Covid vaccines: The booster doses of the Covid vaccine are more effective if they are given in the same arm

A study carried out in the USA reveals a better immune response if it is administered in the same extremity

Susan Zamora

It does not matter the arm or the part of the body in which the coronavirus vaccine has been applied, the important thing is that the booster doses have been injected into it. That allows the immune memory cell response to be better than if it was injected into a different limb.

Therefore, protection against Covid-19 is not only given by the characteristics of the vaccine itself or by the number of doses administered to complete the regimen, it has now also been seen that the area of ​​the body where the prick is applied It is also decisive for protection.

This is revealed by research carried out by Duke University (North Carolina) and published in the scientific journal ‘Science Immunology’, which has analyzed the immunization achieved by two groups of mice after receiving a booster dose. While the former were given the injection in the same leg as the first dose, the latter were given the opposite limb.

The results reveal that the creation of antibodies were “similar” for the two groups. However, it was observed that the response was of “better quality” in those who repeated with the same leg. According to the study authors, they exhibited “increased avidity for antigen, higher immunoglobulin mutation frequencies, and greater retrieval of memory B cells.”

Research has shown that these memory B cells, one of those responsible for protecting the body from infections, are capable of causing long-term protection not only systematically, but also by acting locally. A phenomenon that raises the importance of taking into account in which arm each dose is administered to try to force the best possible response.

Scientists have also seen in the test with mice that if they administer a different vaccine in the same paw in the second dose, the B cells acquire the ability to recognize different antigens. On the other hand, if they inject different vaccines into different legs, then the ability of the cells to react to different antigens is reduced.

In any case, this discovery opens the door to weigh in which arm the vaccines are administered in large immunization campaigns, such as those for the flu or Covid-19, which involve the administration of several doses over time for each one. of individuals. “The location of the booster immunization should be considered in vaccination strategies,” the experts who participated in the study concluded.