An endorsement of the measles, mumps and rubella vaccine by Health and Human Services Secretary Robert F. Kennedy Jr. has provoked an angry outcry from anti-vaccine activists.
"The most effective way to prevent the spread of measles is the MMR vaccine," Kennedy said in the third paragraph of a lengthy post on the social media platform X. Kennedy made the post following meetings on Sunday in Gaines County, Texas with the families of two children who have died of measles during a recent outbreak in the state. He also said he had instructed the Centers for Disease Control and Prevention to "supply pharmacies and Texas run clinics with needed MMR vaccines," along with other medical supplies.
Kennedy's endorsement is in line with all available scientific evidence on the MMR vaccine. "A single dose is roughly 93% effective at preventing illness, and the second dose gets that up to 97%," says Dr. Paul Offit, director of the Vaccine Education Center at the Children's Hospital in Philadelphia. According to the Texas Department of State Health Services, just 10 of the 481 measles cases recorded as of April 4 were in partially or fully vaccinated individuals — that's around 2% of all overall cases. So far three unvaccinated people, the two children in Texas and an adult in New Mexico, have died from the disease.
"I'm delighted to hear what Secretary Kennedy has said about giving the vaccination," says Dr. Kathryn Edwards, a retired professor of pediatric infectious disease. Edwards said she'd hoped for an explicit endorsement of the vaccine much earlier in January but that "it's better late than never."
But Kennedy's suggestion that the vaccine was effective infuriated several members of the anti-vaccine community who responded on X to the statement.
I’m sorry, but we voted for challenging the medical establishment, not parroting it.
— Mary Talley Bowden MD (@MdBreathe) April 7, 2025
Anti-vaccine anger
"I'm sorry, but there is no defense for this poorly worded statement," wrote Dr. Sherri Tenpenny, a prominent anti-vaccine activist who once claimed during a legislative hearing in Ohio that the COVID vaccine could cause patients to become magnetized, allowing them to stick "spoons and forks" all over their bodies.
Del Bigtree, a prominent anti-vaccine activist who supported Kennedy's presidential run and recently co-founded a non-profit with him called MAHA Action, also questioned the health secretary's endorsement. Bigtree suggested that Kennedy's post had "got cut off." He then went on to make unproven claims about vaccines and autism, and linked to a documentary he had made on the topic.
"We voted for challenging the medical establishment, not endorsing it," posted Dr. Mary Talley Bowden, a Texas-based physician who has opposed COVID vaccines and is currently fighting a complaint from Texas's medical board over hospital admitting privileges. Bowden says the complaint is related to her prescribing patients ivermectin. Ivermectin is an unproven alternative therapy for COVID.
"Kennedy was one of those candidates that attracted people who might not vote for Trump," Bowden told NPR in an interview. Much of the attraction was from people who were "very fed up with what happened during the pandemic," she says. "Neither Biden or Trump were willing to even talk about the pandemic, and Kennedy was," she says.
She says that Kennedy's decision to endorse the MMR vaccine to control the outbreak reminds her of the heavy-handed response to COVID.
"Do we need to make a proclamation, 'Ok, this is what needs to be done'?" she says. "That's what rubs me the wrong way."
Kennedy's statement also contradicts years of his own vaccine skepticism. The health secretary formerly chaired an anti-vaccine non-profit called Children's Health Defense that, during a measles outbreak in 2019, tried to sue New York over the state's school vaccine requirement. It ultimately lost the case.
In 2023, during an interview with the popular podcaster Joe Rogan, Kennedy denied that the measles vaccine had led to a drop in deaths. He claimed that malnutrition was the root cause of measles deaths, and that by the time the vaccine debuted in 1963, mortality was already low. The few deaths that did occur "were all kids in the Mississippi Delta, black kids, severely malnourished, and they were dying of measles," he told Rogan. Kennedy did not cite any evidence for that claim.
In his new role, the health secretary has occasionally acknowledged the efficacy of the MMR shot. "Vaccines not only protect individual children from measles, but also contribute to community immunity, protecting those who are unable to be vaccinated due to medical reasons," he wrote in an op-ed on Fox News on March 2. But in the same post, Kennedy claimed vitamin A can "dramatically reduce measles mortality." Offit says vitamin A does not affect the disease course in developed nations like the United States, and that it can damage children's livers in large doses. Texas Public Media reported that several children in West Texas were hospitalized with vitamin A toxicity following his Fox News statement.
Alternative Therapies
It was unclear why Kennedy chose this moment to explicitly endorse the MMR shot. The Department of Health and Human Services did not immediately respond to NPR's request for a comment. In a second post later Sunday evening, Kennedy posted pictures posing with the families of those who had lost children, and promoted two therapies, "aerosolized budesonide and clarithromycin."
Budesonide is an inhaled steroid used to treat asthma and has "no role in measles," Offit says. Clarithromycin is an oral antibiotic, but Offit says it's the wrong kind of antibiotic for treating secondary bacterial infections caused by measles. "Both of those things are valueless," he says.
Offit says that, despite Kennedy's online endorsement, he expects the measles outbreak to continue and possibly worsen. "This is a massive outbreak that is not being controlled," Offit says. Measles was eliminated in the U.S. in 2000, but it is killing children again. "I have never been more upset; it's just so hard to watch this."
NPR's Selena Simons-Duffin and Rob Stein contributed to this report.
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