In a study carried out in China on 21 confirmed cases with COVID-19, levels of IL2, IL2 receptor (IL2R), IL6, IL10, and TNF-α were significantly higher in severe cases than in milder infections, and this was associated with a reduction of absolute numbers of total T-cells, CD4 + , and CD8 + in the majority of patients [19]. This evidence concerns the gene CD4 and COVID-19.