No, Covid-19 vaccines do not change a person's blood type, experts say

No, Covid-19 vaccines do not change a person’s blood type, experts say

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There is no indication that anti-Covid vaccines change the rhesus or the blood group of vaccinated people, explain specialists, contrary to what a voice note shared several hundred times since mid-July on social networks asserts. This phenomenon has never been observed by blood collection establishments and doctors interviewed by AFP. In addition, they explained that in the current state of scientific knowledge, it is impossible for a patient’s blood type to change, except in the case of a bone marrow transplant.

At the beginning of this voice note of almost a minute and a half, shared more than 180 times on Facebook, a man claims to have “two patients, a man and a woman, who, following an operation, were vaccinated with 3 doses, apparently their blood rhesus has changed – something that does not exist – since their third dose”. “All hospitals now know that blood rhesus changes after vaccination. In order not to panic people, they now systematically ask to repeat a blood test for rhesus (…)”, he assures. “And in fact, vaccines from two doses modify the rhesus after 6.8 months and in 3 doses after 2.3 month”.

“This announcement is official, I got it this morning directly from my office”, says the author of this voice note again, without mentioning the name of this firm.

This voice note was relayed in different forms on several social networks in France and Belgium, such as Telegram, Facebook, Twitter, VK as well as on the Odysée platform.

Screenshot made on VK on 08/02/2022
Screenshot taken on the Odysée website on 02/08/2022

AFP interviewed several hematologists, blood collection establishments as well as a union and a federation of doctors. All of them explained that they had never observed or heard of such a phenomenon, nor of systematic blood tests after vaccination, as claimed in the publications we checked.

These specialists explained that in the current state of scientific knowledge, a change in blood rhesus is only possible in the case of a bone marrow transplant.

The blood group is characterized by a gene, located on a chromosome, and by a corresponding antigen on the surface of red blood cells. False claims that vaccines, especially messenger RNA vaccines, can alter the genes of vaccinated people are rampant on social media and have been verified by AFP multiple times, here and again here. AFP has also published verification articles on alleged dangerous blood clotting after vaccination, here for example.

No proven case of change of rhesus after vaccination

The Rhesus system is, along with ABO, one of the main systems for classifying people into different blood groups. The traditional classification of blood groups is formed of the letters A, B or O with positive or negative rhesus. Depending, in particular, on the presence of a certain antigen on the surface of their red blood cells, a person will be part of group A, B, AB, or O.

As for positivity or negativity, it is determined according to the presence or absence of another antigen on the surface of the red blood cells.

As the Belgian Red Cross website explains: “The ABO system allows each individual to be assigned a letter which characterizes their blood group: A, B, AB or O. The Rh system determines whether you are Rh positive or negative”. An O- person will therefore have a so-called “negative” rhesus – the antigen is not present on the surface of the red blood cells – while an O+ person has a so-called “positive” rhesus – the antigen is present.

Contacted on August 2, 2022, the president of the Belgian Association of Medical Unions (ABSyM), Luc Herry, said he had never heard of any change in blood group or rhesus after a vaccination. And contrary to what the author of the voice note claims, “Rhesus is not systematically analyzed after vaccination”he specified. “Knowing whether the patient has a positive or negative rhesus apart from a blood transfusion or a pregnancy is of no interest”.

In France, the president of the French Society of Vascular Medicine (SFMV) and hematologist, Marie-Antoinette Sevestre-Pietri, explained on August 3, 2022 “that none of the members have been in contact with these outlandish claims”adding that in the current state of scientific knowledge, a change in rhesus linked to vaccination “is not possible”.

“We have taken more than 20,000 blood groups since the start of the pandemic and I have not seen any case of rhesus modification in the population. vaccinated”, added Véronique Deneys, hematologist and director of the blood bank at the Saint-Luc university clinics, in Brussels, interviewed on July 27, 2022.

The Belgian Red Cross has also confirmed to AFP that it has never heard of a change in rhesus after one, two or three doses of the vaccine: “To my knowledge, there is no link between the vaccine and the expression of rhesus on the surface of red blood cells. In our daily practice in the blood service in Wallonia, we do not encounter this phenomenon”, declared on August 2, 2022 Tome Najdovski, production manager at the blood service of the Belgian Red Cross. The vaccine “has no action on blood group or rhesus expression. It just causes an immune reaction, so interacts with antibodies.”he specified.

On Twitterthe French Blood Establishment (EFS) also reacted to these claims on July 15.

“The blood type, including rhesus, is congenital and therefore cannot change with the vaccine”, Marie-Agnès Azerad, head of the hematology department at the CHU Saint-Pierre in Brussels, told AFP again on August 1, 2022.

An observation shared by Nicolas Gendron, hematologist at the Georges-Pompidou hospital in Paris, interviewed on July 27, 2022: “The vaccine has no impact on the blood at any level, neither on the level of platelets, red blood cells and white blood cells, nor on their activation”.

In the case of messenger RNA vaccines, which arouse the mistrust of many Internet users, the process consists of injecting a molecule which will deliver genetic instructions to the cells allowing them to develop antigens specific to the virus, and to cause the immune system to produce antibodies to defend against it.

Infographic on the main types of vaccines available to fight a virus ( AFP / John SAEKI)

The National Institute of Health and Medical Research (Inserm) stresses that it It is important to specify that the RNA injected via the vaccine against Covid has no risk of transforming our genome or of being transmitted to our descendants, insofar as it penetrates into the cytoplasm of cells, but not into the nucleus “. However, it is in this cell nucleus that the genetic material is located, on which our blood type depends in particular.

“The messenger RNA vaccine goes into the muscle cells and encodes the spike protein. Nothing happens with the red blood cells. The RNA is a message and doesn’t touch the DNA of the cells,” added Nicolas Gendron.

Only a bone marrow transplant can change a person’s rhesus, according to specialists interviewed by AFP

All the specialists interviewed by AFP explained that the blood group cannot change, with the sole exception of a bone marrow transplant, which is used to cure patients with certain forms of cancer or blood diseases.

The bone marrow is responsible for the production of stem cells, which themselves produce red blood cells, platelets and white blood cells. When it is replaced, these stem cells are then replaced by those of a donor, whose blood group is not necessarily the same as that of the recipient.

“The principle of a bone marrow transplant is to destroy all the marrow of the recipient patient – at the origin of the problem from which he suffers – and to replace it with the marrow of the donor. For example, if one were rhesus positive and you have received bone marrow from someone who is rhesus negative, you can become rhesus negative”explained Véronique Deneys.

Rhesus also comes into consideration in some pregnancies, if the pregnant woman is Rhesus negative and the fetus is Rhesus positive – which may be the case if the father is Rhesus positive. In this case, the incompatibility of rhesus can lead to complications: “The woman can then develop antibodies against the rhesus positive group, which can be a problem in the event of a second pregnancy, where these antibodies can attack the blood cells of the child”, developed Nicolas Gendron.

But it is not a change of blood group: the woman then only develops positive anti-rhesus antibodies.

These antibodies, which also appear in certain cases of viral hepatitis for example, can disturb blood tests and make it more difficult to determine the blood type in the laboratory.

“The patient will then develop antibodies, which will attack his red blood cells. The patient’s blood group will not change, however antibodies will stick to the red blood cells and destroy them, which can make it more difficult the determination of the patient’s blood group”, explained Marie-Agnès Azerad. In this case, the laboratories carry out additional tests in order to determine the patient’s blood group as precisely as possible, without the latter having been modified.


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