Studies investigating fatal cases of COVID-19 found a profound dysfunction of Tregs in the lungs and pulmonary draining lymph nodes of autopsied patients, as indicated by lower FoxP3 expression, limited IL-10 production, and a paucity of FoxP3+ Tregs compared to surviving and non-COVID-19 controls (123, 124). This evidence concerns the gene FOXP3 and COVID-19.