36% of French people are of the O + blood group. These individuals can only receive blood from group O and can only donate blood to rh positive (RHD +) subjects. Some studies show that group O carriers are better protected against infection with covid-19.

One of the most widespread groups in France

In France, the O + blood group is the second most common blood group (behind the A + blood group) since it is the blood group of nearly 36% of French people (against 37% for the A + group). As a reminder, the rarest blood groups are groups B and AB which respectively concern only 1% of the French population.

Receiver only from group O

A group O subject has neither the A antigen nor the B antigen. He can therefore only receive blood from group O because his serum contains anti-A and anti-B antibodies. In the presence of red blood cells of blood groups A, B and AB, the antibodies destroy them as if they were attacking a virus. We are talking about hemolysis.

Donor only for Rhesus + groups

A subject in the O + group has rh positive (RHD +). He can therefore only donate blood to subjects with the same rh (RHD): only individuals A +, B +, AB + and O + can receive his blood. Red cells. In France, rh positive (RHD +) are much more frequent than rh negative (RHD-). Indeed, nearly 85% of French people have a positive rh.

As a reminder, the Rhesus system (RHD) is determined according to the presence or absence of the D antigen on the red blood cells. If we find the substance D which is an antigen on the surface of blood cells, the rhesus is positive (RHD +). When there is no substance D on the surface of red blood cells, the rhesus is negative (RHD-).

The blood group of an individual corresponds to the antigens present or absent on the surface of its red blood cells. A blood group has a set of properties that allow to classify individuals in order to define an optimal compatibility during a blood transfusion.

Blood groups are transmitted hereditarily, according to the laws of genetics. The best known blood group system is the rhesus system as well as the ABO system (which includes groups A, B, AB and O), identified in 1901 as Karl Landsteiner (1868-1943), physician and biologist.

Since the start of the Covid-19 pandemic, the scientific cohort has been interested in the link between the blood group of individuals and the risk of developing covid-19. According to INSERM, in one year, around forty studies have been published on the subject. Some of this work has notably pointed to a reduced risk for people with blood type O.

These results have already been confirmed by several meta-analyzes.

Other genome-wide association studies carried out in patients hospitalized for Covid-19 compared to healthy individuals also point in the same direction. This work shows that two regions of the genome were notably associated with the risk of infection, including an area of ​​chromosome 9 carrying the ABO gene which determines the blood group.

Please note, the fact of belonging to the O blood group does not in any way exempt from barrier gestures, the usual measures of social distancing and vaccination. Group O individuals can be infected and also transmit the virus.