Are people with Type A blood group more prone to severe Covid-19? Two studies suggest it is unlikely

Covid-19 is unlikely to severely affect people belonging to blood group Type A, according to two studies. These findings stand in contrast to preliminary research, which suggested that individuals with this blood type are more susceptible to the infection.

Researchers from Columbia Presbyterian Hospital in their study investigated whether blood types have a part to play in the risk of getting infected, requiring ventilator support and death in 1,559 Covid-19 positive patients. These findings are published in a preprint version, meaning they are yet to be tested for accuracy. The other study released July 12 from Massachusetts General Hospital also evaluated the same in 7,770 patients across five hospitals between March 6 to April 16, 2020.

"We showed through a multi-institutional study that there is no reason to believe being a certain ABO blood type will lead to increased disease severity, which we defined as requiring intubation or leading to death," Dr Anahita Dua of Mass General, who led the study team, said in a statement. 

Preliminary studies have suggested that the people with Type O group are slightly safer than others. Columbia hospital's findings, however, do not support the theory, but researches from experts from Maschussets detected a slight link, albeit a weak one. Dua and her team also found that people with type B and AB are more likely to test positive.

Dua and her team studied the link between blood types and the rates of inflammation, which is linked to disease severity and death. “Inflammation is a particularly important finding because prevailing scientific thought is that Covid-19 wreaks havoc on the body through systemic inflammation,” Dua said. “We found, however, that inflammation markers remained similar in infected patients regardless of their blood type," she added.

But there are some loose ends. The risk of clotting can vary with blood groups. For instance, people with Type A group are less prone to clotting problems. And then, there is the body's immune system: certain blood groups make antibodies -- proteins that fight invaders -- that are different from the others. In other words, a person with O-type blood might have the antibodies to attack the virus coming from a person with type A.

"However, this protection mechanism would not work in all situations. A blood group O person could infect another blood group O person, for example," Jacques Le Pendu, research director at Inserm, a French medical research organization, told CNN. He, however, added that it might not do a great job protecting people.

Sakthivel Vaiyapuri, an associate professor in cardiovascular and venom pharmacology at the University of Reading in the UK, has a message: people with type O should not panic, and those with type O should not be cavalier. "There's so many underlying factors. We think of this as a respiratory virus, but it's really a whole collection of things going on that we don't understand yet," he told CNN.

Further studies will provide further insights into the evolving subject. “There are so many people getting infected now across the country that there will be an opportunity to study a much wider population than just New York City,” Dr Nicholas Tatonetti, a data scientist at Columbia University, told The New York Times.