CD4 and COVID-19: A study by Puzyrenko et al. also highlighted the presence of a large component of CD8+ T cells in COVID-19 victims [37], but other comparative histopathological studies between COVID-19 and influenza showed that several features (including lymphocyte infiltrates in lungs) were similar, also in terms of CD8+ T cell tissue recruitment and CD8/CD4 ratio [38,39].