They found that people with Blood Type have a higher risk of contracting the coronavirus and developing severe symptoms, while people with Blood Type of O have a lower risk.
“Our genetic data confirms that group O blood is associated with a lower risk of contracting Covid-19 than in non-O blood groups, while group A blood has been associated with a higher risk than non-One blood groups, ”the researchers wrote in their report. They found that people with Blood Type had a 45% increased risk of being infected than people with other blood types, and people with O Blood Type were only 65% more likely to be infected than people with other blood types.
The large international team first published their results on a non-peer-reviewed server preprint basis. The report was reviewed and published in the highly respected newspaper.
The researchers, led by André Franke, a professor of molecular medicine at the University of Kiel, Germany, studied more than 1,900 critically ill coronavirus patients, in Spain and Italy, and compared them to 2,300 people who weren’t sick. They did what is known as a genome-wide association study, trawling through the entire genetic map to find two variations of DNA that were more common in the sickest patients.
“We have detected a novel locus of susceptibility to a chromosome 3p21.31 gene cluster and confirmed the potential involvement of the ABO-blood group system in Covid-19,” they wrote. And two places in the genome have been linked with the risk of developing respiratory failure.
Researchers cannot say whether the blood type is a direct cause of the differences in sensitivity. It may be that the genetic changes that affect the risks also just happen to be linked with the type of blood, they said.
The two genetic variations they found could be associated with a person’s immune response. A so-called cytokine storm – an overwhelming overreaction of the immune system – is blamed for the deadliest coronavirus effect in many patients.
Dr. Roy Silverstein, a hematologist who is the chair of the department of medicine at the Wisconsin Medical College, said the link blood type is plausible.
The genes that control the blood type also affect the structures called sugars on the surface of cells, which could affect the ability of the virus to infect cells, he says. Additionally, blood type is linked with the risk of developing blood clots, and it is now clear that serious coronavirus infections are marked by unusual clotting of blood throughout the body.
But Silverstein, a former president of the American Society of Hematology, said the results mean very little for the average person. While the increased risk may seem large, out of a whole population of people it’s not good at all, he told CNN.
“The absolute difference in risk is very small,” he says. “The risk reduction may be statistically significant, but it is a small change in the actual risk. You would never tell someone who was Type O that they were at the lowest risk of infection, “he said.
What the results are most useful for would be in the design of coronavirus drugs or vaccines, the researchers say.