The hypothesized conferred protection against COVID-19 could also derive from local SE Asian HLA-class allotypes, possibly in linkage disequilibrium with the thalassemia mutations. Protection from and resistance to severe malaria has been described in association with HLA antigens in the African continent [54,55] and the ABO blood group system [56]. However, no HLA associations with COVID-19 infection have been noted in a recent report [57] but an association with the ABO blood group system was confirmed, with bearers of the blood group A phenotype showing an increased risk for COVID-19 infection compared to blood group O [58]. The O phenotype appears protective to malaria [56] and its worldwide distribution seems to have been shaped by the parasite’s selective genetic pressure [56]. The frequency of the O blood group in Thailand is 40.5% [59] and its relatively high prevalence along with the high HbE heterozygote frequency could further potentiate the hypothesized antiviral protective effect.