Leana Wen: Here’s what a measles outbreak looks like

Thought Leader: Leana Wen

February 25, 2025

Why the return of measles is a public health tragedy.

Thanks to successful vaccination campaigns, most Americans today have never experienced a measles outbreak. So when they see news that rural West Texas has recorded 90 cases within the past month, the largest spike in the state in nearly 30 years, they might not understand why it’s so alarming.

Here’s why: Measles is notoriously difficult to control. The virus is airborne and can linger in the air and on contaminated surfaces for up to two hours. It is so contagious that 9 out of 10 unvaccinated children who are in contact with an infected person will fall ill. This is why cases are expected to multiply in the coming weeks. An outbreak has already been declared in neighboring eastern New Mexico, where nine people have been diagnosed thus far.

The virus can also have devastating consequences, particularly in young children. That parents have to discover this the hard way when they have access to a safe and effective vaccine is a public health tragedy.

Before the measles vaccine was introduced in 1963, the disease was a fact of life. It sickened 3 million to 4 million Americans a year, and nearly every child was infected before age 15. The initial symptoms are similar to those of the flu: high fever, runny nose, cough and red, watery eyes. A few days later, tiny white spots appear inside the mouth, followed by a rash that starts on the face and spreads to the body, arms and legs.

Most measles patients will fully recover, but complications are common, affecting 3 in 10 who fall ill. About 1 in 5 unvaccinated people need hospitalization. As many as 1 in 20 children develop pneumonia, and about 1 in 1,000 end up with brain swelling that can lead to seizures, deafness and permanent disability. Between 1 and 3 of every 1,000 children infected will die.

Even those who appear to have recovered might not be out of the woods. Measles can wipe out the immune system’s memory of past illness, leaving people susceptible to other pathogens. It can also cause a rare but terrifying illness, subacute sclerosing panencephalitis, seven to 10 years after infection, especially among children who contract measles before age 2. Early symptoms include poor school performance and temper tantrums. In time, children develop uncontrollable jerking movements, speech and intellect deterioration, difficulty swallowing and blindness. There is no cure for this condition, which is nearly always fatal within three years.

In the United States, these horrific consequences have been relegated to the history books because of the measles, mumps and rubella vaccine. Two doses of the shot are 97 percent effective at preventing measles. The high effectiveness also means that it’s possible to reach herd immunity — when immunity levels are so high within a population that it becomes difficult for a pathogen to spread. For measles, that level is 95 percent or above. This was achieved 25 years ago, when the United States officially declared measles eliminated.

These hard-won gains have been slowly eroding. Nationally, vaccination coverage among kindergartners decreased from more than 95 percent during the 2019-2020 school year to less than 93 percent in 2023-2024.

Many pockets of the country have significantly lower vaccination rates. In Gaines County, Texas, where most recent measles cases are clustered, nearly 14 percent of K-12 students have opted out of at least one required vaccine. Health officials say the portion of unvaccinated people there is probably higher because of the area’s large, isolated Mennonite population, whose data are underrepresented in official statistics.

Thus far, 16 measles patients have been hospitalized in Texas. Across the border in New Mexico, state officials put out public notices that people could have been exposed to the virus in an elementary school, a grocery store, an emergency room, a pharmacy and a church. Public health leaders in both states are educating the public on measles symptoms and setting up immunization clinics to try to curb the spread.

Time will tell how many more people will become infected and fall seriously ill in this outbreak. What’s certain is that this outbreak will not be the last. At least 15 states have proposed legislation to loosen vaccine requirements. In Texas, lawmakers have already introduced more than 20 such bills this year. Robert F. Kennedy Jr., the newly confirmed health and human services secretary, refuses to disavow the debunked theory that MMR is linked to autism. And among the several thousand Department of Health and Human Services employees terminated in Elon Musk’s purge of government agencies are those tasked with disease investigation and outbreak response.

It’s been said that vaccines are a victim of their own success. Indeed, younger generations fail to appreciate the extraordinary benefit of vaccines because they have never seen the lethal illnesses that vaccines help avert. One can only hope that parents learn this lesson before more children are infected and suffer the consequences of measles and other vaccine-preventable diseases.

This article is from WWSg thought leader, Leana Wen.