The growing number of measles cases in Texas leading to the first death in a decade is alarming public health experts in Maryland and elsewhere who are worried about the possibility of a nationwide spread.

Measles is so contagious, they say, that people can become infected by walking through the same space hours after an infected person coughed. One in five people may become hospitalized. Many patients suffer long-term complications.

In the measles outbreak in rural West Texas, where an unvaccinated child died this week, more than 120 cases have been reported.

The concern is now extending to Maryland, even though it’s among the states to reverse a slide in vaccinations since the coronavirus pandemic. Medical experts worry that vaccine hesitancy is on the rise, threatening progress and perhaps leaving pockets of susceptible children.

“People fear what is in front of them, and what they see is misinformation about the safety of the vaccine,” said Dr. Esther Liu, chair of pediatrics at the University of Maryland Baltimore Washington Medical Center.

“They get into the mindset of why risk it. There is no measles here,” Liu said.

She added since the Texas outbreak began last month, she has been getting more calls and questions from parents about vaccines, particularly the one for measles, mumps and rubella, known as the MMR vaccine.

Measles was considered eliminated in the United States in 2000, but cases persisted among people who had traveled to countries where it has been more prevalent.

All 50 states require school-age children to be vaccinated, with religious and medical exemptions in many states, including Maryland. But rates dropped during the pandemic below the 95% threshold. That’s the level considered necessary for the broad community protection known as herd immunity.

In Maryland, federal data show more than 96% of children received two doses of the vaccines against measles during the 2023-2024 school year, according to the U.S. Centers for Disease Control and Prevention. Nationally, about 93% of school children were vaccinated in the last school year, CDC data shows.

It’s not clear if there are pockets within the state that remain unvaccinated. Some other children may have only gotten one dose instead of the two needed for full protection. Also, the vaccine, while considered highly effective, doesn’t produce immune protection in about 3% of people. Babies who have not been vaccinated and immunocompromised people also remain vulnerable.

There was such a pocket of unvaccinated children in 2019 in Maryland. Following a large measles outbreak in an Orthodox Jewish community in New York, five cases were reported in children in Baltimore County. The infections prompted a mass vaccination effort that stopped the spread.

There have been no cases in Maryland in the three years after that outbreak, and only one each in 2023 and 2024, state health data show.

Vaccination rates remain less robust across the country, according to an analysis by KFF, a health research organization. It reported that 14 states had vaccination rates below 90% last year.

Compounding the issues, public health experts say, is Robert F. Kennedy Jr., the new U.S. health and human services secretary, who has played down the Texas measles outbreak and has been critical of vaccines generally for years. He has backed the widely debunked theory that the MMR vaccine causes autism in children.

“The MMR vaccine ... has been exhaustively studied and proven safe,” said Dr. William Moss, professor in epidemiology and executive director of the International Vaccine Access Center in the Johns Hopkins Bloomberg School of Public Health.

Moss said misinformation has depressed the vaccination rate and could cause more outbreaks nationally.

So far in Texas and neighboring New Mexico, 124 cases have been reported since late January. Moss said most cases are in a Mennonite community that is largely homeschooled and has no vaccine mandates.

Some of the telltale signs of measles in patients are a cough, red eyes, high fever and a rash. Children are much more susceptible than adults, largely because fewer of them are vaccinated.

Complications include pneumonia, brain inflammation and damage, and problems with pregnancy. Moss said the danger from measles can linger because the infection wipes out the body’s memory of bacteria and viruses. That can lean to a weakened immune system, making people more likely to become sick with other diseases for years after their measles infections.

In the United States, children typically get their first dose of vaccine when they are 12 to 15 months old and the second between ages 4 and 6. Those traveling internationally can get a dose as young as 6 months, but would still need the two doses later.

Moss said there is work to be done to help parents understand the risks from measles, and the safety of vaccines.

“It’s unfortunate that it takes a large measles outbreak to convince the American public once again that vaccines are valuable and important,” Moss said. “And just because we’re not seeing the disease here, because of high immunization coverage, doesn’t mean it can’t come back when we let down our guard.”