Although SARS-CoV-2 mutations that abrogate binding to major histocompatibility complex have been reported,4 Tarke et al.5 recently reported an insignificant impact of SARS-CoV-2 variants on both CD4+ and CD8+ T-cell responses in COVID-19 convalescents and recipients of COVID-19 mRNA vaccines. This evidence concerns the gene CD4 and COVID-19.