Can Alternating Arms Improve Vaccine Effectiveness?

By Alana Smart / April 17, 2024 / Blog ,

Can Alternating Arms Improve Vaccine Effectiveness?

Recent research published in The Journal of Clinical Investigation indicates that alternating arms when receiving multiple doses of vaccines may enhance the immune response.

Researchers at Oregon Health and Science University conceived the study during the early days of the pandemic when vaccines were first available and in high demand. As vaccination efforts gained momentum and became widespread by late 2020, participants started to inquire about the potential impact of alternating arms during the two-dose series.

“This question hasn’t really been extensively studied, so we decided to check it out,” Marcel Curlin, M.D., associate professor of medicine at OHSU and the study’s senior author, said. “It turned out to be one of the more significant things we’ve found, and it’s probably not limited to just COVID vaccines. We may be seeing an important immunologic function.”

Some volunteers received both doses in the same arm, while others alternated arms between doses. Researchers meticulously matched 54 pairs of participants for age, gender, and relevant time intervals between vaccination and exposure.

Initially, two weeks after the second dose, there wasn’t a noticeable difference in the immune response. However, after three weeks, blood samples revealed significantly higher antibodies capable of binding and neutralizing the SARS-CoV-2 virus. Over four weeks, these antibody levels progressively increased, reaching up to a four-fold increase against the omicron variant.

Researchers observed a significant improvement in the immune response from three weeks after the second booster until 13 months after. The study showed that the immune system responded strongly to the original SARS-CoV-2 strain and exhibited an even more robust response to the omicron variant that emerged approximately a year after receiving the booster shots.

While researchers are unsure why this happens, they posit that administering a shot in each arm prompts new immune responses in different lymph nodes in each arm.

“By switching arms, you basically have memory formation in two locations instead of one.” 

While the study primarily focused on the COVID-19 vaccine, researchers believe that this finding could potentially benefit other multi-dose vaccines as well. They advocate for further research to confirm whether alternating arms can enhance immune response across various vaccine types.

Many employers dedicated to occupational health and safety commonly integrate vaccinations into pre-employment or annual health services as standard practice. Traditionally,  providers considered the choice of arm for vaccine administration inconsequential. However, this study challenges that notion, suggesting that there is potential for optimizing immune responses by alternating arms for multi-dose vaccines.
Imagine a workplace where vaccinations provide essential protection and enhance immune responses. By potentially incorporating alternating arms into vaccination protocols, employers could bolster the health and resilience of their workforce, contributing to a safer and more productive work environment.



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