Delivering multiple vaccines in both arms, rather than just one, substantially increases antibody responses, new research suggests.
In a review of 947 participants in a larger study about the efficacy of the COVID-19 vaccines, researchers found that "opposite-arm" patients had better results than the "same-arm" group. When the first and second COVID-19 vaccines were administered in different arms, antibody titers were 1.2-fold higher at week two, 1.4-fold higher at week three and 1.4-fold higher at week four.
"It is commonly expected that immune responses are indifferent to ipsilateral [same arm] versus contralateral [opposite arm] boosting as part of a multi-dose intramuscular vaccine regimen," the researchers wrote in The Journal of Clinical Investigation. But, the new findings indicate switching up injection sites can improve patient outcomes.
In conclusion, they said further research is needed, especially among younger populations, since immune responses might differ in children.