What makes some people more vulnerable to the coronavirus? Scientists are still wrangling with that, but new research sheds light on the role a person's blood may play. CNN cites two new studies published in the journal Blood Advances—one out of Denmark, the other Canada—that suggest people's blood type (A, B, AB, or O) could have something to do with their infection risk and severity. In the Danish study, researchers found 38% of their 7,400 or so COVID-19 patients were blood Type O, while just over 44% of them were Type A (they make up about equal portions of the population). Meanwhile, in the Canadian study, scientists found that among 95 ICU patients with the virus, 84% of those with Type A or AB blood needed ventilation, while only 61% of Type O or B patients did. Type A and AB patients also stayed in the ICU a median of 13.5 days, while O and B patients were there for nine.
Researchers aren't yet sure what explains why Type O blood seems to offer some small protection from the virus, speculating it could have something to do with clotting properties, how blood type antigens affect the production of antibodies, or how certain genes affect immune system receptors. The two studies complement research from earlier this year in the New England Journal of Medicine that found evidence that people with Type A blood had a higher risk of coronavirus infection, while Type O subjects had a lower risk. Still, scientists say more research is needed to lend weight to these recent findings, and that no one should start freaking out over their blood type. "If one is blood group A, you don't need to start panicking," Dr. Mypinder Sekhon, co-author of the Canadian study, says, per CNN. "And if you're blood group O, you're not free to go to the pubs and bars." (Read more discoveries stories.)