The U.S. Army, Navy and Air Force have reinstated mandatory influenza vaccinations for new recruits, reversing a policy change implemented earlier this year by Defense Secretary Pete Hegseth after military health officials linked the absence of flu immunization requirements to outbreaks at several training facilities.

The Pentagon has updated their guidance on influenza vaccinations, giving select forces and agencies exceptions to the optional policy.

After a trainee died following a flu outbreak at Air Force basic training, the Pentagon issued exceptions to "safeguard at-risk populations."