Study Suggests Getting COVID-19 Vaccine Shots in Both Arms Boosts Immune Response
In the quest to maximize the effectiveness of COVID-19 vaccines, researchers have stumbled upon an intriguing finding: getting a shot in both arms may enhance the body’s immune response to the virus. While more research is needed to confirm this method’s efficacy and determine if it should be widely recommended for future vaccines, the initial results are promising.
Previous studies on the impact of arm choice on immune response have yielded mixed results, with some showing positive or neutral effects and others indicating a negative effect. However, these studies were limited by small sample sizes or observational designs, making it challenging to establish a cause-and-effect relationship.
The recent study, led by researchers from Oregon Health & Science University, overcame these limitations by analyzing data from a large research project. Participants in this project were randomly assigned to receive the original COVID-19 shots in one arm or both arms, allowing the researchers to track their immune responses over a 14-month period. The study also assessed participants’ responses to the earliest versions of the coronavirus and the initial Omicron variant, which are still circulating today.
The immune responses of nearly 1,000 participants were analyzed in the study. All participants had confirmed negative COVID-19 antibodies before vaccination. The researchers found that those who received the second shot in their other arm produced slightly more antibodies to the coronavirus. This enhanced response was observed for both the spike protein, which facilitates viral invasion of cells, and other parts of the virus. Moreover, the difference between the two groups grew larger over time, potentially explaining why previous studies focusing solely on initial immune responses failed to identify clear benefits for different-arm shots.
The study also compared 54 pairs of individuals matched in age and other characteristics. Although antibody levels were initially similar between the two groups, those who received shots in both arms eventually produced greater amounts of binding and neutralizing antibodies. These antibodies play a crucial role in containing or even preventing infection, including against the Omicron variant.
The authors of the study noted, “In previously unexposed adults receiving an initial vaccine series with the Pfizer/Biotech COVID-19 vaccine, contralateral boosting substantially increases antibody magnitude and breadth at times beyond 3 weeks after vaccination.” The findings were published last month in the Journal of Clinical Investigation.
While further studies are necessary to validate these results and determine if a dual-arm strategy is optimal for all diseases, a 2022 study in mice suggested that a booster flu shot in the same arm was more effective for immunity. However, assuming that the observed effect holds true for at least some infections, the modest boost in immune response could be particularly significant for immunocompromised individuals. If enough evidence accumulates, it may eventually lead to a paradigm shift in how vaccines are administered.
Lead author Marcel E. Curlin, an infectious disease physician at Oregon Health & Science University, emphasized caution in making recommendations based on the current findings. He stated, “I’m not making recommendations at this point because we need to understand this a lot better. [But] all things being equal, we ought to consider switching up the arms.”
In conclusion, the study’s preliminary findings suggest that receiving COVID-19 vaccine shots in both arms may enhance the body’s immune response. While more research is required to confirm these results and determine their broader applicability, this discovery could have significant implications for future vaccination strategies. By optimizing immune responses, we may be able to better protect individuals, especially those with compromised immune systems, from COVID-19 and other infectious diseases.
