Why are a few people infected by the coronavirus becoming seriously ill, while others show little to no signs of the symptoms, or are asymptomatic? The answer might lie in a person's blood group. Recent researches are pointing to the fact that the ABO blood group might play an important role in a person's susceptibility to the virus.
The latest research by genetic-testing giant 23andMe has thrown some interesting points for researchers to ponder about. According to the preliminary data collected by 23andMe, people with O blood group (O-negative and O-positive) are protective against the coronavirus. "O blood type appears to be protective against the virus when compared to all other blood types," the firm states in its report. "Individuals with O blood type are between 9-18 per cent less likely than individuals with other blood types to have tested positive for COVID-19." The report is based on a research conducted on more than 750,000 participants.
While factors like age and underlying health conditions determine how an individual responds to the coronavirus infection, those factors alone do not explain the wide diversity of symptoms, or why some people contract the disease and others do not. That's when researchers became curious about the genetic factor behind the disease.
Several other studies looking at both severity of illness and susceptibility to disease have also suggested blood type plays a role. It’s been suggested that genetics could play a part–with reports that people with type A blood could be at greater risk of suffering serious complications from Covid-19.
According to a study by researchers in China, blood group A (A-positive, A-negative and AB-positive, AB-negative) was associated with a higher risk for acquiring COVID-19 compared with non-A blood groups, whereas blood group O was associated with a lower risk for the infection compared with non-O blood groups.
Another study by researchers in Italy and Spain, on samples from COVID epicentres, revealed that those with A blood group were at higher risk of COVID, while those with O blood group showed more protection against the infection. 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 per cent increase in the likelihood a patient would require a ventilator.
In another study, published online April 11 to medRxiv, scientists looked at 1,559 people tested for SARS-CoV-2 at New York Presbyterian hospital; of those, 682 tested positive. Individuals with A blood types were 33 per cent more likely to test positive than other blood types. Both O-negative and O-positive blood types were less likely to test positive than other blood groups.
However, while these evidences are compelling, these are not conclusive in nature. Why a blood group might increase or decrease a person's risk of getting SARS-CoV-2 is yet to be clear. Perhaps, the only reasoning can come from the theory of antigen--a person's blood type indicates what kind of certain antigens cover the surfaces of their blood cells; these antigens produce certain antibodies to help fight off a pathogen.
