Seroprevalence kinetics of SARS-CoV-2 antibodies in pediatric patients visiting a hospital during COVID-19 pandemic in Japan

J Infect Chemother. 2024 Feb;30(2):169-171. doi: 10.1016/j.jiac.2023.09.020. Epub 2023 Sep 19.


Children infected with SARS-CoV-2 are often asymptomatic or have mild symptoms. The studies on the seroprevalence kinetics of SARS-CoV-2 antibodies in children are limited. We conducted a cross-sectional survey of the positive rate of the SARS-CoV-2 IgG in pediatric patients without suspected COVID-19 infection between January 2007 and March 2022. We defined the serum samples from the pre-pandemic and pandemic groups (1st-6th waves). Totally, 2557 samples were collected and no samples from the pre-pandemic group or the 1st-4th waves were positive for IgG. There were 4/661 and 16/373 positives at the 5th and 6th waves, respectively. At the 5th wave, the prevalence of IgG was 1.3% in children aged 1-4 years. At the 6th wave, in children <1 year of age, the prevalence was 4.0%, and 2.4%, 5.3%, 5.2% and 10% in age groups 1-4, 5-9, 10-14 and 15-18 years, respectively. In conclusions, the pre-pandemic samples were negative, and the IgG positivity increased during the later period of the pandemic.

Keywords: COVID-19 pandemic; Children; SARS-CoV-2 antibody; Seroprevalence.

MeSH terms

  • Antibodies, Viral
  • COVID-19* / epidemiology
  • Child
  • Cross-Sectional Studies
  • Hospitals
  • Humans
  • Immunoglobulin G
  • Infant
  • Japan / epidemiology
  • Pandemics
  • SARS-CoV-2
  • Seroepidemiologic Studies


  • Antibodies, Viral
  • Immunoglobulin G