CD4 and COVID-19: In a study by Remy and coworkers (2020) on critically ill COVID-19 patients [65], a hypothesis diametrically opposed to the prevailing one was proposed, stating that the severity of COVID-19 is rather due to the collapse of the host’s protective immune system and a profound COVID-19-induced suppression of well-known cytokine-storm-related genes as well as the depletion of the effector cells of the immune system, such as CD3+/CD4+/CD8+ T and NK cells.