Sometimes, amidst the whirlwind of scientific advancements, it’s the simplest solutions that remain overlooked. Since the inception of vaccines over two centuries ago, researchers have delved into various aspects of inoculation, exploring different dosages, vaccine agents, and methods of administration to bolster the immune system against pathogens.
However, one question has largely evaded scrutiny: Does the choice of arm for vaccination make a difference?
Researchers at Oregon Health & Science University (OHSU) suspect it might. The inquiry arose during the early days of the COVID-19 pandemic when healthcare workers involved in vaccine studies queried whether alternating arms between the first and second jab could be beneficial.
It’s a question that hasn’t received much attention.
says infectious disease specialist Marcel Curlin
Upon scouring the scientific literature, Curlin and his team found only a handful of papers on the subject, with mixed results. While one study in infants suggested higher antibody levels when vaccines were administered in different arms, a more recent investigation indicated superior immune responses when COVID-19 vaccinations were given in the same arm.
To shed light on the matter, OHSU researchers assessed the antibody levels of 947 participants who received a two-dose COVID-19 vaccination. Half of the group received both doses in the same arm, while the other half received them in different arms. Four weeks after the second dose, those receiving staggered jabs exhibited 1.4-fold higher SARS-CoV-2-specific serum antibodies.
Further analysis of a matched subset of participants revealed significant differences in antibody levels. Four weeks post-vaccination, individuals receiving shots in both arms displayed up to a four-fold increase in antibodies compared to those receiving shots in one arm. Moreover, this enhanced immune response persisted for over a year after the booster dose.
Curlin hypothesizes that by stimulating an immune response in both arms, the body may be better prepared to detect and neutralize pathogens. This phenomenon likely arises from the distinct drainage pathways of lymph nodes on each side of the body.
While more research is needed, I won’t hesitate to switch arms for my next booster.
Curlin remarks
