An illustration where a person in a diving suit is swimming through a blue SARS-CoV-2 with a flashlight that shines red.
Illustration: Kieran Blakey

The Nuance

The Truth About Blood Types and the Coronavirus

Some experts say that reports linking certain blood types to lower infection risks are ‘flawed’

Elemental
Published in
7 min readJul 2, 2020

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Recently, the New England Journal of Medicine published a study that found links between Covid-19 and certain genetic and blood-type variables. While the authors emphasized the potential usefulness of their gene-related findings, which implicated clusters of genes on a specific chromosome in severe Covid-19 cases, most of the media attention centered on the blood-type findings. Among the more than 1,500 Italian and Spanish patients with the coronavirus included in the study, infection appeared to be less common among people with blood type O and more common among people with blood type A. (The type B’s fell somewhere in between.)

The study’s blood-type findings closely mirrored the results of an earlier paper from China, which also found an elevated infection risk among type A’s and lower risk among type O’s. “There are now several studies confirming the association, which is also seen for [SARS],” says Tom Karlsen, MD, PhD, co-author of the new study, and a professor of internal medicine at the University of Oslo in Norway.

SARS and Covid-19 stem from genetically related coronaviruses. So it makes some sense that if a certain blood type is associated with a lower risk for one of these infections, it could also lower a person’s risk for the other. There are also several well-established connections between blood type and infectious diseases; for example, type O blood is protective against malaria but is associated with more severe cases of cholera.

The new Covid-19 findings surely produced some relief in people who are type O and dread in those who are type A. But some experts who have looked at the research say that the findings are questionable — and may ultimately prove to be either inaccurate or misleading.

“I keep getting emails from people asking me if they should get blood typed, and I tell them definitely not!” says Laura Cooling, MD, a professor and associate director of transfusion medicine at the University of Michigan.

Cooling says that some American researchers, herself included, have been looking at…

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Markham Heid
Elemental

I’m a long-time contributor at TIME and other media orgs. I write mostly about health. I grew up in Michigan, but these days I live in southwest Germany.