Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections

Nat Med. 2020 Aug;26(8):1200-1204. doi: 10.1038/s41591-020-0965-6. Epub 2020 Jun 18.

Abstract

The clinical features and immune responses of asymptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well described. We studied 37 asymptomatic individuals in the Wanzhou District who were diagnosed with RT-PCR-confirmed SARS-CoV-2 infections but without any relevant clinical symptoms in the preceding 14 d and during hospitalization. Asymptomatic individuals were admitted to the government-designated Wanzhou People's Hospital for centralized isolation in accordance with policy1. The median duration of viral shedding in the asymptomatic group was 19 d (interquartile range (IQR), 15-26 d). The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P = 0.028). The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6-10.7) were significantly lower (P = 0.005) relative to the symptomatic group (median S/CO, 20.5; IQR, 5.8-38.2) in the acute phase. Of asymptomatic individuals, 93.3% (28/30) and 81.1% (30/37) had reduction in IgG and neutralizing antibody levels, respectively, during the early convalescent phase, as compared to 96.8% (30/31) and 62.2% (23/37) of symptomatic patients. Forty percent of asymptomatic individuals became seronegative and 12.9% of the symptomatic group became negative for IgG in the early convalescent phase. In addition, asymptomatic individuals exhibited lower levels of 18 pro- and anti-inflammatory cytokines. These data suggest that asymptomatic individuals had a weaker immune response to SARS-CoV-2 infection. The reduction in IgG and neutralizing antibody levels in the early convalescent phase might have implications for immunity strategy and serological surveys.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Asymptomatic Infections*
  • Betacoronavirus / immunology
  • Betacoronavirus / pathogenicity
  • Child
  • China / epidemiology
  • Coronavirus Infections / blood*
  • Coronavirus Infections / epidemiology
  • Coronavirus Infections / immunology*
  • Coronavirus Infections / virology
  • Cytokines / blood
  • Cytokines / immunology
  • Female
  • Hospitalization
  • Humans
  • Immunity, Innate*
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / blood*
  • Pneumonia, Viral / epidemiology
  • Pneumonia, Viral / immunology*
  • Pneumonia, Viral / virology
  • Young Adult

Substances

  • Cytokines
  • Immunoglobulin G

Supplementary concepts

  • COVID-19
  • severe acute respiratory syndrome coronavirus 2