TORONTO — A person’s blood type may slightly lower their risk of contracting the novel coronavirus, according to a new Canadian study published in the Annals of Internal Medicine.
Researchers from the Institute for Clinical Evaluative Sciences in Toronto studied 225,556 people who tested their blood type from January 2007 to December 2019, and who later had a COVID-19 lab test. Their goal was to determine whether ABO and Rh blood groups could be associated with a risk for acquiring a SARS-CoV-2 infection and developing a severe COVID-19 illness.
According to the study, out of the more than 200,000 tests that were examined, 1,328 of them were diagnosed with severe COVID-19 illness or death, with higher probabilities among AB and B blood groups, as well as those who were Rh-positive.
Their findings indicate that O and Rh-negative blood groups were associated with a slightly lower risk for SARSCoV-2 infection as well as severe COVID-19 illness or death.
“Although we saw a statistically significant association between blood group and severe disease or death, it was also assumed that we had correctly identified severe illness associated with COVID-19,” the study says. “For example, our composite outcome did not include venous thromboembolism, which is a well-described complication of COVID-19. It is also of interest that the O blood group phenotype and genotype is associated with a decreased risk for venous thromboembolism, possibly because O group members have lower plasma levels.”
Scientists now wonder whether similar differences in blood type will be seen within ongoing clinical trials studying the therapeutic efficacy of SARS-CoV-2 immunotherapy or vaccination.
“At most, a small proportion of SARS-CoV-2 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,” the study says. “Whether this information can influence COVID-19 prevention or treatment strategies remains to be determined.”