If you’ve presented the same arm for every dose of a particular vaccine, you may want to reconsider. Alternating arms may produce a more powerful immune response, a new study suggests.
The researchers studied responses to the first two doses of Covid-19 vaccines. Those who alternated arms showed a small increase in immunity over those who got both doses in the same arm.
For individuals who respond poorly to vaccines because of age or health conditions, even a small boost may turn out to be significant, the researchers said. At this point in the pandemic, with most people having had multiple vaccine doses or infections, alternating arms for Covid vaccines may not offer much benefit.
Yet if confirmed by further study, the results could have implications for all multidose vaccines, including childhood immunizations.
“I’m not making recommendations at this point, because we need to understand this a lot better,” said Dr. Marcel E. Curlin, an infectious disease physician at Oregon Health & Science University who led the work.
But “all things being equal, we ought to consider switching up the arms.”
The few studies comparing the two approaches have been small and have produced mixed results. And none of the studies shown a big difference in immunity.