April 21, 2026

2 min read

Add Us On GoogleAdd SciAm

Hegseth says U.S. military no longer requires flu vaccination, drawing criticism from health experts

The decision to no longer enforce mandatory annual flu shots for military personnel could mean more troops will get sick during flu season, one expert says

By Jackie Flynn Mogensen edited by Claire Cameron

U.S. Secretary of Defense Pete Hegseth speaks during a press briefing at the Pentagon in Washington, D.C., on April 16, 2026.

SAUL LOEB/AFP/Getty Images

Join Our Community of Science Lovers!

I agree my information will be processed in accordance with the Scientific American and Springer Nature Limited Privacy Policy. We leverage third party services to both verify and deliver email. By providing your email address, you also consent to having the email address shared with third parties for those purposes.

Updated 44 minutes ago

The U.S. military will no longer require service members to be vaccinated against the flu, Secretary of Defense Pete Hegseth said in a social media post on Tuesday, a decision that some health experts say could endanger troops.

“The War Department is once again restoring freedom to our Joint Force. We are discarding the mandatory flu vaccine requirement, effective immediately,” Hegseth wrote in the post.

The policy stands in contrast to the current recommendations of the U.S. Centers for Disease Control and Prevention (CDC), the country’s highest public health body, which says all Americans over the age of six months who do not have contraindications should get the annual flu shot. The CDC estimates that the vaccine saved some 12,000 lives and prevented about 180,000 hospitalizations during the 2024–2025 flu season.

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

“Flu vaccines are the best tools we have to protect people from severe disease,” says Jennifer Nuzzo, a professor of epidemiology at Brown University. The vaccine might not always prevent the flu, but it effectively lowers the risk of hospitalization and severe disease, she explains.

“I can’t understand why you would make this decision if troop readiness was important,” says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. The data behind the flu vaccine are “clear and compelling” on both safety and the vaccine’s ability to reduce serious illness hospitalizations and deaths, he says. “The data have been repeatedly confirmed to show that across all ages.”

Notably, some of the first reported U.S. cases of flu during the 1918 pandemic were in soldiers from Kansas who carried the virus with them into their camp, where it then is believed to have spread to the rest of the country and on to the rest of the world.

“In the military, vaccination is not political theater. It is force protection. Troops live and work in close quarters, where influenza can spread quickly and sideline otherwise healthy service members,” Richard Ricciardi, a professor at the George Washington University School of Nursing, who served in the U.S. Army for more than three decades, told CNN.

“If fewer military personnel are vaccinated against the flu, it would likely mean more troops getting sick during the flu season, which would compromise the battle readiness of our armed forces and increase the health care costs that the U.S. government pays,” Nuzzo says. “With an increasing number of global engagements that seems like a particularly shortsighted policy.”

Editor’s Note (4/21/26): This is a breaking news story and will be updated.

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, chal