We knew that members of the O-blood group were universal donors, they could also have an advantage in the face of the coronavirus pandemic.
As had noticed a first study carried out in March 2020 in three hospitals in Wuhan and Shenzhen, in the heart of the outbreak from which the Covid-19 had emerged, the O blood group would have a “significantly” lower risk of contracting the virus. Of the 2,173 patients with SARS-CoV-2, the results showed that blood group A was associated with a higher risk of contracting Covid-19 (+ 20%), while blood group O was associated with a lower risk of infection (-33%).
Since this very first study on the link between blood group and coronavirus positivity, many scientists have worked on the subject in Denmark, in the United States, Great Britain or Belgium. Immunologist Jacques Le Pendu, research director at Inserm and the University of Nantes, has “around forty”.
A few days ago, with other specialists, he was able to publish in the journal Viruses a study linking blood groups and Covid.
“25% less risk of infection for group O”
The main conclusion of this study shows that patients with blood type O are better protected against Covid-19. To do this, they relied on thousands of data from many countries.
“The O blood group seems protective compared to non-O types”, explains, in its conclusion, this study by researchers from Inserm and the University of Nantes (Loire-Atlantique).
“All the studies converge, people with blood type O are less susceptible to coronavirus infection,” confirms France Pirenne, medical director of the French Blood Establishment (EFS) in Île-de-France and professor at the university Paris-Est-Créteil. With her team, she is currently carrying out a study in this direction on 300 patients.
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According to Anne Goffard, professor in virology at the Faculty of Pharmacy of Lille and at the University Hospital, the individuals of group O “would have about 20% less chance of being infected”, she thinks, “with all the caution that is essential ”. A figure that varies according to the country where the studies are carried out between less than 10% and 33%. This explains the study by Jacques Le Pendu, for whom, in Western Europe, including France, the risk of infection will decrease by 25%.
How to explain it?
To find a reason for this lower level of infection, the researchers hypothesized. We must go back to the characteristics of blood groups. The individuals of group O naturally have antibodies A and antibodies B. While those of group A have only antibodies B and conversely those of group B have only antibodies A. Those of group AB have no both.
If they are contaminated by a person of group A or group B, the antibodies of the person of blood group O “could eliminate the virus”, launches Jacques Le Pendu.
“However, when SARS-CoV-2 is in the body of a group O, it has more difficulty attaching to receptors”, attempts to popularize Professor France Pirenne.
Another hypothesis led by Anne Goffard: these antibodies naturally present in group O would have an effect on the Spike protein, which allows the coronavirus to enter human cells. In Lille, the virologist explains: “They prevent the Spike protein from recognizing the lung cells to be infected”.
What consequences in France?
According to doctors, this is not the first time that belonging to a blood group favors or disadvantages patients in the face of certain pathologies.
“We also know that women after pregnancies or children produce a lot of antibodies. These people, including those in group O, could have even better results against this virus, ”notes France Pirenne.
The distribution of blood groups in the population would thus have an effect on the virality of the coronavirus. In France, according to the French Blood Establishment, 44% of the population belongs to blood group A, 42% to group O, 10% to group B and 4% are AB.
This may also explain why the rate of contamination varies from one country to another. “O’s are less contaminated by A’s and B’s. Countries with the fewest O people or a good distribution, such as South Korea and Japan, have a virus that spreads less,” explains Professor Le Pendu. immunologist. The barrier gestures are then very effective. On the other hand, we saw the devastation of the Covid in Manaus in Brazil where the vast majority of the population was from the O group. ”The O contaminated each other.
“We can also imagine that by stimulating the immunity of people with blood type O, they could develop even more antibodies to face the Covid. It would be preventive, ”says France Pirenne.
Fewer severe cases in group O members
However, all these specialists want to be cautious and still use the conditional for what “is only a hypothesis”.
“All the studies done so far are just observations on samples. We are carrying out a study at the Institut Pasteur in Lille to try to reproduce the biological mechanism and try to explain these lower risks, ”reveals Anne Goffard. The results are not expected until 2022.
In the meantime, the work of Inserm, like other studies, tends to prove that once infected with Covid, the members of group O hospitalized will have “fewer serious forms”. “We know that these individuals have lower blood clotting factors. Yet it is often one of the aggravating factors of the coronavirus, ”confirms France Pirenne, the blood specialist at the EFS Île de France.
At the heart of hospitals, if “we have heard of this theory”, as confirmed by a laboratory assistant from a large establishment, we remain more cautious.
“It’s like saying that smokers are less affected … The blood group may be a protective factor, but in practice, it does not change much in intensive care”, breathes Jean-Daniel Lelièvre, head of the disease department infectious diseases at Henri-Mondor hospital in Créteil (Val-de-Marne).
“It is important not that members of this blood group feel protected! », Insists France Pirenne, followed by all his colleagues.
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