Reacción a "The vaccine booster may be more effective if administered in the same arm"

This is an interesting study on a novel question: when administering booster doses of a vaccine, is it better to do so in the same arm or does it matter which arm is used?

The publication in question finds that administering the booster in the same arm as the previous dose improves the antibody response in the initial phases after administration, although after four weeks the response observed is similar when the booster dose is administered in the same arm or in the opposite arm. It uses a complex methodology involving a first laboratory phase in mice and a second phase with a limited number of human volunteers who receive two doses of a SARS-CoV-2 mRNA vaccine, the second in the same or opposite arm. The authors hypothesise that a subset of memory B cells remain in a specific area of the lymph node located in the region near the injection site and are activated early after the booster dose is administered.

The hypothesis is worth investigating because, if true, it could improve the effectiveness of vaccines at no cost and perhaps reduce the amount of antigen they contain.

However, the issue is far from clear. Other publications have reported preliminary results in the same vein, but others have found the opposite. The answers are therefore still a long way off. It is too early to propose changes to vaccination guidelines establishing that booster doses should be administered in one limb or the other.