The U.S. military will no longer require service members to get an annual flu shot according to a post Tuesday by Defense Secretary Pete Hegseth on the social media platform X.
Hegseth said the mandatory flu vaccine requirement has been discarded “effective immediately.”
“The War Department is once again restoring freedom to our Joint Force,” the secretary wrote.
The flu vaccine has been required annually for U.S. military personnel since the 1950s to preserve the health of the force, and generally, the Defense Department has aimed to inoculate more than 90% of active-duty personnel.
The program has been a major factor in lower rates of hospitalizations among service members than national U.S. rates, according to an October 2025 Armed Forces Health Surveillance Division report.
According to the report, the annual flu vaccine has shown effective in preventing the impact of flu on older service members and is important for protecting the health of the force, particularly in close quarters at recruit stations, which have the highest rates of flu infections each year across the services.
The incidence rate of hospitalizations for flu among recruits from 2010 to 2014 was 70 per 100,000 compared with the overall military rate of 7.4 per 100,000 according to the report.
“The higher burden of hospitalization among recruits offers DOD vaccine distribution priority considerations in the future,” wrote the report authors.
But last year, the Centers for Disease Control and Prevention under the Trump administration dropped recommendations that children receive the annual flu shot, and a recent judge’s ruling on recent recommendations for adults has left that recommendation in limbo.
The CDC estimates that 26 million Americans contracted flu from Oct. 1, 2025, through Feb. 28, with 340,000 hospitalizations and 21,000 deaths, including 139 children. The CDC estimated that the flu vaccine prevented 180,000 hospitalizations and 12,000 deaths.
There are several variations of the influenza virus and each season is affected by different strains. Mutations of the virus can be deadly, as demonstrated in 1918 when a strain known as the Spanish Flu infected more than a quarter of the world’s population, or 500 million people, and killed 50 million, including 675,000 Americans.
This year’s vaccine was not considered an effective match, with preliminary dating showing it 25% to 30% effective in preventing adults from needing to see a doctor. Generally, the vaccine is considered effective if it keeps 40% to 60% of ill adults from medical treatment.
More than 45,000 U.S. service members died from the virus, which some medical historians think may have been spread by troops deploying to fight in World War I.
In early 2023, the Defense Department dropped a mandate for service members to get the vaccine for COVID-19 as a result of a law passed by Congress in 2022. Previously, more than 8,400 service members left the military rather than get the vaccine, with most citing health concerns or religious reasons.
COVID-19 infected nearly 453,000 troops and killed 96, according to the Defense Department.
Of those service members who received the vaccine, 25 developed a rare side effect, myocarditis, or inflammation of the heart muscles. Myocarditis also is a side effect of the COVID-19 virus, affecting roughly 20 out of every 100,000 infected persons.
The Pentagon vaccinated more than 2 million service members from December 2020 through December 2022.
In a release Tuesday, Hegseth said the flu vaccine requirement was “just overly broad and not rational.”
“If you, an American warrior entrusted to defend this nation, believe that the flu vaccine is in your best interest, then you are free to take it; you should. But we will not force you,” Hegseth said in a statement.
Patricia Kime is a senior writer covering military and veterans health care, medicine and personnel issues.