Case in point: This week, Texas state lawmakers voted to prohibit doctors from vaccinating foster children when performing initial medical exams. The amendment, introduced by Rep. Bill Zedler, a member of the Texas Freedom Caucus, centers on the argument that parents’ have the right to choose whether their children are vaccinated.

In many states parents can refuse to vaccinate their children for religious and philosophical reasons. This is becoming a more popular option in Texas, where personal-belief exemptions rose from around 2,300 in 2003 to nearly 45,000 in 2015. As a result, once-eliminated diseases are making a comeback (to stop a disease from spreading, researchers estimate around 95% of the population must be immune). A rash of measles cases have swept the country in recent years, including a 2013 outbreak in Texas that sickened 21 people, many of them children.

But Zedler is apparently unconcerned about the implications of his amendment, perhaps because he fundamentally misunderstands how vaccinations work. Per CNN, when asked by another state representative whether he believed they are important for the public health, he responded with a resounding: “No, I would not agree with that.”

Despite fierce questioning from fellow state reps, the amendment passed, the latest in a string of indicators that anti-vaccination sentiment is gaining steam.

Much of this initial distrust stems from a now-retracted 1998 study, which claimed to find a link between childhood vaccinations and autism. Although it was later revealed that author Andrew Wakefield had falsified results—subsequent large-scale studies disproved a connection—a seed was planted. Over the past two decades, this seed has grown into a snaking vine, nurtured by a number of vocal conspiracy theorists. For years, the movement’s most famous voice was Jenny McCarthy. The actress has publicly and repeatedly insisted that her son’s autism diagnosis was caused by a series of vaccines he received as a child.

Her crown has since been usurped. Today, the most high-profile peddler of rhetoric linking vaccines to autism also happens to be the President of the United States.

Healthy young child goes to doctor, gets pumped with massive shot of many vaccines, doesn't feel good and changes – AUTISM. Many such cases!

— Donald J. Trump (@realDonaldTrump) March 28, 2014

President Trump has long dealt in these debunked theories, an activity that hasn’t stopped since the election. (Wakefield, the father of the anti-vaccination movement, was a guest at his inaugural ball.) Health experts worry Trump’s rhetoric might cause parents across the country to stop vaccinating their children.

This, coupled with legislation such as the amendment passed in Texas and the rise of laxer vaccination exemption laws, suggests we could be reaching a breaking point. Already, vaccination rates at many schools in the state are well below the protective benchmark of 90% to 95%. If this trend continues, and immunity rates slip across the country, we could see a sharp rise in preventable disease outbreaks. This month, for example, nearly 50 people were infected with measles in Minnesota. The outbreak, the state’s worst in three decades, mostly affected Somali-American children in Minneapolis.

The community’s vaccination rate dropped significantly over the past decade after anti-vaccination activists, including Wakefield himself, began visiting families in the area.