Our view is that, in some cohorts that have been studied, aged donors suffering from, e.g., heart disease, cancer or neurodegenerative disorders may not control virus efficiently leading to increased HCMV IgG levels or HCMV DNAemia and concomitant increased numbers of differentiated memory T cell populations and an inverted CD4:CD8 ratio, thereby confounding some studies. Here, CD4 is linked to cancer.