One study claims people with Type A blood may be at a higher risk of catching coronavirus and of showing severe symptoms while people with Type O blood may be less vulnerable.
Previous papers show that specific blood types may influence the person’s risk of contracting other diseases, including cancer. Laure Segurel, a human evolutionary geneticist and a researcher at the National Museum of Natural History in France, said: “I think it’s fascinating, the evolutionary history, even though I don’t think we have the answer of why we have different blood types.”
But it is not just humans who have blood types.At least 17 different kinds of primates including chimpanzees and gorillas were found to have different blood types.
Evolutionary biologists found that blood types date back 20 million years to a distant ancestor humans had in common with primates.
Ms Segurel said. “A lot of primate species … also have the differences of being A, being B, being AB.”
Whether it’s a great ape or a new world monkey, it’s quite intriguing that the differences have been found or maintained in so many different species.”
Ms Segurel explained that blood types give humans some kind of evolutionary advantage.
She added that the ABO blood type is present in a range of tissues and organs such as the digestive or respiratory system.
Ms Segurel said: “The evolutionary interest of maintaining these (blood) types might not be related to their function in the blood but likely to their function in respiratory or digestive tissues.
“They are the two places where you have most contact with viruses and bacteria — the places where you inhale the air and the digestive tissue.”
If you imagine a cocktail of pathogens … there could be a cycle of sometimes B being advantageous, sometimes it’s A.”
Cycling through those different preferences and you end up with a population with different blood types.”
While various studies have shown a connection between blood types and coronavirus, most were only carried out on a small group of people and some were not peer reviewed.
A team of European researchers who published their report in the New England Journal of Medicine in June found people with Type A blood had a 45 percent higher vulnerability to catching the virus than people with other blood types.
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The researchers observed more than 1,900 severely ill Covid-19 patients in Spain and Italy, and contrasted them with 2,300 people who were healthy.
Dr Anahita Dua of Mass General, who led the study team, said: “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.”
There are two theories about the connection between blood groups and coronavirus, according to Jacques Le Pendu, research director at Inserm, a French medical research body.
One is that people with type O are less at risk of coagulation problems and clotting has been found to have considerable influence on the severity of the disease.
He said it could also be due to the likelihood that the pathogen will carry the infected person’s blood group antigen.
As such, the antibodies generated by a person with blood group O might disable the virus when transmitted from a person with blood group A.
But he said: “However, this protection mechanism would not work in all situations.
“A blood group O person could infect another blood group O person for example.”