Household transmission of SARS-CoV-2 during the Omicron wave in Shanghai, China：a case-ascertained study (preprint)

Since late 2021, the highly transmissible SARS-CoV-2 Omicron variant has driven a new surge of infections across the world. We used a case-ascertained study to determine the features of household transmission of SARS-CoV-2 Omicron variant in Shanghai, China. We collected detailed information on 323 pediatric cases and their 951 household members, all received consecutively intensive RT-PCR testing. We estimated the transmission parameters. Both secondary infection attack rates (SARI) and secondary clinical attack rates (SARC) among adult household contacts were computed, through which the transmission heterogeneities in infectivity and susceptibility were characterized and the vaccine effectiveness were estimated. The mean incubation period and serial interval of Omicron variant were estimated to be 4.6±2.1 days and 3.9±3.7 days. The overall SARI and SARC among adult household contacts were 77.11% (95% confidence interval [CI]: 73.58%-80.63%) and 67.03% (63.09%-70.98%). We found higher household susceptibility in females, while infectivity was not significantly different in primary cases by age, sex, vaccination status and clinical severity. Full vaccination and booster vaccination of inactivated vaccines were 14.8% (5.8%-22.9%) and 18.9% (9.0%-27.7%) effective against Omicron infection and 21.5% (10.4%-31.2%) and 24.3% (12.3%-34.7%) effective against symptomatic disease. Overall, we found high household transmission during the Omicron wave in Shanghai due to asymptomatic and pre-symptomatic transmission in the context of city-wide lockdown, indicating the importance of early detection and timely isolation of SARS-CoV-2 infections and quarantine of close contacts. Marginal effectiveness of inactivated vaccines against Omicron infection poses great challenge for prevention and control of the SARS-CoV-2 Omicron variant.

Household transmission of SARS-CoV-2 during the Omicron wave in Shanghai, China:a case-ascertained study (preprint)

Background Since late 2021, the highly transmissible SARS-CoV-2 Omicron variant has driven a new surge of infections across the world. We used a case-ascertained study to determine the features of household transmission of SARS-CoV-2 Omicron variant in Shanghai, China. Methods We collected detailed information on 323 pediatric cases and their 951 household members in April 2022 during the Omicron outbreak. All household members received consecutively intensive RT-PCR testing for SARS-CoV-2 and routine symptom monitoring within 14 days after exposure to a confirmed case. We described the characteristics of study participants and estimated the transmission parameters. Both secondary infection attack rates (SAR I ) and secondary clinical attack rates (SAR C ) among adult household contacts were computed, through which the transmission heterogeneities in infectivity and susceptibility were characterized and the vaccine effectiveness were estimated. Results We estimated the mean incubation period of SARS-CoV-2 Omicron variant to be 4.6 (median: 4.4, IQR: 3.1-6.0) days and the mean serial interval to be 3.9 (median:4.0, IQR: 1.4-6.5) days. The overall SAR I and SAR C among adult household contacts were 77.11% (95% confidence interval [CI]: 73.58%-80.63%) and 67.03% (63.09%-70.98%). We found higher household susceptibility in females, while infectivity was not significantly different in primary cases by age, sex, vaccination status and clinical severity. The estimated VEs of full vaccination was 14.8% (95% CI: 5.8%-22.9%) against Omicron infection and 21.5% (95% CI: 10.4%-31.2%) against symptomatic disease. The booster vaccination was 18.9% (95% CI: 9.0%-27.7%) and 24.3% (95% CI: 12.3%-34.7%) effective against infection and symptomatic disease, respectively. Conclusions We found high household transmission during the Omicron wave in Shanghai due to asymptomatic and pre-symptomatic transmission in the context of city-wide lockdown, indicating the importance of early detection and timely isolation of SARS-CoV-2 infections and quarantine of close contacts. Marginal effectiveness of inactivated vaccines against Omicron infection poses great challenge for prevention and control of the SARS-CoV-2 Omicron variant.

Epidemiological and clinical features of SARS-CoV-2 Infection in children during the outbreak of Omicron Variant in Shanghai, March 7-March 31, 2022 (preprint)

Objectives: To understand the epidemiological and clinical characteristics of pediatric SARS-CoV-2 infection during the early stage of Omicron variant outbreak in Shanghai. Study designs: This study included local COVID-19 cases<18 years in Shanghai referred to the exclusively designated hospital by the end of March 2022 since emergence of Omicron epidemic. Clinical data, epidemiological exposure and COVID-19 vaccination status were collected. Relative risks (RR) were calculated to assess the effect of vaccination on symptomatic infection and febrile disease. Results: A total of 376 pediatric cases of COVID-19 (median age:6.0±4.2 years) were referred to the designated hospital during the period of March 7-31, including 257 (68.4%) symptomatic cases and 119 (31.6%) asymptomatic cases. Of the 307 (81.6%) children ≥3 years eligible for COVID-19 vaccination, 110 (40.4%) received 2-dose vaccines and 16 (4.0%) received 1-dose vaccine. The median interval between 2-dose vaccination and infection was 3.5 (IQR: 3, 4.5) months (16 days-7 months). Two-dose COVID-19 vaccination reduced the risks of symptomatic infection and febrile disease by 35%(RR 0.65, 95% CI: 0.53-0.79) and 33% (RR 0.64, 95% CI: 0.51-0.81). Two hundred and sixteen (83.4%) symptomatic cases had fever (mean duration:1.7±1.0.8 days), 104 (40.2%) had cough, 16.4% had transient leukopenia; 307 (81.6%) had an epidemiological exposure in household (69.1%) , school (21.8%) and residential area (8.8%). Conclusion: The surge of pediatric COVID-19 cases and multiple transmission model reflect wide dissemination of Omicron variant in the community. Asymptomatic infection is common among Omicron-infected children. COVID-19 vaccination can offer some protection against symptomatic infection and febrile dise

Epidemiological and clinical features of SARS-CoV-2 Infection in children during the outbreak of Omicron Variant in Shanghai, March 7-March 31, 2022 (preprint)

Objectives: To understand the epidemiological and clinical characteristics of pediatric SARS-CoV-2 infection during the early stage of Omicron variant outbreak in Shanghai. Methods: This study included local COVID-19 cases <18 years in Shanghai referred to the exclusively designated hospital by the end of March 2022 since emergence of Omicron epidemic. Clinical data, epidemiological exposure and COVID-19 vaccination status were collected. Relative risks (RR) were calculated to assess the effect of vaccination on symptomatic infection and febrile disease. Results: A total of 376 pediatric cases of COVID-19 (median age:6.0{+/-}4.2 years) were referred to the designated hospital during the period of March 7-31, including 257 (68.4%) symptomatic cases and 119 (31.6%) asymptomatic cases. Of the 307 (81.6%) children;3 years eligible for COVID-19 vaccination, 110 (40.4%) received 2-dose vaccines and 16 (4.0%) received 1-dose vaccine. The median interval between 2-dose vaccination and infection was 3.5 (IQR: 3, 4.5) months (16 days-7 months). Two-dose COVID-19 vaccination reduced the risks of symptomatic infection and febrile disease by 35% (RR 0.65, 95% CI:0.53-0.79) and 33% (RR 0.64, 95% CI: 0.51-0.81). Two hundred and sixteen (83.4%) symptomatic cases had fever (mean duration: 1.7{+/-}1.0.8 days), 104 (40.2%) had cough, 16.4% had transient leukopenia; 307 (81.6%) had an epidemiological exposure in household (69.1%), school (21.8%) and residential area (8.8%). Conclusion: The surge of pediatric COVID-19 cases and multiple transmission model reflect wide dissemination of Omicron variant in the community. Asymptomatic infection is common among Omicron-infected children. COVID-19 vaccination can offer protection against symptomatic infection and febrile disease.

Chest CT and Clinical Features of COVID-19 Patients in the Early Stage of the Epidemic: An Observational Study from China (preprint)

Background: COVID-19 had caused more than 2.8 million deaths globally, and the epidemic will persist for an extended period of time. We analyzed clinical features of patients in the early stage of the epidemic, so as to deepen the understanding of the disease.Methods: In this retrospective study, we included 84 confirmed cases of COVID-19 during February 1, 2020 and March 31, 2020. Baseline data were used to classify patients as moderate (57%) or severe/critical based on Chinese protocol. We focused on analyzing the differences in chest computed tomography (CT) between the two groups. Results: Of the 84 cases, 50 were male and the median age was 69 years. 55 (65%) patients had comorbidities at admission, more in the severe/critical group (P=0.040). 94% patients had bilateral lesions on CT, up to 68% had lesions involving all lobes. Ground glass opacification (GGO) (96%), consolidation (44%), Linear opacities (50%) and Air bronchogram (23%) were the mainly lesions. The lesion was gradually absorbed over time, but imaging abnormalities can persist for a long time. Compared with moderate cases, the severe/critical group had more pulmonary consolidation changes (P=0.044) and significantly higher CT severity Score (CTSS) (P=0.040). Lymphocyte counts were significantly lower (P=0.011) and NLR were higher (P=0.029) in severe/critical cases. Conclusions: Chest CT showed bilateral and multiple GGO and consolidation mainly. After treatment, pulmonary lesions were gradually absorbed over time, and imaging abnormalities can be persistent for a long time. Lung consolidation, CTSS, comorbidity, lymphocyte counts, and NLR may be predictors of severe COVID-19.

Progressive worsening of the respiratory and gut microbiome in children during the first two months of COVID-19 (preprint)

Children are less susceptible to COVID-19 and manifests lower morbidity and mortality after infection, for which a multitude of mechanisms may be proposed. Whether the normal development of gut-airway microbiome is affected by COVID-19 has not been evaluated. We demonstrate that COVID-19 alters the respiratory and gut microbiome of children. Alteration of the microbiome was divergent between the respiratory tract and gut, albeit the dysbiosis was dominated by genus Pseudomonas and sustained for up to 25-58 days in different individuals. The respiratory microbiome distortion persisted in 7/8 children for at least 19-24 days after discharge from the hospital. The gut microbiota showed early dysbiosis towards later restoration in some children, but not others. Disturbed development of both gut and respiratory microbiomes, and prolonged respiratory dysbiosis in children imply possible long-term complications after clinical recovery from COVID-19, such as predisposition to an increased health risk in the post-COVID-19 era.

Progressive worsening of the respiratory and gut microbiome in children during the first two months of COVID-19 (preprint)

Background Children are less susceptible to COVID-19 and manifests lower morbidity and mortality after infection, for which a multitude of mechanisms may be proposed. Whether the normal development of gut-airway microbiome is affected by COVID-19 has not been evaluated.Results We demonstrate that COVID-19 alters the respiratory and gut microbiome of children. Alteration of the microbiome was divergent between the respiratory tract and gut, albeit the dysbiosis was dominated by genus Pseudomonas and sustained for up to 25–58 days in different individuals. The respiratory microbiome distortion persisted in 7/8 children for at least 19–24 days after discharge from the hospital. The gut microbiota showed early dysbiosis towards later restoration in some children, but not others.Conclusions Disturbed development of both gut and respiratory microbiomes, and prolonged respiratory dysbiosis in children imply possible long-term complications after clinical recovery from COVID-19, such as predisposition to an increased health risk in the post-COVID-19 era.

Olfactory and Gustatory Dysfunction as An Early Identifier of COVID-19 in Adults and Children: An International Multicenter Study (preprint)

Abstract Objective: Evaluate the prevalence and characteristics of olfactory or gustatory dysfunction in COVID-19 patients Study Design: Multicenter Case Series Setting: 5 tertiary care hospitals (3 in China, 1 in France, 1 in Germany) Subjects and Methods: 394 PCR confirmed COVID-19 positive patients were screened, and those with olfactory or gustatory dysfunction were included. Data including demographics, COVID-19 severity, patient outcome, and the incidence and degree of olfactory and/or gustatory dysfunction were collected and analyzed. The Questionnaire of Olfactory Disorders (QOD) and Visual Analogue Scale (VAS) were used to quantify olfactory and gustatory dysfunction respectively. All subjects at one hospital (Shanghai) without subjective olfactory complaints underwent objective testing. Results: Of 394 screened subjects, 161 (41%) reported olfactory and/or gustatory dysfunction and were included. Incidence of olfactory and/or gustatory disorders in Chinese (n=239), German (n=39) and French (n=116) cohorts were 32%, 69%, and 49% 138 respectively. The median age of included subjects was 39 years old, 92/161 (57%) were male, and 10/161 (6%) were children. Of included subjects, 10% had only olfactory or gustatory symptoms, and 19% had olfactory and/or gustatory complaints prior to any other COVID-19 symptom. Of subjects with objective olfactory testing, 10/90 demonstrated abnormal chemosensory function despite reporting normal subjective olfaction. 43% (44/102) of subjects with follow-up showed symptomatic improvement in olfaction or gustation. Conclusions: Olfactory and/or gustatory disorders may represent early or isolated symptoms of SARS-CoV-2 infection. They may serve as a useful additional screening criterion, particularly for the identification of patients in the early stages of infection.

A Case Series of Children With 2019 Novel Coronavirus Infection: Clinical and Epidemiological Features.

We first described the 2019 novel coronavirus infection in 10 children occurring in areas other than Wuhan. The coronavirus diseases in children are usually mild and epidemiological exposure is a key clue to recognize pediatric case. Prolonged virus shedding is observed in respiratory tract and feces at the convalescent stage.

A descriptive study of the impact of diseases control and prevention on the epidemics dynamics and clinical features of SARS-CoV-2 outbreak in Shanghai, lessons learned for metropolis epidemics prevention (preprint)

Objective: To describe and evaluate the impact of diseases control and prevention on epidemics dynamics and clinical features of SARS-CoV-2 outbreak in Shanghai. Design: A retrospective descriptive study Setting: China Participants: Epidemiology information was collected from publicly accessible database. 265 patients admitted to Shanghai Public Health Center with confirmed COVID-19 were enrolled for clinical features analysis. Main outcome measure: Prevention and control measures taken by Shanghai government, epidemiological, demographic, clinical, laboratory and radiology data were collected. Weibull distribution, Chi-square test, Fisher's exact test, t test or Mann-Whitney U test were used in statistical analysis. Results: COVID-19 transmission rate within Shanghai had reduced over 99% than previous speculated, and the exponential growth has been stopped so far. Epidemic was characterized by the first stage mainly composed of imported cases and the second stage where >50% of cases were local. The incubation period was 6.4 (95% CI 5.3 to 7.6) days and the mean onset-admission interval was 5.5 days (95% CI, 5.1 to 5.9). Median time for COVID-19 progressed to severe diseases were 8.5 days (IQR: 4.8-11.0 days). By February 11th, proportion of patients being mild, moderate, severe and critically ill were 1.9%(5/265), 89.8%(238/265), 3.8%(10/265), 4.5%(12/265), respectively; 47 people in our cohort were discharged, and 1 patient died. Conclusion: Strict controlling of the transmission rate at the early stage of an epidemic in metropolis can quickly prohibit the spread of the diseases. Controlling local clusters is the key to prevent outbreaks from imported cases. Most COVID-19 severe cases progressed within 14 days of disease onset. Multiple systemic laboratory abnormalities had been observed before significant respiratory dysfunction. Keyword: COVID-19, SARS-CoV-2, epidemics dynamics, diseases control, clinical features