TNFR1, an indicator of inflammaging, was inversely associated with naïve T cells in the HRS, positively associated with odds of hospitalization or death from COVID-19 in the UKB, and mediated the associations between older age and these outcomes (10% for CD4T, 5% for CD8T, 16% for COVID-19). This evidence concerns the gene TNFRSF1A and COVID-19.