In the United States, only three states bar non-medical exemptions to school immunization rules, a policy shown to decrease the likelihood of an outbreak of vaccine-preventable diseases. Some lawmakers in Washington State, which is facing a measles outbreak with more than 60 confirmed cases, would like it to be the fourth.
The state's senate voted last week to advance a measure removing the personal and philosophical exemption for vaccines required for public school, the Spokesman-Review reports. One senator expressed doubt that the state's policies have harmed public health, but a large body of research shows that school vaccine mandates work.
In the U.S., students are required to get certain vaccines before attending public school; all 50 states allow exemptions for children with medical conditions that prevent them from getting vaccinated. Most states also allow some level of non-medical exemption: 47 for religious reasons, and 17 for philosophical reasons, sometimes defined as "moral, philosophical or other personal beliefs." (In states with religious but not philosophical exemptions, parents can easily claim a religious exemption when there is none.)
Only Mississippi, West Virginia, and California ban all three. Researchers say we're already seeing the consequences: A 2017 study found states with lax vaccine policies are 140 to 190 percent more likely to experience a measles outbreak compared with others. According to the Centers for Disease Control and Prevention, six outbreaks have been reported in the U.S. in 2019, all in states with some level of non-medical exemptions.
Although vaccination rates are already rising in Washington, as they typically do during an outbreak, researchers say that progress shouldn't require a public-health emergency. But combating the anti-vaccine movement has proved difficult: Coercive measures often fail to convince anti-vaxxers, and even Pinterest's more extreme crack-down on the spread of anti-vaccine propaganda has its faults.
In contrast, experts agree that laws banning non-medical exemptions are the surest way to increase vaccination rates. Skeptics have only to look at California, which had high exemption rates before lawmakers intervened: The first bill, which made it harder to get non-medical exemptions, didn't come in time to stop a 2015 outbreak of measles at Disneyland, which spread among a cluster of unvaccinated people. So that same year, the state banned non-medical exemptions, a change that's made it a model for immunization policy.
There's some evidence that this legislation has already helped, as the exemption rate has declined since its 2013 peak, and vaccination rates continue to climb. However, studies have found that progress has stalled due to implementation problems. "Some physicians may continue to write medical exemptions for vaccine-hesitant parents, potentially limiting the long-term impact of [the ban]," researchers wrote in the journal Pediatrics.
Even with California's success, the evidence for the reverse is perhaps more convincing. States that have not banned non-medical exemptions contain clusters of unvaccinated people with the ability to compromise herd immunity. As Pacific Standard has reported:
Anti-vaxxers pose a threat that extends well beyond their ranks: When the measles vaccination rate dips below 95 percent, it compromises herd immunity, which keeps the disease from spreading and protects those few people who cannot get vaccinated: young infants, the elderly, and immunocompromised adults.
In many of these clusters, researchers have linked state vaccine exemptions to higher rates of vaccine-preventable diseases such as pertussis (whooping cough). Parents in Texas, for example, filed 45,000 non-medical exemptions for the 2015 to 2016 school year. Now the state is facing a measles outbreak, with eight confirmed cases this year.
Could Washington break rank to follow California's model? State senators will likely decide within a few weeks, when the bill goes up for review, the Associated Press reports.