A major influenza outbreak has swept through a US Air Force training base in Texas, leaving more than 150 recruits sick and prompting authorities to reintroduce flu vaccinations for trainees just weeks after the military made the shots optional.
At least 159 recruits at Lackland Air Force Base in San Antonio have been affected by the outbreak, according to reports from the New York Times and ABC News.
The cases emerged shortly after Defense Secretary Pete Hegseth ended the long-standing requirement for military personnel to receive annual influenza vaccinations.
Announcing the change in April, Hegseth argued that service members should be allowed to make their own medical decisions.
“We’re seizing this moment to discard any absurd overreaching mandates that only weaken our war fighting capabilities,” said Hegseth in an April social media video. “In this case that includes the universal flu vaccine and the mandate behind it.”
“Your body, your faith and your convictions are not negotiable,” said Hegseth.
Following the policy shift, vaccination uptake among recruits reportedly fell. Air Force officials told the New York Times that only about 40 per cent of trainees chose to receive the flu shot after it became voluntary.
The outbreak has spread within a training environment where recruits spend most of their time in close contact with one another. Trainees at Lackland live in shared dormitories, eat together and participate in group activities, creating conditions that can allow respiratory illnesses to move quickly from one person to another.
Lackland operates within Joint Base San Antonio, one of the largest military installations in the United States with about 70,000 members. The facility is often referred to as Military City because of its large military population.
Data from the Centers for Disease Control and Prevention shows that about 46 per cent of adults received flu vaccinations during the 2025-26 influenza season.
The outbreak has also drawn attention following the death of a trainee at the base. Keon McDaniel died on June 16 after suffering what Air Force officials described as a medical emergency.
Authorities have not established whether the death is linked to the influenza cases. Investigations into the cause of death are ongoing.
As efforts to stop further infections continue, Air Force officials have directed recruits at Lackland to receive influenza vaccinations. The measure is part of a broader response aimed at limiting the spread of the virus within the training facility.
The Pentagon referred questions about the outbreak to the Air Force press office. No immediate response was provided regarding the situation or the containment measures being implemented at the base.