HLA-A and COVID-19: Since 70.6% (36/51) of COVID-19 convalescents (mild, 60.0% (12/20); moderate, 84.6% (11/13); and severe, 72.2% (13/18)) and 75.0% (9/12) of healthy controls enrolled in this study carried an HLA-A*24:02 allele, K562 cells were firstly engineered to express HLA-A*24:02, and the costimulatory molecule 4-1BBL (Supplementary Fig. 1a, b)18,19.