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Susceptibility to infection with the Sars-CoV-2 virus can vary by blood group: individuals in group O tend to be at lower risk, while others are also potentially more exposed to serious clinical conditions.
The results of two articles, published on Wednesday (14) by the scientific journal Blood advances, confirm the hypotheses presented since last March.
The University Hospital of Odense, Denmark, carried out a retrospective study, where scientists compared the health records of more than 473,000 individual COVID-19 tests with a control group of 2.2 million, from the general population.
Blood type O was about 13% less likely to test positive for COVID-19 than type A, B, or AB. These results, however, do not imply an increased risk of hospitalization, emphasize the Danish authors.
In another study, from the University of British Columbia, Canada, 95 patients with severe covid-19 were hospitalized in Vancouver. Blood groups A and AB were more associated with a risk of severe disease progression, more frequently requiring artificial respiration or dialysis due to kidney failure. Additionally, types A and AB tended to require longer ICU stays than blood O or B.
It is not the first time that scientific research has linked susceptibility to respiratory diseases and their evolution to blood groups. In March, a study, not subject to independent review (look at review) – concluded in China that carriers of type A blood were more easily infected.
Then, based on the medical data of 750,000 people, the biotech company 23andMe revealed that type O would be between 9% and 18% more exposed to contracting the new coronavirus.
In June, German and Norwegian researchers published the results after following 1,610 critically ill patients from covid-19 epicenters in Spain and Italy. They examined certain stretches of DNA where genetic mutations occur frequently, and the observed characteristics were compared with blood samples from 2,205 healthy individuals.
Those belonging to blood group A showed a 45% higher risk of a severe course, with twice the chance of needing oxygen or artificial respiration. On the contrary, O blood would have a kind of protective effect, which implies a 35% less risk.
Some experts suggest that the association may be due to the different antibodies produced by different blood types, or how they can affect clotting ability. On the other hand, other investigations, such as that carried out by Harvard Medical Schoolin Massachusetts, and in Columbia Presbyterian Hospital, from New York – found no correlation.
Although the Harvard study showed a higher probability between types B and AB, Rh factor positive, of testing positive for the coronavirus, it was also found that even symptomatic patients of blood group O were less likely to show positive test results. .
“These results need to be further explored to determine if there is something inherent in these blood types, potentially capable of providing protection or reducing risk for people,” said lead study author Anahita Dua.
