Measles cases are surging in West Texas, where an outbreak has led to the first U.S. death from the virus in a decade.
But in a meeting with President Trump and other cabinet officials this week, the health secretary, Robert F. Kennedy Jr., said the situation was “not unusual.”
“We have measles outbreaks every year,” he added. Mr. Kennedy has also said in the past that immunizations against measles and some other infectious diseases are unnecessary and risky.
Public health experts said that while it’s true we do have measles cases in the United States every year, the latest outbreak is concerning because of its size, because a child has died and because larger outbreaks like this are becoming more frequent as vaccination rates decline.
“While we certainly see measles cases from time to time, it’s a rarity that we see an unfolding outbreak of this scale,” said Jason Schwartz, an associate professor of health policy at the Yale School of Public Health. At least 164 people have been sickened with measles so far this year. That is more than half the number of cases in all of 2024, and higher than the 59 cases documented in 2023.
How ‘normal’ are measles outbreaks?
Measles was declared eliminated from the U.S. in 2000, which was considered a landmark public health achievement made possible by the vaccine. Since then, there have been cases every year — typically originating with somebody who traveled abroad to a destination where measles is more common, and brought the virus back.
But in the first decade after elimination, the virus didn’t spread beyond a small number of people, experts said, because most people in a given community were vaccinated. That has changed, however, in recent years. In the 2023-24 school year, 39 states had measles vaccination rates below 95 percent, the target rate to achieve the “herd immunity” that can stem the spread of the virus. That’s up from 28 states during the 2019-20 school year, according to KFF, a nonprofit health policy research group.
Lower vaccination rates have made it possible for larger outbreaks to occur more easily. That was the case in Southern California in 2014 and 2015, when an outbreak linked to Disneyland grew to about 150 cases, and in New York in 2018 and 2019, when more than 600 cases emerged in New York City and another 300 in Rockland County.
“That is becoming, unfortunately, a more common reality in the United States because of decreased vaccination rates of our population,” said Dr. Lori Handy, an associate director of the Vaccine Education Center at the Children’s Hospital of Philadelphia.
How effective is vaccination? And how safe?
A single dose of the measles vaccine, which is delivered as part of a combination measles, mumps and rubella vaccine known as M.M.R., is 93 percent effective against measles. The U.S. childhood vaccine schedule recommends two doses, which together are 97 percent effective.
Some fully vaccinated people (3 in 100) can still develop measles if they are exposed to the virus. But their symptoms are generally much milder, said Angela Rasmussen, a virologist with the University of Saskatchewan. Some people believe that means the vaccine doesn’t work, she added, but that is not true.
“It keeps you out of the hospital and keeps you out of the morgue,” she said. “That’s what the measles vaccine does.”
The measles vaccine has been a particular target of vaccine skepticism because of now-debunked research linking it to autism. But the vaccine has proved to be extremely safe and highly effective over more than 60 years of use and studies of tens of thousands of children, said Dr. Adam Ratner, a pediatric infectious diseases expert in New York and the author of a book on measles.
Is the spread of the virus inevitable?
Measles is an extremely contagious virus. It lingers in the air or on surfaces for hours after an infected person leaves a room. And it is still much more common in other parts of the globe.
“That creates the environment, that creates the kindling,” Dr. Schwartz said. But it doesn’t mean that large outbreaks or the wide spread of measles is unavoidable in the United States.
“The fuel is unvaccinated individuals,” he said.
In Gaines County, Texas, where the current outbreak is centered, the vaccination rate among kindergartners is 82 percent. (Because school-age children are the focus of community vaccination efforts, vaccination rates among kindergartners give an approximate sense of community rates, Dr. Schwartz said.) Nationwide, the M.M.R. vaccination rate is just under 93 percent.
With vaccination rates falling, Dr. Ratner said, “I think we’re going to have a lot more Gaines Counties.”
How serious is a case of measles?
Before 1963, when the first measles vaccine was licensed, measles infected three million to four million people a year and was responsible for nearly 50,000 hospitalizations and 400 to 500 deaths annually in the United States, according to the Centers for Disease Control and Prevention.
“The risk of measles infection sometimes gets overlooked with the passage of time and how far most Americans are from seeing measles,” Dr. Schwartz said.
Measles typically begins with a fever, cough, runny nose and watery eyes, as well as a rash that usually first appears on the face and then spreads downward.
About 20 percent of unvaccinated people who are infected are hospitalized, according to the C.D.C. Complications are more common among pregnant women, those with weakened immune systems and babies and young children, whose immune systems are still developing.
“This is not a run-of-the-mill common cold,” Dr. Handy said.
As many as one out of every 20 children infected with measles will develop pneumonia, according to the C.D.C. One out of every 1,000 children get brain swelling, which can lead to blindness, deafness or seizures. In extremely rare cases, Dr. Ratner said, measles can also cause a progressive and fatal neurological disease that develops several years after an infection.
And one to three out of every 1,000 children infected with measles will die.
Today, measles still kills an estimated 100,000 people — most of them children — around the world each year.
Dr. Handy, who has young children, said measles is concerning to her both as a doctor and a parent.
“I know what to worry about,” she said. “And measles terrifies me.”
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