Maryland reported 3 measles cases in March. Here’s what you need to know.

Maryland health officials confirmed three measles cases in Maryland this month, making the state one of 18 with reports of the disease in 2025. 

In Maryland, the first measles case this year was confirmed by state health officials on March 9 from a Howard County resident who traveled internationally. The other two — confirmed March 20 — stemmed from two Prince George’s County residents who also traveled internationally, but were unrelated to the first case. 

All three cases were connected to Washington Dulles International airport, according to the state health department. They were unrelated to the bigger outbreaks from around the country, officials said. 

Here’s what we know. 

Measles is an airborne, highly contagious disease. Up to nine out of 10 people in close contact with a measles patient will develop the virus, according to the CDC. 

There have been 378 measles cases in the U.S. this year across 18 states. Of those cases, 95% of affected people were unvaccinated or had an unknown vaccination status, according to CDC data. 

A majority of the cases stem from outbreaks in Texas and New Mexico earlier this year. The CDC has confirmed two deaths — a school-aged child in Texas and an unvaccinated adult in New Mexico.

Most U.S. cases are among 5 to 19-year-olds, but a majority of hospitalizations have been people under 5. The disease can be more dangerous for children because they don’t receive a full dose of the measles, mumps and rubella vaccine until they’re 6, said Amesh Adalja, a senior scholar at Johns Hopkins University who studies infectious diseases. 

“On a global scale, in the last year over 100,000 people died of measles primarily in resource poor countries,” Adalja said. “Even if it doesn’t have death … it also has the ability to impair your immune function after an infection.”

The measles, mumps and rubella vaccine, or MMR, was first licensed for public use in 1963 and an improved version distributed in 1968. After widespread vaccination efforts, the World Health Organization declared the disease eliminated in 2000. 

In 2019, more than 1,200 people were infected with measles, marking the largest outbreak since 1992 that threatened the country’s elimination status. 

Public health experts warn increased vaccine hesitancy may put people at risk for preventable diseases, including measles. People who are vaccinated can still get the disease, but it’s extremely rare, Adalja said. 

“When you see these measles outbreaks occurring in places like the United States, this is all by choice,” he said. “This is all preventable.” 

Mika Hamer, an assistant public health professor at the University of Maryland, said that because vaccinations are never completely risk free, fears about side effects can spread among communities. 

“Vaccine hesitancy comes from a place of fear or concern and of not wanting to do something if you don’t feel confident in what the outcomes will be,” Hamer said. “[But] they’re very well studied, and overwhelmingly, the benefits of vaccination outweighs the individual risk.”

A critically flawed study — which was later retracted — in the late 1990s claiming that MMR vaccines cause autism received high public attention and caused rumors to proliferate, Hamer said.

Maryland has consistently had one of the highest MMR vaccination rates out of all U.S. states and has remained above the national average, according to CDC data. 

A 95% or higher vaccination rate is considered herd immunity for measles, which protects people who can’t get vaccinated such as infants or those with allergic reactions, according to WHO. Measles has a higher threshold than other preventable diseases — such as polio’s 80% herd immunity indicator — because it’s extremely contagious, according to the NIH. 

“Herd immunity is the way that you make a community resilient to the virus,” Adalja. “When herd immunity slips below that threshold, it becomes easier and easier for a virus as contagious as measles to find people.” 

Celebrating public health wins and increasing access to public health information are key steps that can increase vaccination rates, Hamer said. It’s important to combat misinformation, especially online, to ensure public health safety, she said. 

“We don’t have to abandon strategies that we have and that we know work to prevent illness,” Hamer said. “To me, it’s a failure of our healthcare system, our public health system and really us as a country that in 2025 a child would die from a vaccine-preventable illness.”