CD38 and COVID-19: Although we did not find a significant increase in the frequency of circulating TFH, they were more activated in patients with severe COVID-19, suggesting that these CD38+HLA-DR+ TFH had a recent antigen encounter and may be providing B cell help (38), possibly as a part of an extrafollicular response, which somehow is explained by the observed low levels of CXCR5 in B cells from patients with severe disease.