CD4 and COVID-19: Of note, IFN‐γ production from CD8+ T cells and NK cells was not significantly different in blood of non‐severe and severe COVID‐19 patients, but IFN‐γ+ CD4+ T cells were likely to be reduced in severe, compared to non‐severe, COVID‐19 patients (G. Chen, Wu, et al., 2020; Qin et al., 2020).