Air Force flu outbreak at Texas training base reaches 222 cases

A flu outbreak at Joint Base San Antonio-Lackland grew to 222 cases and four hospitalizations, forcing Air Force officials to isolate sick trainees and monitor close contacts. The outbreak has lasted about three weeks and is being managed with antiviral medications such as Tamiflu.

The cases have piled up at Basic Military Training on Lackland Air Force Base in San Antonio, where the 37th Training Wing trains more than 36,000 troops a year. Medical professionals and public health officials are treating symptomatic trainees and working to slow further spread, but lawmakers and local officials have begun demanding answers about how the virus spread so far before the service publicly named the full scale.

Rep. Joaquin Castro, a Texas Democrat, said the number had reached 222 as of Thursday and called for a full accounting of what happened. Castro called the decision to end the annual flu mandate “reckless” and said it put troops in harm’s way while undermining military readiness.

The outbreak came after Defense Secretary Pete Hegseth issued an April 20 memorandum making the annual influenza vaccine voluntary for active-duty personnel and Department of War civilian personnel. The policy allowed services to seek exceptions, and the Air Force received permission to vaccinate all trainees. Influenza vaccines have been used by the U.S. military since the 1940s and were required annually for active component service members starting in the 1950s.

A 2025 Defense Health Agency and Armed Forces Health Surveillance Division report found recruits had the highest cumulative seasonal influenza hospitalization rate among active component service members. Outbreaks of this size have become uncommon because recruits traditionally received flu shots before entering basic training. One former Armed Forces Health Surveillance Center official said the last significant comparable outbreak was in 2009-2010.

San Antonio Mayor Gina Ortiz Jones, who previously served as undersecretary of the Air Force, said the outbreak was preventable and criticized what she called the politicization of public health.

Recruit Keon McDaniel suffered a medical emergency during his sixth week of Basic Military Training on June 12 and later died at Brooke Army Medical Center. Whether influenza played any role remains under investigation.