Alternating Arms for Vaccines: Boosting Immune Response
In the race to combat COVID-19, researchers are continually exploring ways to optimize the effectiveness of vaccines. A recent study suggests that alternating arms for vaccine doses may enhance the immune response, potentially leading to stronger immunity. While the findings are preliminary and more research is needed, they could have significant implications for future multidose vaccines, including childhood immunizations.
The study focused on the response to the first two doses of COVID-19 vaccines. Researchers observed that individuals who received doses in alternating arms exhibited a small increase in immunity compared to those who received both doses in the same arm. Although the boost in immunity may seem minor, it could be particularly beneficial for individuals who have a poor response to vaccines due to age or underlying health conditions.
Dr. Marcel E. Curlin, an infectious disease physician at Oregon Health & Science University who led the study, emphasized the need for further investigation before making any recommendations. He stated, “I’m not making recommendations at this point because we need to understand this a lot better.” However, he added, “all things being equal, we ought to consider switching up the arms.”
Previous studies comparing the two approaches have yielded mixed results, with no significant difference in immunity observed. Jennifer Gommerman, chair of the immunology department at the University of Toronto, highlighted that most vaccines target a single arm and that extending the interval between doses may offer greater benefits than switching arms. Nevertheless, Gommerman emphasized the importance of studying various strategies to enhance immune responses in immunocompromised individuals.
To investigate the impact of alternating arms on immunity, Curlin and his colleagues conducted a study involving 54 pairs of university employees. The participants were matched for age, gender, and time after vaccination. They were randomly assigned to receive the second dose in the same arm as the first dose or in the opposite arm. Participants who became infected with COVID during the study were excluded from the analysis.
The researchers found that switching arms led to a significant increase in blood antibody levels, up to fourfold. Moreover, this immune response was observed against both the original coronavirus and the omicron variant. Curlin described the effect as consistent, statistically significant, sizable, and durable. These findings initially appear to contradict a German study conducted last summer, which suggested that using the same arm for each dose might yield a better immune response. However, the new study’s results showed a gradual shift over time, with higher antibody levels observed in participants who alternated arms.
Martina Sester, an immunologist at Saarland University in Germany, acknowledged that the new study’s results align with one of the possibilities she had considered. She stated, “What they see is one option I had in mind as a possibility, so in a way that’s interesting that they actually observe this sort of switch in the effects.” Sester believes that alternating arms could be one of several measures that contribute to a successful immune response.
While the COVID-19 pandemic has prompted extensive research into vaccine efficacy, it is important to note that the results of this study may not have immediate implications for the current stage of the pandemic. As most individuals have already received multiple vaccine doses or experienced infections, the benefits of alternating arms for COVID-19 vaccines may be limited. However, if further research confirms these findings, they could shape future vaccination strategies and have broader implications for multidose vaccines.
In conclusion, the study suggests that alternating arms for vaccine doses may enhance the immune response. Although more research is needed to fully understand the implications, these findings could potentially improve vaccine effectiveness, particularly for individuals who respond poorly to vaccines. As scientists continue to explore ways to optimize vaccination strategies, alternating arms may become one of several measures adopted to bolster immune responses.
