Which vaccine works best for people who are obese?

About 42% of Americans are classified as obese (defined as having a body mass index (BMI) over 30). Obesity is one factor that can put people at higher risk of having a serious case of COVID-19. 

Some research has suggested that vaccines in general might be less effective for people with higher BMIs. There has been one prior clinical trial (including about 1,000 people) showing that people with obesity were twice as likely to get the flu after getting the flu vaccine as compared to people without obesity. (However, both groups were more than 90% protected against the flu). And researchers have wondered if people with obesity might not respond as well to the COVID-19 vaccine.

What did the COVID-19 vaccine clinical trials find?

All of the clinical trials assessed whether the vaccines worked well in people with obesity. In general, the vaccines were very effective in all patient groups, including those with higher BMIs.

  • In the Pfizer/BioNTech trial about 35% of the trial participants were obese. The vaccine worked just as well in obese people compared to their non-obese peers. (95.4% vaccine efficacy for obese participants vs. 94.8% vaccine efficacy for non-obese participants).
  • In the Moderna trial, they looked at the subgroup of trial participants with severe obesity (BMI over 40). About 6.5% of the trial participants met the criteria for severe obesity, and vaccine efficacy was 91.2% for this group. Vaccine efficacy was 94.5% for the overall trial.
  • Just under one-third of participants in the J&J trial had obesity (28.5%). Vaccine efficacy was 66.8% after 14 days for people with obesity, compared to 66.1% vaccine efficacy overall.

From these numbers, it’s clear that all three authorized vaccines worked well for everyone, regardless of their BMI. So no matter your weight or height, the best vaccine for you is the vaccine that you can get right now!

Last update: April 8, 2021, 1:16pm ET

Science review: HAY, JAB