Several independent datasets suggest blood type A is over-represented and type O under24 represented among COVID-19 patients. Here, I model a scenario in which ABO transfusion incompatibility reduces the chance of a patient transmitting the virus to an incompatible recipient. Comparison of model outputs to published data on COVID-19 prevalence indicates that if this scenario holds true, ABO incompatibility may reduce virus transmissibility by 60% or more. Paradoxically, however, targeted vaccination of either high-susceptibility type A or “super spreader” type O individuals is less effective than random vaccination at blocking community spread of the virus. Instead, the key is to maintain blood type diversity amongst the remaining susceptible individuals. I stress that these results illustrate a theoretical model of ABO blood group interaction with virus transmission and require confirmation by observation.
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Modelling suggests blood group incompatibility may substantially reduce SARS-CoV-2 transmission
Several recent published studies and preprints have suggested that the prevalence of COVID39 19 disease varies by blood type, with type A being relatively susceptible and type O being less susceptible. Puzzlingly, however, there is no difference in the severity of disease, with the case fatality ratio (CFR) and the probability of progressing to intensive care appearing independent of blood type. This discrepancy between incidence and severity data has led some authors to challenge the aforementioned findings. Although not remarked on to date, in the majority of these studies type AB appears even more susceptible than type A. Thus, the relative risk of infection is AB > A > B > O, with type A and type B alleles functioning codominantly to increase risk. This is immediately reminiscent of the rules governing blood transfusion compatibility.