Why blood type A may increase COVID-19 risk

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TORONTO, Ontario (CTV News) — SARS-CoV-2, the virus that causes COVID-19, may latch more easily onto the airway cells of those with type A blood than any other blood group, according to a new study.

The study, conducted in a laboratory setting by U.S. researchers, found that the coronavirus is particularly attracted to the blood group A antigen found on respiratory cells.

The new research also showed that the virus has “no preference” towards respiratory or red blood cells in type B and O blood groups.

The findings were published Wednesday in the scientific journal Blood Advances.

Various studies conducted over the past year have suggested that certain blood types may be more vulnerable to COVID-19. However, researchers behind this latest study say they’re the first to hint at a possible explanation for why those with type A blood are slightly more likely to contract the virus.

“Our observation is not the only mechanism responsible for what we are seeing clinically, but it could explain some of the influence of blood type on COVID-19 infection,” the team of researchers said in a press release.

According to the laboratory study, researchers focused on a protein on the surface of the SARS-CoV-2 virus known as the receptor-binding domain (RBD), which is the part of the virus that attaches to the host cells and infects a person.

The researchers looked at how this protein interacts with respiratory and red blood cells in A, B and O blood types.

The results showed that the RBD protein had a “strong preference” for binding to the molecules or antigens of blood type A that lined the respiratory tract, including the lungs.

According to the study, the RBD protein has no bias for blood group A red blood cells, or other blood groups found on respiratory or red cells.

Researchers say this does not mean that those with blood types B and O are immune to the virus, but said it does suggest that blood type A individuals are more likely to get infected.

The study’s lead author, Dr. Sean Stowell of Brigham and Women’s Hospital in Boston, said the RBD’s preference to “recognize and attach” to the blood type A antigen found in the lungs of those with type A blood may provide insight into the potential link between this group and coronavirus infection.

“It is interesting that the viral RBD only really prefers the type of blood group A antigens that are on respiratory cells, which are presumably how the virus is entering most patients and infecting them,” Stowell said in the release.

He added that his team plans to assess in future research how blood type “directly interacts” with SARS-CoV-2 to influence the virus’ ability to get into human cells and adhere to them.

Researchers noted that the findings do not “fully describe or predict” how coronaviruses affect patients of various blood types, but said the new data may aid in finding better treatments.

“Blood type is a challenge because it is inherited and not something we can change,” Stowell said in the release. “But if we can better understand how the virus interacts with blood groups in people, we may be able to find new medicines or methods of prevention.”