Evaluating the presence of immunological memory T cells in the peripheral blood of children who had recovered from mild COVID-19, Tian et al. demonstrated that in children aged 0 to 4 years, both CD4+ and CD8+ T cell levels exhibited a considerable rise in central memory (CD45RA- CCR7+ (TCM)) and effector memory (CD45RA- CCR7+ (TEM)) cell proportions. Here, CD4 is linked to COVID-19.