective, single-centre study included participants with laboratory-detected SARS-CoV-2 infection who were admitted to the Self-Defense Forces Central Hospital from Feb 11 to Feb 25, 2020. Clinical records, laboratory data, and radiological findings were analysed. Clinical outcomes were followed up until discharge or Feb 26, 2020, whichever came first. We defined asymptomatic infection as SARS-CoV-2 infection with no history of clinical signs and symptoms, severe COVID-19 as clinical symptoms of pneumonia (dyspnoea, tachypnoea, peripheral capillary oxygen saturation <93%, and need for oxygen therapy), and mild COVID-19 as all other symptoms. Clinical features on admission were compared among patients with different disease severity, including asymptomatic infection, at the end of observation. We used univariable analysis to identify factors associated with symptomatic illness among asymptomatic people infected with SARS-CoV-2 and disease progression in patients with COVID-19. FINDINGS: Among the 104 participants included in the final analysis, the median age was 68 years (IQR 47-75) and 54 (52%) were male. On admission, 43 (41%) participants were classified as asymptomatic, 41 (39%) as having mild COVID-10, and 20 (19%) as having severe COVID-19. At the end of observation, 33 (32%) participants were confirmed as being asymptomatic, 43 (41%) as having mild COVID-19, and 28 (27%) as having severe COVID-19. Serum lactate hydrogenase concentrations were significantly higher in the ten participants who were asymptomatic on admission but developed symptomatic COVID-19 compared with the 33 participants who remained asymptomatic throughout the observation period (five [50%] vs four [12%] participants; odds ratio 7·25, 95% CI 1·43-36·70; p=0·020). Compared with patients with mild disease at the end of observation, patients with severe COVID-19 were older (median age 73 years [IQR 55-77] vs 60 years [40-71]; p=0·028) and had more frequent consolidation on chest CT (13 [46%] of 28 vs nine [21%] of 43; p=0·035) and lymphopenia (16 [57%] vs ten [23%]; p=0·0055) on admission. INTERPRETATION: Older age, consolidation on chest CT images, and lymphopenia might be risk factors for disease progression of COVID-19 and contribute to improved clinical management. FUNDING: None.

Title: Proportion of COVID-19 Cases that Are Asymptomatic in South Korea: Comment on Nishiura et al Content: • The Korean Centers for Disease Control & Prevention reports the asymptomatic case proportion for COVID-19 is 33.3%. • The asymptomatic case proportion in South Korea closely approximates the rate of 30.8% reported by Nishiura et al. (2020) among Japanese nationals returning from abroad. • The asymptomatic case proportion in South Korea is higher (56.1%) among those who re-test positive for COVID-19.

Title: [Screening and management of asymptomatic infection of 2019-novel coronavirus] Content: At present, the prevention and control of COVID-19 in China has entered a critical period. Recently, various areas outside Hubei Province have gradually begun to resume work and production, but the development of the epidemic situation is still uncertain and complex. A few days ago, researchers gradually began to pay attention to asymptomatic infection of 2019-novel coronavirus and described the disease process of asymptomatic infection and the possibility of being a source of infection. This provided a scientific basis for further optimizing and improving epidemic prevention and control measures. Paying attention to the screening and self-protection of high-risk groups and strengthening the level of detection should be helpful to the detection and management of asymptomatic infection.

Title: [Screening and management of asymptomatic infection of 2019-novel coronavirus]. Content: At present, the prevention and control of COVID-19 in China has entered a critical period. Recently, various areas outside Hubei Province have gradually begun to resume work and production, but the development of the epidemic situation is still uncertain and complex. A few days ago, researchers gradually began to pay attention to asymptomatic infection of 2019-novel coronavirus and described the disease process of asymptomatic infection and the possibility of being a source of infection. This provided a scientific basis for further optimizing and improving epidemic prevention and control measures. Paying attention to the screening and self-protection of high-risk groups and strengthening the level of detection should be helpful to the detection and management of asymptomatic infection.

Title: Asymptomatic transmission during the COVID-19 pandemic and implications for public health strategies Content: SARS-CoV-2 spread rapidly within months despite global public health strategies to curb transmission by testing symptomatic patients and encouraging social distancing. Here, we summarize rapidly emerging evidence highlighting transmission by asymptomatic and pre-symptomatic individuals. Viral load of asymptomatic carriers is comparable to symptomatic patients, viral shedding is highest before symptom onset suggesting high transmissibility before symptoms. Within universally tested subgroups, surprisingly high percentages of COVID-19 positive asymptomatic individuals were found. Asymptomatic transmission was reported in several clusters. A Wuhan study showed an alarming rate of intrahospital transmission, and several countries reported higher prevalence among healthcare workers than the general population. This raises concern that health workers could act as silent disease vectors. Therefore, current public health strategies relying solely on 'symptom onset' for infection identification need urgent reassessment. Extensive universal testing irrespective of symptoms may be considered with priority placed on groups with high frequency exposure to positive patients.

Title: The 2019 Novel Coronavirus Outbreak - A Global Threat Content: The 2019 Novel Corona virus infection (COVID 19) is an ongoing public health emergency of international significance. There are significant knowledge gaps in the epidemiology, transmission dynamics, investigation tools and management. In this article, we review the available evidence about this disease. Every decade has witnessed the evolution of a new coronavirus epidemic since the last three decades. The varying transmission patterns, namely, nosocomial transmission and spread through mildly symptomatic cases is an area of concern. There is a spectrum of clinical features from mild to severe life threatening disease with major complications like severe pneumonia, ARDS, acute cardiac injury and septic shock. Presence of bilateral ground glass opacity and consolidation on imaging in appropriate clinical background should raise a suspicion about COVID 19. Poor prognostic factors include Multilobular infiltration on chest imaging, Lymphopenia, Bacterial co-infection, Smoking history, Chronic medical conditions like Hypertension and age >60 years (MuLBSTA score). Diagnosis is confirmed with PCR based testing of appropriate respiratory samples. Management is primarily supportive, with newer antivirals (lopinavir ritonavir and Remdesivir) under investigation. Role of steroids is still inconclusive. Standard infection control and prevention techniques should be followed. Vigilant screening of suspected cases and their contacts is important. Isolation of symptomatic cases and home quarantine of asymptomatic contacts is recommended. To conclude, controlling this highly transmissible disease requires international co-ordination.

Title: The 2019 Novel Coronavirus Outbreak - A Global Threat. Content: The 2019 Novel Corona virus infection (COVID 19) is an ongoing public health emergency of international significance. There are significant knowledge gaps in the epidemiology, transmission dynamics, investigation tools and management. In this article, we review the available evidence about this disease. Every decade has witnessed the evolution of a new coronavirus epidemic since the last three decades. The varying transmission patterns, namely, nosocomial transmission and spread through mildly symptomatic cases is an area of concern. There is a spectrum of clinical features from mild to severe life threatening disease with major complications like severe pneumonia, ARDS, acute cardiac injury and septic shock. Presence of bilateral ground glass opacity and consolidation on imaging in appropriate clinical background should raise a suspicion about COVID 19. Poor prognostic factors include Multilobular infiltration on chest imaging, Lymphopenia, Bacterial co-infection, Smoking history, Chronic medical conditions like Hypertension and age >60 years (MuLBSTA score). Diagnosis is confirmed with PCR based testing of appropriate respiratory samples. Management is primarily supportive, with newer antivirals (lopinavir ritonavir and Remdesivir) under investigation. Role of steroids is still inconclusive. Standard infection control and prevention techniques should be followed. Vigilant screening of suspected cases and their contacts is important. Isolation of symptomatic cases and home quarantine of asymptomatic contacts is recommended. To conclude, controlling this highly transmissible disease requires international co-ordination.

Title: Novel Coronavirus COVID-19: Current Evidence and Evolving Strategies Content: COVID-19 is a global pandemic that has currently infected >300,000 globally. Fever and cough are the most common symptoms of the disease, and it is important to remember that the virus can even be transmitted by individuals who test positive for the disease but do not have any symptoms. Currently reported mortality rates vary because of the rapid spread of the disease and different approaches to calculating this estimate, but it is clear that the risk of death is associated with age and the presence of underlying conditions. Risk mitigation techniques (i.e., hand washing, social distancing, and self-isolation) have already been emphasized across major news outlets. It is essential that we continue these practices, as the outbreak is currently expected to last for many more months and we must be mindful of the lessons learned from past pandemics to prevent a second wave from occurring.

Title: Asymptomatic transmission during the COVID-19 pandemic and implications for public health strategies Content: SARS-CoV-2 spread rapidly within months despite global public health strategies to curb transmission by testing symptomatic patients and encouraging social distancing. Here, we summarize rapidly emerging evidence highlighting transmission by asymptomatic and pre-symptomatic individuals. Viral load of asymptomatic carriers is comparable to symptomatic patients, viral shedding is highest before symptom onset suggesting high transmissibility before symptoms. Within universally tested subgroups, surprisingly high percentages of COVID-19 positive asymptomatic individuals were found. Asymptomatic transmission was reported in several clusters. A Wuhan study showed an alarming rate of intrahospital transmission, and several countries reported higher prevalence among healthcare workers than the general population. This raises concern that health workers could act as silent disease vectors. Therefore, current public health strategies relying solely on ‘symptom onset’ for infection identification need urgent reassessment. Extensive universal testing irrespective of symptoms may be considered with priority placed on groups with high frequency exposure to positive patients.

Title: Coronavirus (COVID-19) Infection-Induced Chilblains: A Brisk Perieccrine Inflammatory Response Content: The varying cutaneous and pathological manifestations of coronavirus 2 (SARS-CoV-2 or COVID-19) may have prognostic implications. Acral ischemic findings present with a hypercoagulable state in critically ill COVID-19 patients. Pathologically confirmed varicella-like exanthem and perniosis COVID-19 cases have correlated with paucisymptomatic and asymptomatic patients in previous reports. We present the second case of biopsy-proven COVID-19 infection-induced chilblains (pernio) in a paucisymptomatic patient with a brisk perieccrine lymphocytic response. Based on an antecedent pathological study, we know coronavirus particles have been seen in the eccrine gland associated with a brisk peri-inflammatory response. The prominent perieccrine inflammation is helpful in the diagnosis of COVID-19 infections. Currently, nonischemic pathological findings correlate with a good prognosis based on the paucisymptomatic or asymptomatic nature of their disease courses. Patients presenting with suspected COVID-19 infection-induced chilblains who are paucisymptomatic or asymptomatic should be isolated and immediately tested with polymerase chain reaction (PCR) testing (as there is a delay in diagnosis based on the poor sensitivity of the current rapid test). We continue to stress the importance of early diagnosis and quarantining to prevent spread to the older and immunocompromised patients.

Title: Coronavirus (COVID-19) Infection-Induced Chilblains: A Brisk Perieccrine Inflammatory Response. Content: The varying cutaneous and pathological manifestations of coronavirus 2 (SARS-CoV-2 or COVID-19) may have prognostic implications. Acral ischemic findings present with a hypercoagulable state in critically ill COVID-19 patients. Pathologically confirmed varicella-like exanthem and perniosis COVID-19 cases have correlated with paucisymptomatic and asymptomatic patients in previous reports. We present the second case of biopsy-proven COVID-19 infection-induced chilblains (pernio) in a paucisymptomatic patient with a brisk perieccrine lymphocytic response. Based on an antecedent pathological study, we know coronavirus particles have been seen in the eccrine gland associated with a brisk peri-inflammatory response. The prominent perieccrine inflammation is helpful in the diagnosis of COVID-19 infections. Currently, nonischemic pathological findings correlate with a good prognosis based on the paucisymptomatic or asymptomatic nature of their disease courses. Patients presenting with suspected COVID-19 infection-induced chilblains who are paucisymptomatic or asymptomatic should be isolated and immediately tested with polymerase chain reaction (PCR) testing (as there is a delay in diagnosis based on the poor sensitivity of the current rapid test). We continue to stress the importance of early diagnosis and quarantining to prevent spread to the older and immunocompromised patients.

Title: SnapShot: COVID-19 Content: Coronavirus disease 2019 (COVID-19) is a novel respiratory illness caused by SARS-CoV-2. Viral entry is mediated through viral spike protein and host ACE2 enzyme interaction. Most cases are mild; severe disease often involves cytokine storm and organ failure. Therapeutics including antivirals, immunomodulators, and vaccines are in development. To view this SnapShot, open or download the PDF.

Title: High COVID‐19 virus replication rates, the creation of antigen–antibody immune complexes and indirect haemagglutination resulting in thrombosis Content: A new pathogenic virus, COVID-19, appeared in 2019, in Wuhan, China, typically causing fever, cough, diarrhea and fatigue and significant mortality (Mao, 2020). COVID-19 has also shown about 80% genetic similarity to the Severe Acute Respiratory Symptom (SARS) virus, which is already known to be derived from a bat virus (Ye, 2020). Arterial thrombosis and venous thrombosis, variously attributed to long term patient immobilizations, inflammation, autoimmune reactions or endothelial cell damage to the blood vessels, have also been reported for COVID-19 infections (Bikdeli, 2020; Kollas, 2020). However, another explanation for thrombosis (blood clots) in some patients infected with COVID-19 is discussed.