Democrats push to restore flu vaccine mandate for troops amid Air Force base outbreak

An outbreak at Joint Base San Antonio-Lackland has sickened at least 275 people.

July 1, 2026, 5:56 PM

Three Democratic lawmakers introduced an amendment to a must-pass annual defense funding and policy bill that would require the Pentagon to restore mandatory flu vaccinations for service members.

The proposal on Tuesday, from Reps. Joaquin Castro of Texas, Chrissy Houlahan of Pennsylvania, and Gil Cisneros of California would reverse Defense Secretary Pete Hegseth's April decision to make the annual flu shot voluntary, ending a policy in place since 1945. 

The effort comes after ABC News first reported on a flu outbreak that has sickened a total of at least 275 Air Force recruits undergoing basic military training at Joint Base San Antonio-Lackland since the outbreak started in early June.

Rep. Joaquin Castro attends a rally against the Supreme Court's ruling on temporary protective status outside of the Supreme Court, June 25, 2026.
Kevin Dietsch/Getty Images

Four recruits have been hospitalized, according to Castro and a source with knowledge of the situation who was not authorized to talk to the press. One airman has died, though it remains unclear whether the death was directly related to the outbreak, with the specifics still under investigation, according to the Air Force. 

Basic trainees live, eat and train in close quarters, while the physical demands of training and chronic sleep deprivation can weaken the immune system.

"A [service member] who is sick cannot fight effectively," Castro, whose district includes Lackland, said at a press conference Tuesday. "The flu vaccine is a simple way to make sure troops are healthy and prepared to carry out their mission." 

New recruits are typically not vaccinated until they arrive at basic training, which is their initial introduction to the military. 

Less than two months after Defense Secretary Pete Hegseth ended the military-wide flu vaccine requirement, the services were granted exemptions allowing them to again mandate the shot for large portions of the force, according to an internal document reviewed by ABC News and officials familiar with the situation. 

Secretary of War Pete Hegseth stands during a media statement as he arrives for a NATO Defence Ministers meeting, June 18, 2026, in Brussels, Belgium.
Omar Havana/Getty Images

Those exemptions cover basic trainees across the military branches, service members deploying overseas or participating in major training exercises; personnel working in military prisons, healthcare and childcare; and crews responsible for transporting the president aboard Air Force One -- effectively restoring the requirement for a substantial portion of the military.

Until the new mandate requiring the flu vaccine again, 60% of Lackland Air Force trainees were not vaccinated for the flu, according to the two sources.

But with the new exemption, the Air Force has the goal of vaccinating all of the recruits in this recruit class and will vaccinate all new recruits arriving at the base according to one of the sources.

Vaccines have played a significant role in the history of the U.S. military. In a 1776 letter to his wife, John Adams wrote that smallpox was "ten times more terrible" than the British and indigenous forces, arguing that the disease posed a greater threat to the Continental Army than the enemy itself. 

The Annex Gate entrance sign is seen at Lackland Air Force Base in San Antonio, Texas April 8, 2016.
Darren Abate/Reuters

He blamed a devastating smallpox outbreak for forcing American troops to abandon their campaign in what is now modern-day Canada. George Washington ordered all of his formations to be vaccinated against smallpox the following year. 

That precedent continued to the aftermath of World War I. About 45,000 American service members died from influenza and related pneumonia amid the Spanish flu pandemic during the war -- nearly as many as the roughly 53,000 U.S. combat deaths, according to Pentagon figures. The Army supported the development of a vaccine, which was refined and began to be used widely in 1945. 

"For decades, the military required influenza vaccines for new recruits because military doctors understood a very simple fact: when thousands of young Americans live, train, eat, and sleep in close quarters, infectious disease spreads very quickly," Houlahan, an Air Force veteran, told reporters Tuesday.

Keon McDaniel, the Air Force recruit who died, was in his sixth week of basic training when he experienced a medical emergency on June 12, according to the Air Force. Recruits undergo a medical screening before they can enlist, but that process relies largely on medical history and a relatively limited clinical review.

He was transported to Brooke Army Medical Center, where he subsequently passed away. The cause of the medical emergency is currently under investigation, and a comprehensive medical review is being conducted to determine the facts, according to the Air Force.

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