CD4 and COVID-19: Therefore, we analyzed T cell features by immunophenotyping in our cohort (Carissimo et al., 2020) and found that convalescent COVID-19 patients, in particular those with underlying cardiovascular risk, had significantly higher frequencies of effector CD8+ and CD4+ T cells (EM), and central memory CD8+ T cells (CD8 CM) than healthy controls (Figure 5a), while there were no notable differences across the groups for absolute numbers of circulating CD8+/CD4+ T cells.