Negligible impact of SARS-CoV-2 variants on CD4+ and CD8+ T cell reactivity in COVID-19 exposed donors and vaccinees

Tarke et al (BioRxiv). DOI: 10.1101/2021.02.27.433180



  • SARS-CoV-2 variants

  • SARS-CoV-2 specific T cells

  • SARS-CoV-2 T cell epitopes

Main Findings

Accumulating evidences highlight the impact of the mutations in SARS-CoV variants of concern (VOC) on antibody responses but the impact on T cell reactivity is still unknow. The study performed a combined experimental and bioinformatics approach to address how SARS-CoV-2 variants of concern impact T cell responses on Individuals who recovered from mild COVID-19 infection or mRNA vaccinees. Overall, memory CD4 or CD8 T cells from individuals that have been infected with the ancestral SARS-CoV-2 strain recognize the ancestral reference strain and the variant genome-wide sequences with similar efficiency. Similarly, T cell responses to the ancestral and variant strains are comparable in mRNA vaccinees. Furthermore, analysis of sets of defined SARS-CoV-2 CD4 and CD8 T cell epitopes suggest that the majority of CD8 T cell epitopes are unaffected by mutations found in all the different variants. The corresponding mutations are considered to have minor effects on the total T cell response, thus providing insights for the marginal impact on T cell reactivity by COVID-19 convalescent subjects and recipients of COVID-19 mRNA vaccines.


​As discussed by authors, the study used overlapping peptide pools, which might not address if the mutations might involve alterations in terms of antigen processing 


The study for the first time provides an insight to protective immunity or un-effected T cell responses to the mutations found in the SARS-CoV-2 variants of concern (VOC) in COVID-19 exposed individuals and vaccinees. 


Reviewed by Aljawharah Alrubayyi​ as part of the cross-institutional journal club of the Immunology Institute of the Icahn School of Medicine, Mount Sinai and the Kennedy Institute of Rheumatology, University of Oxford.