Temporal patterns of asymptomatic SARS‐CoV‐2 infection among pediatric population in Japan: A 3‐year analysis

Abstract

AbstractTo elucidate the seroprevalence and rate of asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) in Japanese children, serological analysis was performed using serum samples collected from March 2020 to February 2023. A total of 1493 serum samples were collected during the first study period (March 2020 to February 2021). None of the serum samples was positive for SARS‐CoV‐2 antibody. In the second period (March 2021 to February 2022), seven of the 1055 patients (0.7%) experienced SARS‐CoV‐2 infection. The third period (March 2022 to February 2023) was divided into three terms: from March to June 30, 2022; from July to October 2022; and from November 2022 to February 2023. The seroprevalence gradually increased throughout this period, with rates of 6.0%, 18.6%, and 30.4% in the three terms, respectively. Pediatric cases of asymptomatic SARS‐CoV‐2 infection occurred after the surge of Omicron variants. Since none of the SARS‐CoV‐2 antibody‐positive patients had a previous history of coronavirus disease 2019, the seroprevalence rate in this study may represent the rate of asymptomatic infection.