For years, Austin pediatrician Mai Duong watched in dismay as more and more parents opted out of common childhood vaccines that have saved millions of lives. Then, in 2015, a measles outbreak tracing back to Disney theme parks in California (and fueled by regional pockets of vaccine refusal) infected nearly 150 people across seven states.

“It just got to a point where we had to take action,” says Duong, chief of pediatrics at Austin Regional Clinic (ARC). “We see newborns and people near the end of life, and many of them can’t get vaccinated for medical reasons. They’re unprotected and very vulnerable—if measles were spread in our waiting rooms, it could be devastating.”

That was a risk Duong and her colleagues weren’t willing to take. A couple months after the Disneyland outbreak was declared over, ARC announced a policy of no longer accepting new pediatric patients whose parents refused childhood vaccines required for school entry, such as the measles-mumps-rubella, or MMR, vaccine.

“That was the best tool we had to protect our patients,” Duong says. “Vaccines have been so successful that lots of parents haven’t had any experiences with or even heard stories about these diseases. There’s so much misinformation out there that sometimes the fear of vaccines is greater than fear of the diseases they prevent.”

Before 1963 (when a measles vaccine became available in the U.S.), up to four million Americans caught the highly contagious virus every year, leading to nearly 48,000 hospitalizations and hundreds of deaths. But after decades of immunization campaigns and public investment, experts declared in 2000 that measles was eliminated in America—a landmark moment for the country’s public health.

And yet, sustaining that progress has proven to be increasingly difficult. Less than three months ago, the U.S. nearly lost its measles-free designation after another outbreak erupted across the country and topped 1,200 cases in 31 states (Texas included), the highest number in the country since 1992. Luckily, none reached Travis County. “We really dodged a bullet last year,” says Mark Escott, interim health authority and medical director for Austin Public Health. “There’s substantial public health risk to our city and county because of our high vaccine exemption rates.”

These troubling vaccine refusal trends aren’t coincidental: They’re fueled by an organized anti-vaccine movement, lenient exemption laws, and a steady online flow of misinformation and conspiracy theories about the effects of vaccinations. In fact, a recent study found that spreading false information about vaccines is a favorite topic among Russian trolls and social media bots seeking to sow division among Americans.

In 2003, Texas legislators passed a law allowing parents to seek an exemption to school-entry vaccines for “reasons of conscience.” (Texas already allowed exemptions for medical and religious reasons.) Since its passage, nonmedical vaccine exemptions have soared from roughly 2,300 Texas children during the 2003-’04 school year to more than 64,100 by 2018-’19.

Unfortunately, the troubling trend hasn’t skipped Austin. According to Austin Public Health, rates of conscientious vaccine exemptions in Travis County rose from 1.53 percent in 2011-’12 to 2.72 percent in 2017-’18. That translates to an increase of about 80 percent, Escott notes, pointing out that groups of unvaccinated children are emerging in hyper-localized pockets around the city. For example, most of Austin’s public schools have high immunization rates, but that’s not the story at many of its private schools. At the Austin Waldorf School, the nonmedical exemption rate for kindergarteners is nearly 53 percent. It’s almost 37 percent at Austin Discovery School.

Back in 2018, a study found that four Texas cities—including Austin—were at special risk for an outbreak of vaccine-preventable disease. But as measles broke out across the country the next year, state lawmakers tried to make it even easier to claim an exemption, pushing for laws like HB 1490, which would have barred state health officials from maintaining a record of vaccine exemptions. “I think we’ll eventually see a measles outbreak in Austin,” says Peter Hotez, who co-authored the 2018 study and is a professor of pediatrics and dean of the National School of Tropical Medicine at Baylor College of Medicine. “It’s inevitable that Texas will have a serious measles epidemic and, when that happens, people will look to our elected representatives and realize they were among the enablers.”

The encouraging news is that most Texans still support mandatory childhood vaccines. Hotez believes that the majority of parents are just looking for good information in a sea of online confusion.

At ARC, Duong says a key to vaccine uptake is having open, honest discussions with parents. But, she says, getting rid of nonmedical vaccine exemptions—like state legislators just did in Maine—is the quickest way to protect the city’s immunity. “We’re vulnerable to a measles outbreak,” Duong says. “It’s a constant worry more than an urgent worry. It’s kind of the way of life now.”

In late December, after this story went to press, Austin Public Health reported the first case of measles in Travis County in 20 years.