The study, published in the New England Journal of Medicine, compared 1,900 people undergoing treatment for severe COVID-19 and respiratory failure at seven medical centers in Italy and Spain to 1,200 healthy blood donors from the same population groups.
Researchers combed through genetic codes looking for similarities. One similarity they found among the ill patients was a DNA cluster which determines blood types. This prompted further research into which specific blood types were present in the majority of severe coronavirus cases in the sample population.
Results indicated that people with Type A blood had a 45% higher risk of infection than those with other blood types.
Similarly, researchers identified a “protective effect” in people with Type O blood, saying they were only two-thirds as likely to become infected.
The results hinge from a DNA cluster observed at a specific chromosome that scientists believe is relevant to COVID-19 infection.
However, researchers state that this study cannot accurately name a causative gene based on its presented evidence. Scientists cite time constraints and confounding variables that were not controlled for, such as underlying cardiovascular and metabolic conditions, as reasons for potential inaccuracies.
Meanwhile, Roy Silverstein, a hematologist at the Medical College of Wisconsin, told MarketWatch that the aforementioned DNA cluster can be found in other parts of the body. He says blood types may not totally predict an individual’s risk of contracting the coronavirus.
“Those who are not Type A should not interpret this study to mean that they can let their guard down,” Silverstein reportedly said. “Similarly, the data are not yet convincing enough to recommend that those with Type A need to do even more than what is recommended.”
Scientists say further research must still be conducted into these findings. They remind citizens that while this study shows correlation between blood types and severity of illness, it does not necessarily indicate causation.
“Everyone needs to pay attention to COVID-19 prevention by following well-accepted guidelines related to social distancing, face covering, hand-washing, and self-isolation and testing in the setting of possible COVID-related symptoms,” Silverstein added.