Health officials grapple with ongoing measles jump

A spate of measles outbreaks across the country represents an early challenge for Health and Human Services Secretary Robert F. Kennedy Jr., who took office in February. The number of confirmed cases of measles has risen to above 700, according to data from the Centers for Disease Control and Prevention. The highly contagious disease has spread to 25 states, and the CDC says it has caused three deaths.

In 2000, the World Health Organization declared measles was eliminated in the United States, meaning there had been no continuous spread of the disease within the country for 12 months. But CDC numbers show that the number of children who do not receive the measles, mumps, rubella (MMR) vaccine has risen slightly, with some parents choosing to opt out over health or pro-life concerns.

Measles is highly contagious, and an infected individual can spread the virus before they experience symptoms, which typically include a cough, runny nose, and fever, followed by a distinctive red rash. A large majority of people who catch measles will recover within two weeks. One in 1,000 children with measles will develop encephalitis, which is an infection of the lining of the brain that can lead to permanent deafness or other complications. According to data from the CDC, 1 to 3 in 1,000 children who catch measles will die.

Travelers arriving from abroad regularly bring measles into the country. But Mike Jackson, an associate professor of biology at Patrick Henry College, explained that people who contract measles overseas usually do not cause an outbreak in the United States.

“Most of the people around them are vaccinated, so it doesn’t really go anywhere,” he said. Sometimes an infected person “winds up having an encounter with someone from a population that doesn’t have much pre-existing immunity.” This can lead to a dramatic spike in cases.

The current outbreak has seen the deaths of two Texas girls and one New Mexico adult, none of whom had received a measles vaccine. Both girls were part of a Mennonite community in Gaines County that has a vaccination rate lower than the national average. The father of one of the children, 8-year-old Daisy Hildebrand, denies that she died from measles. He said she had several other conditions, including hospital-acquired pneumonia, and received “foolish” care from doctors.

Over the past two decades, the United States has had very low numbers of confirmed cases of measles. Some years, there were fewer than 100. The year 2019 was an outlier with 1,274 confirmed cases. That outbreak most significantly affected Orthodox Jewish communities in New York. There were no confirmed deaths from measles that year.

“What measles will do is find those individuals and those pockets where immunization rates are low,” said Dr. Gregory Poland, president of the Atria Academy of Science and Medicine in New York. He is quick to disclose that he provides advice to nearly every vaccine manufacturer, including the two that make MMR vaccine.

To avoid catching measles, the CDC recommends 2 doses of the MMR vaccine, with the first dose administered at ages 12-15 months and a second dose at 4-6 years of age.

“If you got one dose of vaccine, there’s about a 93% chance or so that you’re immune. If you got two doses, there’s about a 97-ish% chance that you are immune,” said Poland. “There is a lot of nuance and complexity in this. If you got it and you were immunocompromised, those numbers are even lower.” He added that the numbers drop even further for recipients of bone marrow or organ transplants and patients taking immunocompromising medication, and he said that some people who received vaccine versions that were discontinued in the mid-1970s might need to be reimmunized.

During the 2023-24 school year, the percentage of kindergartners with an exemption for one or more vaccines rose to 3.3% from 3.0% the year prior, according to the CDC. During that same school year, 92.7% of kindergartners had the MMR vaccine. A decade prior, that figure was 94%.

However, Poland argued that this data can be misleading when evaluating the threat of measles. “First, we have zero idea of the immunization rates of the substantial number of people who are undocumented, which is a higher number than it was a decade ago,” he said. “No. 2, mobility continues to increase, so the risk of imported disease continues to rise. No. 3, probably the most important, is that you achieve herd immunity right around 95% so the farther this falls below 95% the riskier and riskier it gets.” He also adds that a national average can mask large disparities between local areas.

Poland calls the current outbreak “the canary in the coal mine” for falling MMR immunization rates.

Some pro-life parents have a moral objection to the MMR vaccine. Researchers tested or developed this vaccine and some others using cell lines derived from fetal tissue obtained from elective abortions that happened decades ago.

Other parents opt their children out of the MMR vaccine because they believe the disproven theory that it causes autism. Jackson said this idea dates back to a 1998 study published in a medical journal by a former British doctor named Andrew Wakefield, linking the MMR vaccine to autism. “The part of the story you don’t hear is that that study was progressively shown to be both, first scientifically very flawed and then, actually fraudulent,” he said. “He sort of manufactured data, and it’s been withdrawn by the journal.”

Jackson said that “really rigorous” studies have since looked into the theory, but “they haven’t been able to find any connection between the MMR vaccine and risks of autism.”

On April 16, HHS Secretary Kennedy held a news conference to discuss a CDC finding that 1 in 36 children, and 1 in 20 boys, has autism. Kennedy called autism an “epidemic” and disputed the notion that it is not more prevalent today than in the past—only more diagnosed. “Year by year, there is a steady, relentless increase,” he said.

Kennedy said he will soon announce a series of studies to identify causes of autism, and he vowed to identify the environmental toxin he believes is causing autism. “Somebody made a profit by putting that environmental toxin into our air, our water, our medicines, our food,” he said. “It’s to their benefit to say, ‘Oh, this is all normal. It’s always been here.”

Earlier in April, Kennedy traveled to Texas to attend Daisy Hildebrand’s funeral. In a lengthy post on the social media platform X on April 6, he detailed the ways HHS is supporting local health officials to manage the outbreak. He also stated that “the most effective way to prevent the spread of measles is the MMR vaccine.”

Kennedy’s strong endorsement of the vaccine surprised some, since he has frequently questioned vaccine safety in the past. In an interview on The Joe Rogan Experience podcast in 2023, Kennedy said that rates of measles infection had already decreased significantly before the introduction of the vaccine in the 1960s. He said those still dying “were all kids. Most of them were kids in the Mississippi Delta, black kids, severely malnourished, and they were dying of measles. And this was before the war on poverty … it’s hard for a disease to kill a healthy person.”

There are some small risks associated with the MMR vaccine. Around 1 in 3,000-4,000 children who get the MMR vaccine will have febrile seizures. “It doesn’t put you at higher risk for more seizures in the future,” said Jackson. “But it’s certainly a scary experience for parents who are going to wind up with an ER visit for the child.”

More rarely, the vaccine can cause immune thrombocytopenic purpura. Studies suggest 1 in 100,000 to 1 in 250,000 doses of the MMR vaccine may result in the clotting disorder, which is temporary but does require medical care.

The risk of an adverse reaction to the MMR vaccine is much lower than the risk of a serious health problem or death from measles.

Jackson thinks the current outbreak will probably end like the one in 2019. “Overall, vaccine coverage is still fairly high,” he said. “So we won’t see rates as high as in previous decades.” But he added a word of warning: “It’s not over yet by any means.”