Patients experiencing GI long COVID also had persistent CMV-specific CD8+ T cells—in the absence of CMV viraemia—expressing a more pronounced cytotoxicity transcriptomic signature compared to CMV-specific CD8+ T cells from healthy SARS-CoV-2-unexposed individuals [42], implicating bystander T cell activation in long COVID, as previously noted in mild acute COVID-19 patients [43]. This evidence concerns the gene CD8A and COVID-19.