For the first time in almost 80 years, U.S. service members will no longer be mandated to receive the annual influenza vaccine.

Defense Secretary Pete Hegseth announced the change on April 22, 2026. Citing medical autonomy and religious freedom, he described the requirement as “overly broad and not rational,” telling troops that “your body, your faith and your convictions are not negotiable.”

The flu shot requirement that Hegseth ended had been in place since 1945, with one brief pause in 1949. It was part of a tradition of military vaccine mandates nearly as old as the United States itself.

As an epidemiologist who studies vaccine-preventable diseases, I find the end of the flu mandate striking less for its immediate impact than for what it signals. For most of American history, military commanders took for granted that infectious disease could cost them a war, which is why vaccination was considered a matter of military readiness rather than personal choice.

A tradition that started with George Washington

The first American military vaccine mandate predates the Constitution. In the winter of 1777, Gen. George Washington ordered the mass inoculation of the Continental Army against smallpox.

His decision wasn’t ideological – it was strategic. The year before, a smallpox outbreak had torn through American troops outside Quebec, contributing to the collapse of the northern campaign. John Adams famously wrote to his wife, Abigail, that smallpox was killing 10 soldiers........

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