The U.S. military is racing to vaccinate new recruits against influenza after a two-month halt on mandatory shots, but the vaccines now being deployed across basic training camps expire June 30 and replacement doses will not arrive for at least two months, leaving officials to rely on other containment measures to control a growing outbreak at a Texas Air Force base.
The Air Force, Army, and Navy reinstated flu shot requirements for recruits this week after Defense Secretary Pete Hegseth ended the mandate for all troops in April, citing medical autonomy and religious freedom for service members. Military leaders have reportedly been working for weeks to reestablish the vaccine requirement, even before the outbreak at Lackland Air Force Base in San Antonio, Texas, sickened at least 275 people and hospitalized four. One recruit, Keon McDaniel, died earlier this month after experiencing a medical emergency; his death remains under investigation, and officials said it is not yet clear whether it is linked to the flu outbreak.
When Hegseth announced the mandate would end, he said services could ask for exceptions allowing them to keep the vaccine mandatory. The decisions to re-implement the requirement are part of that process, a Pentagon official said.
The narrow window for vaccination stems from the seasonal nature of flu vaccine production. Toti Sanchez, the former deputy chief at the armed forces health surveillance division of the U.S. Defense Health Agency, said the earliest the next season’s doses have historically been available is late August or early September.
“You just can’t change that. The manufacturing timeline is basically etched in stone,” Sanchez told The Guardian.
It is possible the military will extend use of the current vaccines beyond their June 30 expiration date, but Sanchez said that is “unlikely.” He noted that manufacturers typically shift production to the next season’s formulation at this time of year, making stock low.
Once the vaccine supply runs out, officials are expected to turn to other infection-control practices: splitting recruits into smaller groups for eating and showering, emphasizing handwashing and sanitizer, and potentially using face masks or respirators, though Sanchez said masks are difficult to train in and recruits cannot sleep or shower in them.
About 700 new recruits arrive at Lackland — the only Air Force basic training site — every week. After the mandate was lifted, only about 40% of trainees opted to receive the shot, according to a source familiar with the situation.
Caitlin Rivers, a senior scholar at the Johns Hopkins Center for Health Security and a former civilian epidemiologist for the Army, described basic training as a “very vulnerable environment” for the spread of infectious disease. Recruits live in crowded quarters and are pushed to their physical limits under high stress with little sleep, she said. Younger people in their late teens and early 20s are particularly susceptible to influenza because they have not encountered many variants of the virus.
“Basic training is a unique environment,” Rivers said. “The flu vaccine is critical to preventing outbreaks and maintaining readiness.”
The Army is also planning to mandate vaccines for troops deploying overseas, first responders, child care workers, healthcare personnel, prison staff, and soldiers in large-scale training exercises.
Rivers said the current situation reflects a pattern of “panic and neglect” that has led military leaders to forgo vaccinations and then ramp them up, often at great expense, when outbreaks inevitably occur.
Sanchez, who said the flu vaccine mandate was first implemented in 1945, described the policy reversal as returning to a problem the military solved eight decades ago.
“Here we are, 81 years later, and we’re turning back the clock,” Sanchez said. He said the episode points to the potential benefit of mRNA flu vaccines, which could be updated more quickly than traditional shots. Moderna is seeking U.S. Food and Drug Administration approval for the first mRNA flu vaccine for people 50 and older. Sanchez said such a platform could allow production of an updated influenza vaccine within one to two months instead of five to six.