Flu outbreak hits Air Force training base after vaccine mandate ends

A flu outbreak has swept through Joint Base San Antonio-Lackland, sickening about 150 to 160 service members and trainees only weeks after Pete Hegseth ended the military’s annual flu-shot mandate. The timing has sharpened questions about whether a policy change made for ideology and medical autonomy carried predictable costs for readiness at the Air Force’s busiest training pipeline.

Hegseth announced on April 21, 2026, that the annual influenza vaccine would be voluntary for all active and reserve component service members and Defense Department civilian personnel. He said the change took effect immediately and described it as restoring “medical autonomy” and religious freedom, while also calling the prior requirement an “absurd, overreaching” mandate. The Pentagon had required flu vaccination annually for U.S. military personnel since the 1950s, and it generally aimed to inoculate more than 90% of active-duty personnel.

The move came after the Defense Department’s earlier COVID-19 vaccination policy, which ran from Aug. 24, 2021, to Jan. 10, 2023, and led to more than 8,000 involuntary separations for service members who refused the shot. By September 2025, the Pentagon had already begun edging toward a more flexible flu policy, saying the vaccine was only necessary in some circumstances and adding exemptions for reservists.

The outbreak hit a facility where any illness can ripple quickly through the force. Joint Base San Antonio-Lackland is the Air Force’s basic military training site, known as the Gateway to the Air Force and Space Force, and the 737th Training Group there trains more than 36,000 recruits annually. The Air Force said symptomatic trainees were receiving care, including antiviral medications such as Tamiflu.

That response underscores the operational stakes. Military public-health guidance says flu can cause lost duty time, and all flu-related hospitalizations must be reported. The CDC says everyone 6 months and older should get a flu vaccine every season, with rare exceptions. At a base built to turn civilians into Airmen and Guardians, the outbreak has revived a central question: whether loosening a long-standing force-protection measure made the military more vulnerable just when it could least afford avoidable illness.