Persistence of SARS-CoV-2-specific B and T cell responses in convalescent COVID-19 patients 6-8 months after the infection

Med. 2021 Mar 12;2(3):281-295.e4. doi: 10.1016/j.medj.2021.02.001. Epub 2021 Feb 10.


Background: Monitoring the adaptive immune responses during the natural course of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection provides useful information for the development of vaccination strategies against this virus and its emerging variants. We thus profiled the serum anti-SARS-CoV-2 antibody (Ab) levels and specific memory B and T cell responses in convalescent coronavirus disease 2019 (COVID-19) patients.

Methods: A total of 119 samples from 88 convalescent donors who experienced mild to critical disease were tested for the presence of elevated anti-spike and anti-receptor binding domain Ab levels over a period of 8 months. In addition, the levels of SARS-CoV-2 neutralizing Abs and specific memory B and T cell responses were tested in a subset of samples.

Findings: Anti-SARS-CoV-2 Abs were present in 85% of the samples collected within 4 weeks after the onset of symptoms in COVID-19 patients. Levels of specific immunoglobulin M (IgM)/IgA Abs declined after 1 month, while levels of specific IgG Abs and plasma neutralizing activities remained relatively stable up to 6 months after diagnosis. Anti-SARS-CoV-2 IgG Abs were still present, although at a significantly lower level, in 80% of the samples collected at 6-8 months after symptom onset. SARS-CoV-2-specific memory B and T cell responses developed with time and were persistent in all of the patients followed up for 6-8 months.

Conclusions: Our data suggest that protective adaptive immunity following natural infection of SARS-CoV-2 may persist for at least 6-8 months, regardless of disease severity. Development of medium- or long-term protective immunity through vaccination may thus be possible.

Funding: This project was supported by the European Union's Horizon 2020 research and innovation programme (ATAC, no. 101003650), the Italian Ministry of Health (Ricerca Finalizzata grant no. GR-2013-02358399), the Center for Innovative Medicine, and the Swedish Research Council. J.A. was supported by the SciLifeLab/KAW national COVID-19 research program project grant 2020.

Keywords: B cell; COVID-19; IgG; SARS-CoV-2; T cell; antibody; immunity; immunological memory; longevity of immune response; neutralizing antibody.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Viral
  • COVID-19*
  • Humans
  • Immunoglobulin A
  • Immunoglobulin G
  • SARS-CoV-2*
  • T-Lymphocytes


  • Antibodies, Viral
  • Immunoglobulin A
  • Immunoglobulin G