People of blood group A are at higher risk of developing respiratory complications from Covid-19, while those of blood group O are the least affected, say researchers in several studies, including one in Spain and Italy that was pre-published in the New England Journal of Medicine.
The blood group can play an important role in the development of a severe form of Covid-19, researchers concluded after analyzing 1,980 patients in Italy and Spain. Their study was pre-published in The New England Journal of Medicine.
Are people of one blood group more exposed than others to Covid-19?
Three other independent studies conducted by Columbia University, the University of Mazandaran in Iran, and various Chinese institutions all came to similar conclusions.
People belonging to group A are more exposed to the risk of developing a severe form of the disease, while those who are less at risk are from group O, according to the results of independent studies carried out by these different teams. Compared with those in group A, the risk is lower for patients from other blood groups, B and AB. However, it remains higher than with those of group O.
The pathogenesis of severe Covid-19 and associated respiratory complications is still not evident, but higher mortality is always linked to advanced age and being a man. In addition, patients who also have risk factors (hypertension, diabetes, obesity, and cardiovascular disease) are more likely to develop Covid-19.
At the moment, the relative role of clinical risk factors in determining the severity of the coronavirus has not been clarified, scientists say. They also underline the preliminary nature of the results of these studies, which need to be verified.
Earlier, Chinese scientists had suggested in mid-March, based on a review of data from three hospitals in Wuhan and Shenzhen, that people of blood group A were the most likely to be infected and to have more severe symptoms than others.
U.S. researchers have stated that the people most likely to contract Covid-19 are of blood group AB. People with blood group O were 9 to 18% less likely to test positive for Covid-19 compared to other groups. Conducted by the American biotechnology company 23andMe, the study was carried out on more than 750,000 participants, 10,000 of whom had been hospitalized and diagnosed with Covid-19.