Your blood type may make you more susceptible to contracting COVID, new research suggests. Who is most at risk

Can your blood type increase your chances of developing COVID?

The idea was floated at the start of the pandemic, as scientists worked to determine why some became much sicker than others.

Initial search suggested that those with type A blood may be at higher risk than those with type O – and new research published Tuesday in the review Blood seems to confirm the idea.

Those with type A blood — about a third of the U.S. population — are at 20% to 30% higher risk of infection with the new coronavirus than those with type O blood (nearly half of Americans), Dr. Sean Stowell, associate professor of pathology at Harvard Medical School and lead author of the study, says Fortune.

There’s no doubt that anyone – and possibly everyone – is at risk of contracting the virus. Indeed, the majority of Americans have had it, even if they don’t know it, according to data collected by U.S. public health officials who screen for COVID antibodies from infection — not vaccination — in those who have blood drawn at commercial labs.

What factors can increase my risk of contracting COVID?

There are several known factors that influence whether, and how badly, one is infected with COVID. They understand whether or not his immune system is working well; whether or not a person has diabetes, obesity, or other health conditions that seem to predispose them to the disease; and the amount of virus to which one is exposed.

Blood type seems to be another factor that tips the scales. All things being equal, if a type A and a type O are sitting side by side and are both coughed up by a COVID-positive person, the type A is slightly more likely to get sick, Stowell says. The same goes for the original SARS-CoV-1 coronavirus, which caused the first pandemic of the 21st century, in 2003.

Is the research still relevant? The planet is no longer in a state of pandemic, according to the World Health Organization, which said so in May.

The virus is however are still circulating around the levels observed during the summers of 2020 and 2021, according to US wastewater data, and is far from a thing of the past. It currently doesn’t cause serious disease for the most part, but evolution could push it toward the dangerous end of the spectrum, Stowell and other experts say.

The story continues

So knowing “one tiny piece of the puzzle” — how blood type affects one’s susceptibility — might become relevant again in the future, if new, potentially troublesome variants emerge, Stowell says.

This knowledge could also help scientists understand how and why other viruses, such as cholera and malaria, also tend to prefer certain blood types, he adds.

Further research needs to be conducted to understand if COVID shows a preference for B and/or AB blood types. Stowell’s team is currently studying how the virus reacts to type B. While research is ongoing, whether or not a person has such a blood type may become more relevant if they are exposed to the virus through oral route.

The hypothesis has not been tested, but “it is possible”, he says.

This story was originally featured on Fortune.com

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