CD4 and COVID-19: With regard to the adaptive immune responses against SARS-CoV-2 variants in COVID-19 convalescents [45], 93% and 97% of previously identified CD4+ and CD8+ T cell epitopes (i.e., B.1.1.7, B.1.351, P.1, and CAL.20C lineages) were not affected by mutations [45].