The Trump administration’s new order to end the mandatory vaccination of military personnel against the flu is cutting a tradition that originated in the days of George Washington.
For the first time in nearly 80 years, the U.S. military has will not be required to receive the vaccine annual against the flu.
The Secretary of Defense, Pete Hegsethannounced the change on April 22, 2026. Citing medical autonomy and religious freedom, he described the requirement as “overly broad and irrational”, telling the troops that “your body, your faith and your convictions are not negotiable”.
The flu vaccine requirement, which Hegseth ended, had been in effect since 1945, with a brief pause in 1949. It was part of a tradition of mandatory military vaccination almost as old as the United States itself.
The end of the mandatory flu vaccine is impactful less because of its immediate effect than because of what it signals. For most of American history, military commanders assumed that infectious diseases could cost them a warwhich is why vaccination was seen as a matter of military readiness rather than personal choice.
A tradition that began with George Washington
The first American military mandate for vaccination predates the Constitution. In the winter of 1777, General George Washington ordered the mass inoculation of the Continental Army against smallpox.
Your decision It wasn’t ideological.but strategic. The previous year, a smallpox outbreak had decimated U.S. troops on the outskirts of Quebec, contributing to the collapse of the campaign in the north. John Adams wrote to his wife, Abigail, that smallpox killed 10 soldiers for every one who fell in battle.
A inoculation in 1777 was risky. The procedure, called variolation, involved deliberately infecting a soldier with a small amount of the smallpox virus to develop immunity. Washington gambled that losing a few soldiers to inoculation was better than losing a war to the virus. Historians credit this decision with saving the Continental Army.
This pattern continued for centuries: when an infectious disease threatened to remove more soldiers from the front line than enemy fire, the soldiers needed protection.
American troops received smallpox vaccinations from the War of 1812 through World War II. During World War I, the Army added typhoid vaccination. During World War II, expanded vaccination requirements to also include tetanus, cholera, diphtheria, plague, yellow fever and, in 1945, influenza.
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The mandatory flu vaccine arose from military experiences during the 1918 flu pandemic. That spring, a new strain of flu spread through overcrowded Army training camps and traveled to Europe with American troops. About 45,000 US soldiers died of influenza during the First World War – almost the same number as the approximately 53,000 killed in combat.
The 1918 pandemic made it clear that a respiratory virus could paralyze an army. In 1941, as the country prepared to enter another world war, the U.S. Army organized a flu committee that partnered with the University of Michigan to develop the first flu vaccine. Clinical trials on military recruits showed that the vaccine reduced the incidence of influenza by 85%, and in 1945 the Armed Forces made vaccination mandatory. Approximately 7 million military personnel were vaccinated this year.
The requirement was briefly lifted in 1949, after scientists realized that the vaccine needed regular updates due to virus mutations. Once the formulations could be adjusted seasonally, the mandate returned in the early 1950s and remained in force continuously – until Hegseth’s policy change.
COVID-19 changed vaccination policy
For decades, mandatory vaccination was a common fact in military life, but COVID-19 changed that.
In August 2021, all soldiers were ordered to be vaccinated against COVID-19. More than 98% of active military personnel complied with the orderbut the requirement has become a point of conflict. More than 8000 military personnel have been involuntarily discharged for refusing to take the vaccine.
In 2023, Congress passed a law that required the Pentagon repeal the mandatory vaccination against COVID-19 in the Armed Forces. This repeal reshaped the policy around mandatory military vaccinations. In January 2025, President Donald Trump ordered the reinstatement, with retroactive pay, of military personnel discharged for refusing to take the COVID-19 vaccine.
When announcing the end of mandatory flu vaccinations, Hegseth relied heavily on the language of “medical freedom”which emerged from the debate over the COVID-19 vaccine, rather than being based on new evidence about the flu or the vaccine’s effectiveness.
The medical freedom movement opposes government intervention in what its advocates consider personal health decisions – including public health recommendations such as mandatory vaccination, use of masks and social distancing.
Is the justification for vaccination still valid?
Critics of mandatory flu vaccination in the Armed Forces argued that the flu represents a lesser threat than in 1918that the military is healthier than the general population, and that personal choice should prevail over public health rationale for a seasonal virus.
Epidemiology tells a different story. Although flu seasons can vary in severity of illness, the virus mutates so unpredictably that pandemic flu seasons – such as those in 1918, 1957, 1968 and 2009 – are a recurring possibility. The flu still hospitalizes and kills tens of thousands of Americans annually. The Centers for Disease Control and Prevention estimates that the flu vaccine prevented approximately 180,000 hospitalizations and 12,000 deaths during the 2024-2025 season.
The armed forces operate precisely in the conditions that favor the spread of respiratory viruses: recruit training centers, barracks, ships and submarines, where people live in close proximity.
The logic that led Washington in 1777 and the Army surgeon general in 1945 to require vaccination has not changed much. A sick soldier cannot be mobilizedcannot train and can spread the disease throughout the unit.
What has changed is the political weight attributed to individual refusal – and this, more than the biology of the flu or the effectiveness of the vaccine, is what the end of this mandate reflects.
