CD8A and viral infectious disease: The importance of cytotoxic T lymphocytes in viral infections has taken on new significance in relation to the current coronavirus disease (COVID)-19 pandemic caused by the severe acute respiratory syndrome coronavirus (SARS-COV)-2 virus, where deficiencies in the CD8 T response are associated with higher morbidity and mortality, with an increased disease recurrence, as occurs in elderly or immunocompromised patients (1, 2).