Our results revealed an increase in the level of IL-35+IL-10+ producing CD138+CD1d+ Bregs (IL-35+IL-10+ Bregs) in the blood of severe patients compared to non-hospitalized patients with COVID-19 (30% increase in the frequency of IL-35+IL-10+ Bregs, P = 0.003; Fig. 2A). Here, CD1D is linked to COVID-19.