Longitudinal observation of antibody responses for 14 months after SARS-CoV-2 infection

Clin Immunol. 2021 Sep:230:108814. doi: 10.1016/j.clim.2021.108814. Epub 2021 Jul 31.


Better understanding of antibody responses against SARS-CoV-2 after natural infection might provide valuable insights into the future implementation of vaccination policies. Longitudinal analysis of IgG antibody titers was carried out in 32 recovered COVID-19 patients based in the Umbria region of Italy for 14 months after Mild and Moderately-Severe infection.Two FDA-approved immunoassays against SARS-CoV-2 Nucleocapsid protein (NCP) and anti-spike-receptor binding domain (S-RBD) were used for sequential serological tests at different time points. The demographics,clinical history and symptom profile associated with the magnitude and longevity of antibody responses were also analyzed. Anti-S-RBD IgG persisted in 96.8% (31 of 32) subjects at 14 months. Patients reporting loss of smell and taste during the clinical course of the disease developed significantly higher antibody titers. Anti-NCP IgG seronegative patients(n=7) at 10 months, tested positive for anti-S-RBD IgG at 12,13 and 14 months emphasizing on a higher false-negative rate for NCP protein-based antibody assays. This study also highlights the importance of adopting specific immunoassays for routine estimation of antibody titers and the decreased rate of re-infections in recovered patients.

Keywords: Coronavirus; Covid19; Humoral immunity; SARS-CoV-2; neutralizing antibodies.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Antibodies, Viral / blood*
  • COVID-19 / blood
  • COVID-19 / immunology*
  • COVID-19 / prevention & control
  • COVID-19 / virology*
  • COVID-19 Vaccines / administration & dosage
  • COVID-19 Vaccines / immunology*
  • Comorbidity
  • Female
  • Humans
  • Immunoglobulin G / blood*
  • Immunoglobulin M / blood
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Pilot Projects
  • SARS-CoV-2 / immunology*
  • Time Factors


  • Antibodies, Viral
  • COVID-19 Vaccines
  • Immunoglobulin G
  • Immunoglobulin M