FOXP3 and COVID-19: Therefore, based on the gating strategy represented in Supplementary Fig. 2A, we observed that both the frequency and absolute number of circulating FOXP3+T regulatory cells were reduced in COVID-19 patients compared to healthy controls, and no difference was observed between patients that required or not mechanical ventilation (Fig. 1A,B). Stratifying the intubated patients according to their survival, despite no significant difference in the frequency of FOXP3+ T regulatory cell repertoire (Fig. 1A,C), we detected higher circulating cell numbers among the non-survivors (Fig. 1D).