Kennedy downplays immunity from vaccination as measles outbreak grows

By Neha Mukherjee, CNN

(CNN) — Cases in the ongoing measles outbreak have risen to 258 across Texas, New Mexico and Oklahoma, and state health departments are urging more people to get the measles-mumps-rubella vaccine.

In an interview with Fox News that aired Tuesday, US Health and Human Services Secretary Robert F. Kennedy Jr. said that “people ought to be able to make that choice for themselves. And what we need to do is give them the best information and encourage them to vaccinate. The vaccine does stop the spread of the disease.”

But Kennedy also downplayed the safety of the vaccine and wrongly told Fox News’ Sean Hannity that measles outbreaks could be driven in part by people who have waning immunity from the vaccine.

“When you and I were kids, everybody got measles, and measles gave you … lifetime protection against measles infection. The vaccine doesn’t do that. The vaccine is effective for some people for life, but for many people, it wanes,” Kennedy told Hannity.

“Some years, we have hundreds of these outbreaks. … And, you know, part of that is that there are people who don’t vaccinate, but also the vaccine itself wanes. The vaccine wanes 4.5% per year,” he said.

But Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, says that if that were the case, measles wouldn’t have been declared eliminated in the US in 2000.

There’s some dispute among experts about how much protection may wane, if at all. However, they all agree that in most cases, the vaccine confers lifelong immunity against the virus.

The current outbreak “is absolutely being driven and started by unvaccinated individuals,” said Dr. Michael Mina, chief scientific officer of the telehealth company eMed and an expert in the epidemiology, immunology and spread of infectious disease.

Even those who may have waning immunity will not transmit large amounts of virus, he said.

Levels of antibodies created by the vaccine might decrease over time, but with a virus like measles, its longer incubation period gives the body’s immune memory cells more time to help fight the infection. This enables long-lasting immunity from vaccination, Offit explained.

Since measles was declared eliminated in the US, there have been an average of about 179 cases reported each year, many of them related to international travel. There have been an average of about eight outbreaks per year – ranging from 1 to 25 annually – and most years, at least 60% of all reported cases have been tied to outbreaks. But even the worst outbreaks typically stay under 50 cases.

This is only the fifth year since 2000 that an outbreak has led to more than 100 cases and only the third year with more than 200 cases. The others were 2014, with an outbreak tied to Disneyland, and 2019, when a nearly year-long outbreak in New York came within weeks of ending the nation’s elimination status.

Immunity without the risk

Some of Kennedy’s statements promoted natural immunity, acquired when someone gets measles, over vaccine induced immunity.

Two doses of the MMR vaccine are 97% effective against measles. People who were naturally infected with measles will also have immunity, but not without serious risks.

“The goal of a vaccine is to induce the immunity that is a consequence of natural infection without paying the price of natural infection,” Offit said.

The price of infection can be high: One in five unvaccinated people with measles will be hospitalized, 1 in 20 children with measles will develop pneumonia, and 1 in 1,000 children with measles will develop encephalitis or swelling of the brain.

One to three in 1,000 children who have measles will die from complications, according to the US Centers for Disease Control and Prevention. A school-age child who was not vaccinated is among the two deaths that have already been associated with the ongoing measles outbreak.

Another possible consequence of infection is “immune amnesia.” When the measles virus infects immune cells, it can erase the body’s memory of how to fight other infections.

“So if you want to take the natural immunity route … you’re destroying your previously existing immune memory and putting yourself at risk for every other infection that you could get. And so there is no world in which measles is good for the body, and there’s no world in which getting measles infection is better than getting a measles vaccine,” Mina said.

Kennedy also inaccurately said vaccine-induced immunity may not be passed through breast milk to nursing infants the way natural immunity is.

“He is wrong. Maternal antibody transfer is a key form of neonatal protection against infectious diseases,” said Dr. Lynn Yee, professor of obstetrics and gynecology at the Northwestern Feinberg School of Medicine. “Even when a mother had vaccination many years ago, antibodies still transfer.”

This is especially important because infants can get protection against the virus through antibodies from their mother in the first six months of life, when they are too young to be vaccinated, she said.

Adverse events from vaccine are rare

Kennedy also incorrectly described adverse events from the MMR vaccine, saying it “causes deaths every year. … It causes all the illnesses that measles itself causes: encephalitis and blindness, et cetera.”

Dr. Peter Hotez, co-director of the Texas Children’s Hospital Center for Vaccine Development and dean of the National School of Tropical Medicine at the Baylor College of Medicine, called this “disinformation.”

“The measles vaccine is incredibly safe,” he told CNN’s Jake Tapper. “This is what anti-vaccine activists do is, they play up and try to scare you with the very, very rare side effects and forget to tell you about the horrific effects of the illness.”

Measles infection can cause encephalitis and blindness, but only a handful of these kinds of illnesses related to vaccination have ever been reported.

A study in which the US Food and Drug Administration and the CDC reviewed reports from the Vaccine Adverse Events Reporting System, in addition to medical records, death certificates, and autopsy reports, did not find evidence to suggest “a causal relationship between the MMR vaccine and death.”

“The MMR vaccine is extremely safe. The most common side effects that people may get is the low-grade fever for a few days, and sometimes people can get this temporary rash It usually resolves within 24 to 48 hours. Those are by far the most common symptoms, and there are a few more that are much less common, but they are extremely rare,” said Dr. Vivek Cherian, a Chicago-based internal medicine doctor.

More serious side effects from vaccination are extremely rare, according to the CDC.

“All of those [common side effects] are signs that the vaccine is working and your immune system is mounting the responses it’s supposed to to gain memory to protect you later. But many folks are touting these as significant adverse events, and so I think that the devil is really in the details on this,” said Dr. Christina Johns, a pediatric emergency physician at PM Pediatrics in Annapolis, Maryland.

CNN’s Deidre McPhillips contributed to this report.

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