Testing the association between blood type and COVID-19 infection, intubation, and death

Michael Zietz; Nicholas P. Tatonetti

Since both blood groups and risk factors vary across populations, we thought it was important to evaluate the associations we found in a multivariate context as well. Indeed, we found significant associations between risk factors and blood groups. However, the significant associations between blood group and COVID-19 status were reflected in significant reductions in deviance when adding blood group to a regression of risk factors on COVID-19 status. Moreover, the blood group regression coefficients were largely unchanged when risk factors were present or not, indicating that blood groups have an independent effect on COVID-19 status not captured by the risk factors. These results suggest that the significant associations we discovered are not explained by confounding due to these risk factors.