Longtime vaccine skeptic and U.S. secretary of health and human services Robert F. Kennedy, Jr., reportedly believes routine influenza vaccines may have triggered his spasmodic dysphonia—a neurological condition that affects the vocal cords and a person’s ability to speak. But the claim, made in a wide-ranging recent interview with USA Today, is unsupported by evidence, experts say.
Kennedy told the outlet that he stopped getting his annual flu shot in 2005. “[Spasmodic dystonia is] why my voice is so screwed up,” Kennedy said, describing the vaccine as a “potential culprit that I cannot rule out. I can’t prove it.”
The comments are “one more assault on vaccine confidence,” says Robert Hopkins, medical director of the National Foundation for Infectious Diseases. “We do not have any known linkage between flu vaccine and voice disorders like this.”
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The exact causes of spasmodic dysphonia are unclear; experts suspect different brain areas may be involved and that the condition may have a genetic component.
The Dystonia Medical Research Foundation, meanwhile, says that there is “no evidence” that vaccines cause the condition. “In contrast, preliminary research suggests certain vaccinations may actually be protective against certain forms of dystonia,” the organization states.
An analysis of several common flu vaccine brands by MedPage Today found that only one, FluLaval, has dysphonia listed as a potential side effect. That vaccine was approved for use in the U.S. in 2006, after Kennedy said he stopped getting the flu shot. The Department of Health and Human Services did not respond to a request for comment.
Listing dysphonia as a possible side effect of that vaccine, Hopkins says, “means that there was at least one voice disorder during clinical trials.” That doesn’t constitute proof that dysphonia is linked to the vaccine, he says.
Kennedy’s comments have come amid a particularly severe flu season in the U.S.: so far in the 2025–2026 season, the U.S. Centers for Disease Control and Prevention estimates that the virus has caused at least 18 million illnesses and 9,300 deaths, including at least 32 children. According to the CDC, an estimated 90 percent of vaccine-eligible children who died of flu this season were not fully vaccinated.
Flu vaccines, like most medications, can cause side effects, but many have been in use for decades and are safely administered to millions of people every year. “The body of scientific evidence overwhelmingly supports their safety,” the CDC states.
“Flu vaccines are our best tool to reduce everyone’s likelihood of ending up with a severe flu or complications from the flu,” Hopkins says.