A significant flu outbreak has sickened at least 275 recruits and hospitalized four individuals at Lackland Air Force Base in Texas, leading to the reinstatement of mandatory flu vaccinations for military personnel. The outbreak began earlier this month within a training wing where hundreds of recruits live, eat, and train in close proximity.
The number of confirmed cases rose from 160 last week to 275 as of Wednesday. While one recruit died in a military hospital due to an unspecified 'medical emergency' shortly before the outbreak's severity became apparent, it remains unclear if this death is directly linked to the flu outbreak.
Policy Shift on Vaccine Requirements
This development comes after Defense Secretary Pete Hegseth announced in April that troops would no longer be required to receive annual flu shots, a policy that had been in place since the 1950s. However, Pentagon officials have confirmed that all branches of the U.S. military will now require flu vaccinations for recruits. This decision allows for exceptions to the April policy change.
A congressional staffer indicated that by early May, all military departments had formally requested exemptions to continue mandatory flu vaccinations for certain service members, and these exemptions were granted in early June. Sean Parnell, the Pentagon's top spokesperson, stated that the Defense Department had "granted [exceptions to the policy]" to enable mandatory vaccines for specific military populations. Parnell added that these decisions were based on "thorough risk assessments" and are intended to "maximize operational readiness, lethality, and force generation, while safeguarding at-risk populations."
Approximately 60 percent of trainees at Lackland who were previously unvaccinated reportedly declined the flu shot during the period when the mandate was lifted. The new exemption for the Air Force aims to vaccinate all recruits in the current training class and all new arrivals.
Air Force officials described the recent outbreak as "localized" to the training wing and stated that medical personnel are monitoring the situation and offering antiviral medication to those who were in contact with sick individuals.
When the end of the vaccine requirement was announced in April, Secretary Hegseth stated his department was "restoring freedom" to the forces, criticizing the prior administration's policies as an "unrelenting war on our warriors." He claimed service members were forced to choose between "their conscience and their country."
Lackland Air Force Base's 37th Training Wing processes over 37,000 trainees annually. The decision to end the flu vaccine mandate in April had drawn criticism, with Senator John Wicker, chair of the Senate Armed Services Committee, calling it a "mistake" at the time. He contrasted the flu vaccine, which he described as safe and having a long history of use, with COVID-19 vaccines, which he characterized as "largely experimental."
The Centers for Disease Control and Prevention (CDC) estimates that the 2025-2026 flu season has resulted in at least 15 million illnesses, 180,000 hospitalizations, and 7,400 deaths. The dominant strain this season has been H3N2, a subclade K variant nicknamed the "super flu" for its severe symptoms and ability to evade vaccine efficacy. Approximately 154 million doses of the flu vaccine were administered during this season.