Sign up for TPR Today, Texas Public Radio's newsletter that brings our top stories to your inbox each morning.
U.S. Representatives Joaquin Castro of Texas, Chrissy Houlahan of Pennsylvania and Gil Cisneros of California announced Tuesday they have filed an amendment to the National Defense Authorization Act (NDAA) that would once again require influenza vaccinations across the armed forces.
The proposal comes after an outbreak at Lackland Air Force Base spread rapidly through basic military training, where recruits live and train in close quarters. Castro said there are now 284 confirmed flu cases, four hospitalizations, and one death at Lackland.
Trainee Keon McDaniel from the 737th Training Support Squadron died on June 16. Following Tuesday's press conference, the Air Force acknowledged that McDaniel's death at Lackland was caused by the flu virus that swept the base, according to Castro.
U.S. Defense Secretary Pete Hegseth called the flu mandate "irrational" and "absurd."
"What's absurd about keeping those who serve our nation safe?" asked Castro. "No president or secretary should be able to play politics and put the health of our troops at risk."
The Pentagon made annual flu shots voluntary for all military personnel in April after Hegseth ended the longstanding requirement, saying mandatory influenza vaccinations "weaken our war-fighting capabilities." Flu vaccinations had been mandatory for U.S. servicemembers since the 1940s.
Castro said the recent outbreak underscores why the requirement should be restored.
"Despite this outbreak of flu at Joint Base San Antonio Lackland, this Congress, the Republican majority, has refused to even allow an amendment to the NDAA to reinstate that flu vaccine mandate," Castro said during a Capitol Hill news conference.
Houlahan, a former Air Force officer, said abandoning mandatory vaccination ignores both military experience and public health evidence.
"How ridiculous is it that we are standing here literally in the midst of a flu outbreak at one of our most major training bases, and we are turning aside from evidence, and from knowledge, and from science," she said.
Cisneros, a Navy veteran and member of the House Armed Services Committee, criticized Hegseth's decision to make the vaccine optional.
"Secretary Hegseth is not a doctor, and he should not be deciding what vaccine service members should be required to take. Any policy affecting our service members' quality of life should be guided by science, not by fringe theories," Cisneros said.
The amendment would require annual influenza vaccinations through the NDAA, the defense policy bill Congress considers each year.
Public health experts have said the outbreak was predictable after the Pentagon relaxed its vaccination policy. Dr. Luis Ostrosky, chief of infectious diseases at UTHealth Houston, told Texas Public Radio that military training environments are especially vulnerable to the rapid spread of respiratory illnesses because recruits live in close quarters.
In response to the outbreak, the Pentagon partially reversed course in June, allowing each military branch to once again require flu vaccinations for trainees. However, the vaccine remains voluntary for most active-duty servicemembers.
Castro, Houlahan and Cisneros argue that restoring the requirement for the entire force is necessary to protect military readiness and prevent future outbreaks.
Congress is expected to debate the National Defense Authorization Act, including proposed amendments, in the coming weeks.
Copyright 2026 Texas Public Radio