In a recent study from St. Michael’s Hospital in Toronto, researchers found that type O and rhesus-negative (Rh−) blood groups seem to be linked to a lower risk for severe COVID-19 infection.
The study is published in the Annals of Internal Medicine. One author is Joel G. Ray, M.D.
In the study, the team did a population-based study to examine whether ABO and Rh blood groups are linked to SARS-CoV-2 infection and severe COVID-19 illness.
They used data from 225,556 people (mean age, 54 years) with ABO blood group assessed between January 2007 and December 2019.
The researchers found that the risk for SARS-CoV-2 infection was lower for blood group O than the A, AB, and B blood groups together.
Rh− blood type was also linked to a reduced risk for SARS-CoV-2 infection, especially for those who were O-negative.
The risk for severe COVID-19 illness or death was lower in association with the type O blood group versus all others and for Rh− versus Rh-positive.
The researchers say at most, a small proportion of COVID-19 infection or related illness in the entire population could be prevented by some undetermined property conferred by O blood type and, perhaps, further enhanced by Rh− status.
Whether this information can influence COVID-19 prevention or treatment strategies remains to be determined in future work.