SARS-CoV-2 Antibody Response to Symptoms Indicative of COVID-19 in a Non-Infected Population in Japan: a Cross-Sectional Study

Jpn J Infect Dis. 2023 Jan 24;76(1):46-54. doi: 10.7883/yoken.JJID.2022.093. Epub 2022 Sep 30.


This study was aimed at investigating differences in antibody titers indicative of the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between those who had experienced symptoms of coronavirus disease 2019 (COVID-19) and those who had not. We used data from a cross-sectional survey conducted at the National Cancer Center, Japan, of 434 individuals with no previous COVID-19 infection. The participants self-reported symptoms from the start of 2020. A generalized linear model was used to compare the mean SARS-CoV-2-specific IgG nucleocapsid protein (N-IgG) titer with estimated confidence intervals according to the onset of symptoms indicative of COVID-19. We observed a tendency toward an association between higher mean N-IgG titers and occurrence of high fever within the past 8 months (P = 0.053). The mean N-IgG titer was higher in those with prior symptoms (P = 0.03) and those with over three symptoms (P < 0.01) than in those without symptoms. The mean N-IgG titer was higher in those with symptoms and those with more symptoms that might indicate COVID-19 relative to those without symptoms, suggesting that transient but contained SARS-CoV-2 infection had occurred.

Keywords: COVID-19; Japan; SARS-CoV-2; antibody; symptom.

MeSH terms

  • Antibodies, Viral
  • Antibody Formation
  • COVID-19* / diagnosis
  • Cross-Sectional Studies
  • Humans
  • Immunoglobulin G
  • Japan / epidemiology
  • SARS-CoV-2


  • Antibodies, Viral
  • Immunoglobulin G