Beyond just comfort, choosing a different arm for each vaccine dose could impact the effectiveness of the immune response, as revealed by a recent study conducted by researchers at Oregon Health & Science University (OHSU). The findings of this research could potentially change how we vaccinate, especially during the Covid-19 pandemic and its variants.
Against Covid-19, alternate arms during your vaccinations While the choice of which arm to use for vaccine injections hasn't always been emphasized, this new research indicates that the selection of the arm for the second dose – either in the same arm as the first dose or in the opposite arm, a method called "contralateral stimulation" – may affect the effectiveness of the immune response generated against viruses, including COVID-19 and its variants like Omicron.
Researchers at OHSU have discovered that alternating arms for each dose of a multi-dose vaccine, such as the COVID-19 vaccine, could indeed enhance the body's immune response up to four times. At least, that's what the results of this study conducted on 947 individuals suggest.
This new way of getting vaccinated could change everything for people afraid of needles An effective method for many other vaccines? After analyzing serum samples taken at various intervals after COVID-19 vaccination, researchers observed a marked improvement in the immune response in individuals who received their injections in alternating arms.
This boosted immunity was significant not only against the original strain of the SARS-CoV-2 virus but also showed an even stronger response to the Omicron variant. "By switching arms, you essentially have memory training in two places instead of one," explains Dr. Marcel Curlin, lead author of the study and associate professor of medicine (infectious diseases) at the OHSU School of Medicine and medical director of OHSU Occupational Health, in a university press release.
In doing so, this could stimulate new immune responses in the lymph nodes of each arm. This dual-site memory training could be the key to the enhanced immune response observed. The study's results showed that while there was little difference in the immune response two weeks after the second dose, a significant increase in antibodies capable of neutralizing the virus was evident three weeks later, increasing up to four times against the Omicron variant over four weeks.
The research team believes that this phenomenon may not be limited to COVID-19 vaccines alone but could also apply to other mandatory multi-dose vaccinations.