Analysis of Humoral Immune Responses in Patients With Severe Acute Respiratory Syndrome Coronavirus 2 Infection

J Infect Dis. 2021 Jan 4;223(1):56-61. doi: 10.1093/infdis/jiaa680.


Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has caused a pandemic with tens of millions of cases and hundreds of thousands of deaths. The infection causes coronavirus disease 2019 (COVID-19), a disease of the respiratory system of divergent severity. In the current study, humoral immune responses were characterized in a cohort of 143 patients with COVID-19 from the University Hospital Frankfurt am Main, Germany.

Methods: SARS-CoV-2-specific-antibodies were detected by enzyme-linked immunosorbent assay (ELISA). SARS-CoV-2 and human coronavirus NL63 neutralization activity was analyzed with pseudotyped lentiviral vectors.

Results: The severity of COVID-19 increased with age, and male patients encountered more serious symptoms than female patients. Disease severity was correlated with the amount of SARS-CoV-2-specific immunoglobulin (Ig) G and IgA and the neutralization activity of the antibodies. The amount of SARS-CoV-2-specific IgG antibodies decreased with time after polymerase chain reaction conformation of the infection, and antibodies directed against the nucleoprotein waned faster than spike protein-directed antibodies. In contrast, for the common flu coronavirus NL63, COVID-19 disease severity seemed to be correlated with low NL63-neutralizing activities, suggesting the possibility of cross-reactive protection.

Conclusion: The results describe the humoral immune responses against SARS-CoV-2 and might aid the identification of correlates of protection needed for vaccine development.

Keywords: COVID-19; SARS-CoV-2; antibody; coronavirus; neutralization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / immunology*
  • COVID-19 / immunology*
  • Cohort Studies
  • Cross Reactions
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Germany
  • HEK293 Cells
  • Humans
  • Immunity, Humoral*
  • Immunoglobulin A / immunology
  • Immunoglobulin G / immunology
  • Male
  • Middle Aged
  • Young Adult


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Immunoglobulin A
  • Immunoglobulin G