When parents can no longer get "personal-belief" exemptions from childhood vaccinations, they may get around it by asking for religious exemptions for their kids, a new study finds.
Researchers found that after Vermont banned personal-belief exemptions, the number of kindergartners with religious exemptions from vaccination suddenly shot up -- from 0.5% to nearly 4%.
That kind of increase almost certainly means that many parents who wanted to avoid vaccines simply switched tactics, according to Dr. Paul Offit, a pediatric infectious disease specialist who was not involved in the study.
"Either parents in Vermont suddenly became very religious, or they started using religious exemptions as a replacement," said Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia.
He said the more than sevenfold increase in religious exemptions among kindergartners is worrisome, since vaccination only works as a public health strategy when enough people are immunized. And it's likely, Offit noted, that exemptions were concentrated within certain communities.
With old childhood diseases like measles and mumps making a comeback in recent years, a number of U.S. states have tightened up their laws on vaccine exemptions. Several states that used to allow kids to skip vaccines due to parents' "personal beliefs" no longer do.
Vermont is one, having eliminated its personal-belief exemption in 2016.
But parents there can still ask for exemptions based on religious beliefs -- as is the case in 45 U.S. states and Washington, D.C.
The new study, published online Nov. 4 in Pediatrics, aimed to see how exemption patterns changed after the policy took effect.
Overall, nonmedical exemptions among kindergartners declined -- from 5.7% to 3.7%, the findings showed.
To policymakers, that could look like a clear success, said Dr. Joshua Williams, lead researcher on the study. But underlying the overall decline was a sharp rise in religious exemptions.
From 2011 through 2016, the average proportion of kindergartners with religious exemptions was 0.5%. After that, it rose to 3.7% through 2018.
That suggests a "replacement effect," according to Williams and his colleagues at the University of Colorado and Denver Health Medical Center.
Currently, 15 states allow personal-belief exemptions. It's not clear, Williams said, whether they would see the same shift Vermont did if they eliminated those exemptions.
But, he said, other evidence suggests they could.
Looking at all U.S. states, the researchers found that rates of religious exemption were tied to whether a state allowed exemptions due to personal beliefs. States that allowed both were only one-quarter as likely to have kindergartners with religious exemptions, compared to states that allowed religious exemptions only.
Offit said, "I think this shows, in stark relief, that this is not actually a religious issue for most people."
In fact, Williams noted, all major religions now support vaccination.
Five states currently bar any nonmedical exemptions, according to the National Conference of State Legislatures. They include California and New York, where large measles outbreaks prompted lawmakers to toughen their rules.
In Offit's view, the Vermont experience "could be seen as an argument to eliminate all nonmedical exemptions."
But determined parents may find ways around that, too. After California got rid of nonmedical exemptions, medical ones rose over the next two years in areas that previously had relatively high rates of nonmedical opt-outs, a recent study found.
Overall, vaccination rates among U.S. children do remain high. Government figures show that among children born in 2015, only 1.3% had not received any vaccines by age 2 -- though that was up slightly from a few years before.
The "vast majority" of U.S. parents, Williams said, do view vaccines as safe and effective. He suggested that more of them "make their voices heard" when lawmakers are considering changes in vaccine-exemption policies.
"Parents should speak up, contact their elected representatives, and help make our communities healthier for everyone," Williams said.
The American Academy of Pediatrics has more on vaccine safety.