HLA-DRB1 and COVID-19: First of all, we examined the most frequent extended HLA haplotypes within the Sardinian population, and it readily became apparent that none of the 358 COVID-19 patients carried the extended haplotype HLA A*02:05, B*58:01, C*07:01, DRB1*03:01, which confirms the protective effect found for this extended haplotype in a previous study of 182 COVID-19 patients (12).