People with blood type A more likely to suffer severe coronavirus symptoms, research finds

Anne Gulland
Patients with blood type A were more likely to end up on a ventilator - David Benito/Getty Images
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People with blood type A may be more at risk of serious forms of the coronavirus, new research has shown.

The study, by researchers in Germany and Norway but not yet published in a journal, is the latest to show that people with this particular blood type may be more susceptible to the disease. 

The researchers found two points in the human genome which were associated with an increased risk of respiratory failure in patients with Covid-19. One of these points is the gene that determines blood type.

Having type A blood was linked to a 50 per cent increase in the likelihood that a patient would need oxygen or go on a ventilator, the researchers found.

However, Andre Franke, professor of molecular medicine at the University of Kiel and lead author of the study, said it was not certain whether it was the blood group that determined whether someone would become more seriously ill, or the genetic marker.

“We cannot disentangle yet whether actually the blood group is the risk or some genetic variants that are linked to the blood groups. Using the blood groups as proxies, we estimate a 50 per cent higher protection for [blood type] O and a 50 per cent higher risk for A,” said Prof Franke. 

Researchers took blood samples from 1,610 patients in hospitals in Italy and Spain who needed oxygen or had to go on a ventilator. They extracted DNA and scanned it using a technique called genotyping. 

They then compared these findings with 2,205 blood donors who did not have Covid-19.

They then looked at the DNA of the Covid-19 patients to determine if they shared any of the same genetic code.

Separate studies from China and the United States have also shown that people with blood type A are more susceptible to the disease than those with type O, the more common blood type. 

And during the 2002 to 2003 epidemic of Sars - the coronavirus most closely linked to Covid-19 - researchers also found that those with type A blood were more likely to contract the disease.

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But researchers are still unsure why there is a link. 

Prof Franke told the New York Times that he could only speculate about the reason. “This is haunting me, quite honestly,” he said. 

Sakthi Vaiyapuri, associate professor in cardiovascular and venom pharmacology at Reading University who was not involved in the research, said that different blood groups had different antibodies which may confer protection to some diseases but not others. 

However, he added: “The molecular mechanisms behind this blood group type mediated protection or susceptibility for several diseases are still poorly understood.”

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