Serology characteristics of SARS-CoV-2 infection after exposure and post-symptom onset

Eur Respir J. 2020 Aug 27;56(2):2000763. doi: 10.1183/13993003.00763-2020. Print 2020 Aug.

Abstract

Background: Timely diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a prerequisite for treatment and prevention. The serology characteristics and complement diagnosis value of the antibody test to RNA test need to be demonstrated.

Method: Serial sera of 80 patients with PCR-confirmed coronavirus disease 2019 (COVID-19) were collected at the First Affiliated Hospital of Zhejiang University, Hangzhou, China. Total antibody (Ab), IgM and IgG antibodies against SARS-CoV-2 were detected, and the antibody dynamics during the infection were described.

Results: The seroconversion rates for Ab, IgM and IgG were 98.8%, 93.8% and 93.8%, respectively. The first detectible serology marker was Ab, followed by IgM and IgG, with a median seroconversion time of 15, 18 and 20 days post exposure (d.p.e.) or 9, 10 and 12 days post onset (d.p.o.), respectively. The antibody levels increased rapidly beginning at 6 d.p.o. and were accompanied by a decline in viral load. For patients in the early stage of illness (0-7 d.p.o), Ab showed the highest sensitivity (64.1%) compared with IgM and IgG (33.3% for both; p<0.001). The sensitivities of Ab, IgM and IgG increased to 100%, 96.7% and 93.3%, respectively, 2 weeks later. When the same antibody type was detected, no significant difference was observed between enzyme-linked immunosorbent assays and other forms of immunoassays.

Conclusions: A typical acute antibody response is induced during SARS-CoV-2 infection. Serology testing provides an important complement to RNA testing in the later stages of illness for pathogenic-specific diagnosis and helpful information to evaluate the adapted immunity status of patients.

MeSH terms

  • Adult
  • Aged
  • Betacoronavirus*
  • COVID-19
  • COVID-19 Testing
  • China
  • Clinical Laboratory Techniques*
  • Coronavirus Infections / blood*
  • Coronavirus Infections / complications
  • Coronavirus Infections / diagnosis*
  • Female
  • Hospitalization
  • Humans
  • Infectious Disease Incubation Period
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / blood*
  • Pneumonia, Viral / complications
  • Pneumonia, Viral / diagnosis*
  • SARS-CoV-2
  • Sensitivity and Specificity
  • Seroconversion
  • Symptom Assessment
  • Time Factors
  • Viral Load