CD4 and COVID-19: CD4/CD8 is also considered a prognostic risk factor for other infectious diseases such as Coronavirus disease 2019 (COVID-19) (8–10) and high levels of CD4+ T cells have been associated with an adequate seroconversion in PWH after vaccination against COVID-19, while PWH with low CD4 counts may not respond adequately even after receiving the complete vaccination schedule (11).