Age-Stratified Seroprevalence of SARS-CoV-2 Antibodies before and during the Vaccination Era, Japan, February 2020-March 2022. Academic Article uri icon

Overview

abstract

  • Japan has reported a relatively small number of COVID-19 cases. Because not all infected persons receive diagnostic tests for COVID-19, the reported number must be lower than the actual number of infections. We assessed SARS-CoV-2 seroprevalence by analyzing >60,000 samples collected in Japan (Tokyo Metropolitan Area and Hokkaido Prefecture) during February 2020-March 2022. The results showed that ≈3.8% of the population had become seropositive by January 2021. The seroprevalence increased with the administration of vaccinations; however, among the elderly, seroprevalence was not as high as the vaccination rate. Among children, who were not eligible for vaccination, infection was spread during the epidemic waves caused by the SARS-CoV-2 Delta and Omicron variants. Nevertheless, seroprevalence for unvaccinated children <5 years of age was as low as 10% as of March 2022. Our study underscores the low incidence of SARS-CoV-2 infection in Japan and the effects of vaccination on immunity at the population level.

publication date

  • October 5, 2022

Research

keywords

  • COVID-19
  • SARS-CoV-2

Identity

PubMed Central ID

  • PMC8522797

Scopus Document Identifier

  • 85140855360

Digital Object Identifier (DOI)

  • 10.3201/eid2811.221127

PubMed ID

  • 36198306

Additional Document Info

volume

  • 28

issue

  • 11