Although the further inclusion of the frequency of RhD negativity—a protein found on red blood cells, individuals with it are Rh-positive; those without it are Rh-negative; in addition, it is widely known to be important in blood transfusions and pregnancy due to immune compatibility, and its interaction with the infection in the model restored the association; the ridge regression analysis of the data—used to address multicollinearity—resulted in the disappearance of this relationship once again. This evidence concerns the gene RHD and infection.