Epidemiological and clinical features of SARS-CoV-2 infection in children during the outbreak of Omicron variant in Shanghai, March 7-31, 2022.

OBJECTIVES: This study aimed 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 from March 7 to March 31, 2022. Clinical data, epidemiological exposure, and COVID-19 vaccination status were collected. Relative risks (RRs) 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, 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 (35.8%) received two doses of vaccines. The median interval between the completion of two-dose vaccination and infection was 3.5 (interquartile range [IQR]: 3, 4.5) months. Compared with no vaccination, two-dose COVID-19 vaccination reduced the risks of symptomatic infection and febrile disease by 35% (RR 0.65, 95% confidence interval [CI]: 0.53-0.79) and 33% (RR 0.64, 95% CI: 0.51-0.81) among confirmed cases. Eighty-four percent of symptomatic cases had fever (mean duration: 1.7 ± 1.0.8 days), 40.5% had cough, and 16.4% had transient leukopenia. Three hundred and seven (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 disease.

Comparison of Clinical and Epidemiological Characteristics of Asymptomatic and Symptomatic SARS-CoV-2 Infection in Children.

To understand the epidemiological and clinical features of the symptomatic and asymptomatic pediatric cases of COVID-19, we carried out a prospective study in Shanghai during the period of January 19 to April 30, 2020. A total of 49 children (mean age 11.5 ± 5.12 years) confirmed with SARS-CoV-2 infection were enrolled in the study, including 11 (22.4%) domestic cases and 38 (77.6%) imported cases. Nine (81.8%) local cases and 12 (31.6%) imported cases had a definitive epidemiological exposure. Twenty-eight (57.1%) were symptomatic and 21 (42.9%) were asymptomatic. Neither asymptomatic nor symptomatic cases progressed to severe diseases. The mean duration of viral shedding for SARS-CoV-2 in upper respiratory tract was 14.1 ± 6.4 days in asymptomatic cases and 14.8 ± 8.4 days in symptomatic cases (P > 0.05). Forty-five (91.8%) cases had viral RNA detected in stool. The mean duration of viral shedding in stool was 28.1 ± 13.3 days in asymptomatic cases and 30.8 ± 18.6 days in symptomatic participants (P > 0.05). Children < 7 years shed viral RNA in stool for a longer duration than school-aged children (P < 0.05). Forty-three (87.8%) cases had seropositivity for antibodies against SARS-CoV-2 within 1-3 weeks after confirmation with infection. In conclusion, asymptomatic SARS-CoV-2 infection may be common in children in the community during the COVID-19 pandemic wave. Asymptomatic cases shed viral RNA in a similar pattern as symptomatic cases do. It is of particular concern that asymptomatic individuals are potentially seed transmission of SARS-CoV-2 and pose a challenge to disease control.

A quickly, effectively screening process of novel corona virus disease 2019 (COVID-19) in children in Shanghai, China.

BACKGROUND: A recent cluster of pneumonia cases in China was caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We report the screening and diagnosis of corona virus disease 2019 (COVID-19) in our hospital. METHODS: Developed a procedure for the identification of children cases with COVID-19 in outpatient and emergency department of our hospital, then we observed how this process works. RESULTS: (I) There were 56 cases considered suspected cases, and 10 cases were confirmed as COVID-19. (II) Of the 10 confirmed COVID-19 cases admitted in our hospital, 5 were males and 5 were females, aged from 7 months to 11 years, the average age is 6.0±4.2 years, 6 cases were mild pneumonia, the others were upper respiratory tract infection. (III) We followed up 68 patients in isolation at home until symptoms disappeared. Non were missed in the patient's first visit. The sensitivity of this method is 100% and the specificity is 71.3%. CONCLUSIONS: Our screening process works well, and it is also necessary to establish a screening network in the hospital.