Since CD4 T cells are crucial key players in the immune defense against TB, the exhaustion of T cells in COVID-19 patients can not only contribute to the reactivation of latent TB but also the aggravation of an existing active TB infection during TB-COVID-19 co-morbidity (163–165) Besides, anti-inflammatory drugs such as corticosteroids administered to treat COVID-19 patients have the potential to create an immunosuppressive state which creates opportunities for different infections including reactivation of latent TB to occur (166). This evidence concerns the gene CD4 and infection.