key: cord-0956681-pb9o5mzc authors: Wang, X.; Chang, H.; Tian, H.; Li, J.; Wei, Z.; Wang, Y.; Xia, A.; Ge, Y.; Wang, J.; Liu, G.; Cai, J.; Zhu, Q.; Zhu, Y.; Zhai, X.; Zeng, M. title: Epidemiological and clinical features of SARS-CoV-2 Infection in children during the outbreak of Omicron Variant in Shanghai, March 7-March 31, 2022 date: 2022-05-02 journal: nan DOI: 10.1101/2022.04.28.22274421 sha: d53078ab6dc24077bd1157c85d283ca14a92314d doc_id: 956681 cord_uid: pb9o5mzc 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. The COVID-19 pandemic has caused devastation to the world's population, resulting in more than . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted May 2, 2022. Symptomatic infection was significantly frequently seen in the age group <3 years than in the age group 3-5 years than in the age group <3 years (P=0.000) and 6-17 years (P=0.005). proportion of asymptomatic cases was 2-time more than that seen in the Wuhan outbreak. We reason that 180 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted May 2, 2022. We observed that school children aged 6-11 years comprised the most cases, followed by home-care . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted May 2, 2022. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted May 2, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted May 2, 2022. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted May 2, 2022. ; https://doi.org/10.1101/2022.04.28.22274421 doi: medRxiv preprint Age group, years . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted May 2, 2022. ; https://doi.org/10.1101/2022.04.28.22274421 doi: medRxiv preprint Living guidance for clinical management of COVID-19 Chinese Pediatric Novel Coronavirus Study 317 SARS-CoV-2 Infection in Children South Africa: a multicentre observational study Pfizer BioNTech) mRNA Vaccine in Preventing SARS-CoV-2 Infection Among 345 Children Aged 5-11 Years and Adolescents Aged 12-15 Years -PROTECT Cohort Effectiveness of 2019 Novel Coronavirus Infection: Clinical and Epidemiological Features Socio-economic impact of influenza in children:a 359 single-centered hospital study in Shanghai Virologic Features of Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Children Infectious Virus Shedding by SARS-CoV-2 Omicron Variant-Infected Vaccinees