Injection of covid vaccine into different arms enhanced the immune response
US researchers have found that injecting the first and second doses of a mRNA vaccine against SARS-CoV-2 coronavirus into different arms produced a stronger immune response than injecting a booster into the same arm. A publication about this, which contradicts the findings of another research team, appeared in the Journal of Clinical Investigation.
To have a sufficient effect, mRNA-based covid vaccines require the injection of at least two doses of the drug. Typically, health care providers administering the vaccinations do not give importance to which arm the second dose is injected into - there are no clinical guidelines on this.
The study by Marcel Curlin of Oregon Health & Science University and colleagues involved 947 people aged 24-84 (mean 44.5) years who received at least two doses of Pfizer's mRNA vaccine BNT162b2, BioNTech. 507 participants were injected into the deltoid muscle of the upper arm of one arm; the other 440 were injected into different arms. Serum levels of specific immunoglobulins to spike protein, receptor-binding domain (RBD) and virus nucleocapsid, as well as neutralizing antibody titers against SARS-CoV-2.D614G (early strain) and SARS-CoV-2.B.1.1.529 (omicron) were measured in all of them at 0.6; 8 and 14 months after the booster dose.
By month 14, those who received injections in different arms had on average 1.4-fold higher levels of total spike-specific immunoglobulin (p < 0.001). A similar trend was seen for RBD-specific immunoglobulin G. The researchers also matched 54 pairs among the participants who matched in sex, age, and administration intervals, but who received the injections differently. Those who were vaccinated in different arms had higher titers of binding and neutralizing antibodies and progressively increased over time from 1.3-fold (total immunoglobulin; p = 0.007) to four-fold (neutralizing pseudovirus B.1.1.529; p < 0.001) by the time of the last examination.
It is worth noting that another research group had previously reached opposite conclusions. In their work, injection of two doses of BNT162b2 into the same arm did not increase levels of spike-specific immunoglobulin G and its avidity, but did increase neutralizing activity. On the basis of previous experiments on mice, the authors of that work suggested that such an effect was due to the involvement of the same axillary lymph nodes. More extensive clinical and immunologic studies are needed to resolve the controversy.