When Robert F. Kennedy Jr. was confirmed as America’s secretary of health and human services, neutral observers might have asked themselves: Would it be possible for a lawyer who had questioned the safety of childhood vaccinations for two decades to look at the available data and reconsider his views?
Kennedy’s recent interviews with Fox News, along with an op-ed he published on that outlet’s website, have been enough to make many experts conclude the answer is “no.”
Parsing every claim about the measles vaccine that Kennedy has made would take a long time, so let’s focus on one: that the vaccine causes deaths every year. Researchers say that simply isn’t true, except potentially in a small number of people who are not supposed to receive it — those with compromised immune systems.
“There are adverse events from the vaccine,” Kennedy said in a March 11 interview with Fox’s Sean Hannity. “It does cause deaths every year. It causes — it causes all the illnesses that measles itself causes, encephalitis and blindness, et cetera. And so people ought to be able to make that choice for themselves.”
The Infectious Disease Society of America says there have been “no deaths related to the measles, mumps and rubella vaccine in healthy individuals.” (Since the 1970s, the measles vaccine has been given in a combination shot with mumps and rubella to minimize the number of injections kids get.)
“The MMR vaccine has never been found to cause a death in an immunocompetent individual,” Daniel Griffin, chief of the division of infectious diseases at Island Infectious Disease Medical in New York said, echoing that conclusion. “If you’ve got someone who has a compromised immune system, and someone doesn’t know any better and gives them an active vaccine, which is what you are not supposed to do, then, you know, that could result in a death.”
Measles is itself a killer. Before the measles vaccine was introduced in 1963, it was a near-certainty that children would be infected before the age of 15 — about three or four million cases occurred every year. Most children had no complications, but a little more than 1 in 1,000 would die after developing pneumonia or encephalitis. That equates to 400 or 500 deaths a year.
A 2024 study in the The Lancet estimated that measles vaccines prevented 93.7 million deaths globally between 1974 and 2024 — a number equivalent to a quarter of the U.S. population.
Measles isn’t a huge threat now. Public health experts worry that won’t remain the case because of low vaccination rates. Importantly, even though the measles vaccine is one of the most effective on the market, it will not protect every person vaccinated. Perhaps one person in 20, maybe less, will not have fully protective antibody levels. Having more unvaccinated people means more risk for everyone, including people with compromised immune systems and children too young to receive the shot. (Children are eligible for the shot at 1 year of age.)
All medical products come with risks. The measles vaccine includes a weakened virus, which means that scientists developed it by passing a measles virus through cell cultures and chicken embryos until it became less able to cause serious symptoms in people, but still able to spur immunity. It is, essentially, measles with dramatically less risk.
The shot still commonly causes a fever. Seizures caused by fever occur in 3 in 10,000 people who receive the shot. Clotting issues occur in roughly 3 in 100,000. Allergic reactions occur in perhaps 3 in a million.
Other side effects are even rarer than that. As Kennedy noted, the vaccine can cause encephalitis, although case counts appear vanishingly rare. There are also scattered case reports of patients developing optic neuritis, a condition that can cause blindness, but in most of these patients sight returned with time or treatment. Those cases are so rare it is difficult to even estimate the risk of them occurring — except to say that it is very, very low.
Kennedy’s assertion that the vaccine causes deaths every year likely comes from reports to the Vaccine Adverse Event Reporting System (VAERS), a government-run database that allows individuals or their doctors to submit reports of bad outcomes they think were caused by a vaccine. It is an important early warning system for vaccine side effects, but a flawed one, because there is no way of controlling for the fact that people sometimes think a bad outcome may have been caused by a vaccine when it was not. When there is press coverage of vaccines, reports of side effects tend to go up even though the number of children receiving the vaccines do not.
In the mid-1990s, the Institute of Medicine — now known as the National Academy of Medicine — did a careful review of reports from VAERS. They concluded that except for allergic reactions and blood clot disorders, which were incredibly rare, there was no link between the MMR and deaths.
Kennedy’s claim about vaccine deaths came amid a series of other claims about vaccine safety. In one interview, he claimed vaccines are rarely compared with placebos; they usually are. He also made it sound as if measles immunity from the vaccine wanes faster than it does; in fact it is typically lifelong.
If, as Kennedy acknowledged, everyone will either get the vaccine or measles, it would seem advisable to get the vaccine, which clearly results in few if any deaths, instead of measles itself, which we know is capable of causing hundreds of deaths.
People should be able to make their own decisions about their children’s vaccinations. But, as Kennedy says, they should have accurate scientific information.
A spokesperson for the Department of Health and Human Services did not return a request for comment.