They find evidence that the blood type plays an important role in suffering the COVID-19

Research by genetic testing company 23andMe has found that differences in a gene, called the ABO gene, that influences blood type can affect susceptibility to the coronavirus.

Scientists at this genetic testing giant have been looking at 750,000 tests (and they're not done yet) for genetic factors to try to determine why some people who contract the new coronavirus don't experience symptoms while others become seriously ill. .

Preliminary results from a study launched last April that sought to use the millions of profiles in its DNA database to shed light on the role of genetics in disease suggest that people who have blood from the type O are more protected against the coronavirus.

According to data published by 23andMe, people with blood type O are between 9% and 18% less likely to test positive for Covid-19 than people with other blood types. These findings hold when adjusting for age, sex, body mass index, and ethnicity.

Although the study found that blood group O was only protective among rhesus-positive blood types, differences in rhesus factor (blood type + or -) were not significant in the 23andMe data. Nor was it a factor of susceptibility or severity in the cases. Additionally, among people exposed to the virus, healthcare and other frontline workers, 23andMe found that blood type O is similarly protective, but the proportion of cases within the strata is higher.

Among respondents to the 23andMe study, the percentage reporting a positive test for Covid-19 is lowest for people with blood type O. The percentage reporting a positive test for Covid-19 was highest among those with blood type AB.

Both blood type data and preliminary genetic findings also appear to support a variant in the ABO gene associated with reduced risk. At least two recently published studies, one from researchers in China and the most recent from researchers in Italy and Spain, have looked at the role of the ABO gene in Covid-19. The study in China looked at susceptibility, while the Italian and Spanish study found an association with blood type and disease severity.

That study looked at the genes of more than 1,600 patients in Italy and Spain who experienced respiratory failure and found that having Type A blood was linked to a 50% increased chance that a patient would require a ventilator. For its part, the study in China delivered similar results regarding the susceptibility of a person to Covid-19.

"There have also been some reports of links between Covid-19, blood clotting and cardiovascular disease," says Adam Auton, lead researcher on the 23andMe study. Despite the interesting results, Auton has warned that there is still a long way to go, "even with these sample sizes, it may not be enough to find genetic associations."

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