Which Arm Should You Choose for Vaccines?

Your body might have a favorite arm when it comes to vaccines. It’s just too bad that science can’t agree on which side is better.

It turns out that the side you choose for your COVID-19 shot could influence how fast your immune system absorbs the vaccine. Which arm is entirely dependent on the research team you choose to listen to?

A team of researchers in Germany says that getting jabbed in the same arm over and over again produces a better immune response in the weeks to follow. An American study begs to differ, suggesting that switching arms can quadruple your antibodies.

An Australian study then butts in to side with Germany to say that same-arm shots actually do speed up your body’s immune response but that the advantages don’t last all that long.

The Arm You Choose for Vaccines Makes a Difference

In the Australian study, led by Rama Dhenni and Alexandra Carey Hoppé, 30 COVID-free folks were recruited and jabbed. Some in the same arm twice, others in alternating arms. Blood and lymph node analysis showed that Team Same-Arm kicked antibody production into high gear within a week, while also fending off variants like Delta and Omicron.

So why the sudden surge of immunity in one arm? A vaccine in your left arm rings the alarm in that side’s lymph node only. Hit the same arm again, and that side’s lymph nodes are like “Oh yeah, I remember that” and get right to work producing antibodies.

By week four, both groups—same-arm and switch-arm—had similar antibody levels. So while early protection might be slightly better with consistency, the long-term benefits are pretty much the same. Either way, just get the shot. Your lymph nodes can sort it all out later.