Accordingly, we and others have described that immune cells from patients with COVID-19 show significantly higher levels of exhaustion markers such as PD-1 and Tim-3 (7, 43, 58), increased regulatory T cell (Treg) counts, CD4 lymphopenia, and impaired direct cytotoxicity (DCC) (7, 59, 60), which may consequently influence on the reactivation of CMV and EBV proviruses. This evidence concerns the gene HAVCR2 and COVID-19.