IS GETTING COVID-19 SHOTS IN THE SAME ARM BETTER? A new study suggests you may get better protection if your vaccinations and booster shots are in the same arm.

I always get my vaccinations in my left arm. Not because I anticipated the intriguing new study results.

Rather, I sleep on my right side and don’t want the discomfort associated with vaccination on my compressed arm.

Before we examine sidedness and vaccinations, I must share that winter has begun in Seattle. I define the season as dark and rainy.

Chilled-looking people walking along the riverside, the snow beginning, faintly, to pile up on the roofs of cars, the bare trees shaking their heads left and right, dry leaves tossing in the wind. The silver of the metal window sash sparkled coldly. Soon after, I heard sensei call, “Mikage! Are you awake? It’s snowing, look! It’s snowing!” “I’m coming!” I called out, standing up. I got dressed to begin another day. Over and over, we begin again. — Banana Yoshimoto

Arm-Sidedness and COVID Vaccination

I read the title of a recent article and thought, “Really?” But as you will see, there is a logic to the finding. Here’s the title:

Differences in SARS-CoV-2 specific humoral and cellular immune responses after contralateral and ipsilateral COVID-19 vaccination.

In other words, individuals may get more protection against COVID-19 if they get their vaccinations and boosters in the same arm.

The Study

German researchers examined health data for 303 people who got the mRNA vaccine and a subsequent booster shot. None had a history of COVID-19 infection.

They measured the antibody levels of the subjects two weeks after the second shot.

Here are the surprising results:

The number of protective “killer T cells” was higher in the 147 study participants who got both shots in the same arm.

Scientists found killer T cells in 67 percent of cases when both shots entered the same arm. This number compares to 43 percent of cases with different arms.

My Take

Same-arm vaccinations may work better because the cells providing the immune response are in nearby (underarm) lymph nodes.

There may be a more vigorous immune response if the immune cells in the nearby nodes are restimulated in the same location.

Since this study does not represent high-level evidence, we need more studies to validate the results. Moreover, we don’t know if the findings apply to other vaccines, including the flu.

Still, I will continue to get my vaccinations in my left arm. I sleep on my right side, so it is for the best.