State and local public health officials say they are concerned about the rising risk of disease in schools as more parents across the state each year have opted their children out of otherwise mandatory vaccinations.

A growing number of parents in Frisco ISD have filed for vaccine exemptions since 2003, when state lawmakers expanded the exemption process to include reasons of conscience, rather than only medical or religious reasons.

Districts are required by law to report the number of conscientious exemptions to the Texas Department of State Health Services each year. In the 2015-16 school year, the most recent in which data were collected, the rate of students in FISD who had filed for vaccine exemptions rose to 2.05 percent—more than double the state average.

“Frisco ISD takes the health and safety of our students very seriously and is committed to fostering the best possible learning environment for all,” FISD’s Assistant Director of Communications Meghan Cone said.

A similar pattern can be seen in other districts in Denton and Collin counties, both of which had some of the highest exemption rates of the state’s 254 counties at 2.05 percent and 1.92 percent, respectively.

The trend, if it continues, threatens to undermine what vaccine researchers call herd immunity, where a population’s high vaccination rates help slow the spread of vaccine-preventable diseases, protecting both the unvaccinated and the people for whom vaccines are not fully effective.

Matt Richardson, Denton County director of public health, said the herd immunity in Denton County schools is already being undermined.

“Having twice the state average, that’s a concern to us because we believe vaccines are a good way to prevent communicable and infectious diseases,” Richardson said. “So we think [vaccination] is a good way to protect the public, and we think a 2 percent number is still too high.”

Although the state health agency does not yet recognize a “significant concern statewide” as a result of the trend, an agency spokesperson said the risk of outbreaks increases as vaccination rates continue their steady decline in school districts throughout Texas.

“There’s not a number that I think we can point to that at ‘X,’ it’s going to be a problem,” said Chris Van Deusen, a spokesperson for the agency. “It’s really kind of a sliding scale, if you will. The more unvaccinated individuals you have, the more likely you could have some sort of outbreak.”

Policy and demographics

At least two proposals being considered by the Texas Legislature this session would make it more difficult for parents to obtain an exemption. House Bill 241 would require a doctor’s consultation before parents obtain an exemption; HB 126 would require parents to first review online education materials.

Another bill, HB 1124, would make it easier to obtain an exemption by making the relevant forms available for download on the state health agency’s website, simplifying the current multistep process.

Some have organized to lobby against legislative efforts to curb exemption rates, including Keller-based Texans for Vaccine Choice.

“These bills would place a barrier between parents and their exemptions,” said Rebecca Hardy, the group’s director of state policy. “These bills also assume the parents that are requesting these exemptions are uneducated, when in fact all the research shows that those that choose personalized vaccination schedules are, in fact, quite educated.”

A government study of data from the 2009 National Immunization Survey found that parents who delay or refuse vaccinations for their children are more likely than the average person to have graduated from college and have a household income at least four times the federal poverty line. Nearly half of Collin County residents age 25 and older have a bachelor’s degree compared with 30 percent nationwide, and the household income for a family of three was $84,735 in 2015. About 40 percent of Denton County residents have a bachelor’s degree and the median household income in 2015 was $75,050, according to the U.S. Census Bureau.

The Centers for Disease Control and Prevention analyzed survey responses from a sample of 11,206 children and determined children were vaccinated at lower rates across the board if their parents believed vaccines could result in serious side effects or that too many vaccines could overwhelm a child’s immune system.

The study also found parents who delayed and refused vaccines are more likely to be white than those who neither delayed nor refused. About 60 percent of residents in Denton and Collin Counties are non-Hispanic white.

Richardson said it is difficult to pinpoint the reasons why parents choose not to vaccinate their children since they are not required by law to specify on the exemption form. However, he did say a trend exists among parents who choose to enroll their children in private schools and not vaccinate.

“It’s very clear when you look at the numbers in the exemption data that private schools have a much higher rate on average, some as high as 13 percent,” Richardson said.

Hardy, after citing a handful of examples of private and charter schools that have high exemption rates and no recent disease outbreaks, said her group promotes access to exemptions without weighing in on the scientific consensus on declining vaccination rates and herd immunity.

“They’re following their religious and other deeply held convictions,” Hardy said of parents filing for exemptions.

But state health officials say such examples of small populations that avoid outbreaks are not reflective of the broader risks associated with declining vaccination rates. For an outbreak to occur, Van Deusen said, it is not enough to simply have low vaccination rates; the disease, made rare by the widespread use of vaccines, must also be reintroduced to the population.

Diseases such as measles are sometimes introduced after a person close to the community travels to another country where the disease is still circulating, Van Deusen said. In 2013, a large church northwest of Fort Worth that promoted skepticism of vaccines had nearly two dozen cases of measles after a member contracted it while visiting Indonesia, he said.

Monitoring rates

FISD hosts several immunization clinics each summer before the coming school year to make shots readily available to families, Cone said.

“Frisco ISD strongly encourages all families to vaccinate their children, as it protects the individual student’s health and that of the entire community,” she said. “At the same time, Frisco ISD respects the law and each family’s individual decision regarding vaccines.”

The state agency that compiles the exemption rates each year does not analyze it in detail, leaving that up to independent researchers, Van Deusen said. And since no hard cutoff exists for what exemption rates are considered too high, the state offers districts little guidance on that question.

He said because exemptions are lawful, the state has limited tools for addressing vaccination rate increases.