CD8A and infection: Virus-specific CD8+ T cells are shown to control replication and shedding of other mucosal viruses, including influenza, VZV, HIV, and SAR-CoV2 (35–38) and recent studies examining hetero-variant protection following natural infection with respiratory viruses have demonstrated the importance of cross-reactive CD8+ T cell populations, which can migrate between the blood and tissues (39–45).