Clinical features and effectiveness of SARS-CoV-2 vaccine in children with omicron infection in a tertiary hospital during the Omicron wave in China, December 2022–January 2023

There are limited data about Omicron infection in children in China. Here, we evaluated the infection fatality rates, clinical features and efficacy of SARS-CoV-2 vaccine in children with Omicron infection in a tertiary hospital during the first wave of SARS-CoV-2 caused by Omicron in China, December 2022-January 2023.We used the week as a statistical unit, and the positive rate of NAT was 0.03% from December 1 to December 7, the week before the Zero-COVID strategy was relaxed. Following the repeal of the Zero-COVID policy, the positive rate of NAT rose to 8.3% in the first week, peaked at 85.2% in the third week, and then steadily fell.The NAT positive rate in children peaked (90.4%) in the third week following the termination of the Zero-COVID policy.43.6% (232/532) of the 532 pediatric patients received vaccinations, with the majority (95.3%, 221/232) receiving two doses and the remainder receiving one.532 of the 641 pediatric patients who tested positive for NAT were seen in the pediatric outpatient clinic. Eventually, 51 pediatric patients were admitted to hospitals. Overall, the symptoms of infection were mild, and the rate of severe disease was low, whereas vaccination had a favorable effect on lowering the risk of severe illness in children.