Introduction: The pandemic of SARS-CoV-2 brings great challenge and threats to humans worldwide. Multiple variants of SARS-CoV-2 tend to be epidemic, among which Omicron is highly infectious within China. The aim of this study was to analyze the clinical characteristics of children infected with SARS-CoV-2 variant B.1.1.529 (Omicron) in the Shanghai, China.
Methods: We included 9378 pediatric patients diagnosed with Omicron and treated in the Shanghai International Convention and Exhibition Center between April 1, 2022 and May 31, 2022. We recorded and summarized the clinical characteristics, infectious conditions and biological features of the children infected with Omicron.
Results: A total of 9355 paediatric patients were treated in isolation since Makeshift became available, including 5564 males (59.48%) and 3791 females (40.52%). More than half (55.56%) of the affected children were identified at premises screening. The number of symptomatic or asymptomatic patients was 4530 (48.42%) and 4825 (51.58%), respectively. Initial signs or symptoms in asymptomatic patients included fatigue (3582, 38.29%), cough (560, 5.99%), fever (242, 2.59%) and other (146, 1.56%). Age and number of vaccinations in paediatric patients were negatively associated with the number of days from positive to negative nucleic acid test results.
Conclusion: Age and number of vaccinations were key factors influencing the conversion of nucleic acid test results in paediatric patients. Early childhood vaccination is encouraged to establish a complete immune barrier.

Keywords: Omicron variant, COVID-19, child patients, clinical characteristics