Amid a record-breaking national outbreak of measles, the number of Texans who exempt their children from vaccination for non-medical reasons took another big leap this past school year.

The number increased 14 percent in 2018-2019, continuing a 15-year-long trend that public health officials worry is leaving communities vulnerable to the resurgence of preventable diseases such as measles, which has been confirmed this year in 23 states, including Texas. The number of measles cases this year is the largest since 1994.

“Seeing non-medical exemptions increase again on a double-digit scale should create outrage for everyone,” Allison Winnike, president and CEO of the Houston-based Immunization Partnership, said in a statement. “It’s time for Texans to take action.”

Porfirio Villarreal, public information officer for the Houston health department, added that it’s “disappointing to see yet another rise in the number of parents opting out of life-saving vaccines, mostly due to the vast amount of misinformation on the internet and social media channels.”

RELATED: Vaccine exemptions on the rise among Texas students

The number of exemptions are still small, 64,176, but they represent a roughly 2,000 percent increase since 2003, when the state began allowing parents to decline immunization requirements for reasons of conscience. There were about 3,000 in 2003-2004, and a little under 57,000 in 2017-2018.

The new numbers are contained in a report released Monday by the Texas Department of Health Services.

The report says there are opt-out rates of more than 40 percent at some schools. Rates by schools are not publicly available, but the state health department does make them available by school districts — those numbers likely will be posted Tuesday, said a health department spokesman.

17 states allow waivers

The report comes as the national number of 2019 measles cases has reached 764, according to the Centers for Disease Control, some 20 years after the infectious disease was thought to be largely eradicated. Texas accounts for 15 of the cases.

“It’s unsettling that at a time when measles is returning nationally because of vaccine exemptions, the exemption trend in Texas continues to get worse,” said Peter Hotez, a Baylor College of Medicine infectious disease specialist. “It suggests a tone-deafness.”

Texas is one of 17 states that allow waivers of school vaccine requirements based on parents’ conscience or personal beliefs. Only three states — California, Mississippi and West Virginia — don’t grant exemptions on religious grounds. All 50 states allow exemptions for medical conditions, such as a compromised immune system.

No bill in the 2019 Texas Legislature has sought to change Texas’ conscientious exemption and those that attempt to make the process more transparent gained no traction. The latter includes one that would require the health department to publish the immunization opt-out rates for individual public schools and another that attempts to clarify that child care facilities can list their immunization opt-out rates for parents who are interested. Neither has moved out of committee.

A bill that would make it easier to opt-out of vaccines by putting the request form online never received a committee hearing.

Jackie Schlegel, president of Texans for Vaccine Choice, did not respond to a Chronicle request for comment. The organization in March rallied at the state Capitol to “lead the nation in this fight for our basic rights to freely raise our children and live our lives in the way we see fit without government intrusion or coercion.”

D-FW, Austin hot spots

Hotez, the Baylor infectious disease specialist, noted that the report shows the trend is disproportionately affecting urban areas around Austin and Dallas-Fort Worth. A report map shows four counties adjacent or close to Travis County — Burnett, Blanco, Kenall and Gillespie — with more than 3 percent of students claiming exemptions. Fourteen counties in the Dallas-Fort Worth area report 1.58 percent to 2.99 percent of students claiming exemptions, up from nine counties in that category last year.

Montgomery County is the only county in the Houston area in the same category. Less than 1 percent to 1.57 of students in Harris County claim exemptions.

Still, Villarreal encouraged parents to pay more attention to their family doctor and the CDC.

“Parents who discard 200 years of scientific evidence about vaccines and replace it with a 20-minute internet search could unintentionally put at risk the lives of their kids’ classmates or neighborhood friends,” said Villarreal.

todd.ackerman@chron.com