HLA-DRB1 and COVID-19: They found that HLA-DRB1*04:01 is significantly more frequent in severe COVID-19 patients compared to the asymptomatic staff group; they found thatHLA-DQA1*01:01, HLA-DQB1*05:01, and HLA-DRB1*01:01 are less frequent in the asymptomatic group compared to the background population [31].