Fig. 3: Potential impact of SARS-CoV-2 variants on T cell responses and innate immunity.

a, Following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, CD4⁺ T cell and CD8⁺ T cell responses are generated against 30–40 epitopes across the virus genome¹¹⁰ (epitopes are shown in red and blue). b, An example of how an amino acid change within one epitope might impact epitope-specific cytotoxic T cell responses, thereby inhibiting the elimination of virus-infected cells¹¹⁵. T cell evasion of SARS-CoV-2 has been shown to be the consequence of impaired peptide binding to the major histocompatibility complex (MHC) or poor binding of the T cell receptor (TCR) to the peptide–MHC complex. c, Although the T cell response to vaccination is focused on the spike protein alone, even the multiple spike mutations in the Omicron variant of concern reduce the vaccine-induced spike-specific T cell response only by less than 30%, with considerable interindividual variability^120,191. M, membrane protein; N, nucleocapsid protein.