Health researchers have been convinced the anti-vaccine movement is gaining traction in America. Earlier this year, Minnesota battled its largest measles outbreak in nearly 30 years — an outbreak sparked entirely by vaccine deniers. That scare was followed by a study in the prestigious medical journal JAMA showing large measles outbreaks have been on the rise in America recently, fueled by unvaccinated people.

These developments — along with the election of Donald Trump, who in the past has suggested vaccines hurt children and cause autism — have had the public health community increasingly concerned.

But now there’s early evidence that the number of parents refusing vaccines for their kids has actually plateaued, at least in recent years.

While vaccine refusal rates have overall increased since 2011, they leveled off 2013 through 2016, researchers writing in the journal Open Forum Infectious Diseases found.

The study, led by doctors at Emory University in Atlanta, examined the rates of nonmedical vaccine exemptions — or families who choose to waive kindergarten-entry vaccination requirements for their children, citing philosophical or religious reasons.

Between the school years of 2011 to 2012 and 2015 to 2016, the average nonmedical exemption rate increased to 2.04 percent, from an average of 1.58 percent. But from 2013 to 2016, the rate held stable. (This analysis excludes Mississippi and West Virginia, since they don’t allow nonmedical exemptions.)

Lead study author Saad Omer, a professor in global health, epidemiology, and pediatrics at Emory, said the data make him cautiously optimistic. While the overall vaccine exemption rate grew between 2011 and 2013, Omer said, it plateaued after that. And he suspects vaccine coverage may soon get even better.

During the study period, there were important legislative advances in vaccine policy, which went into effect after the study ended. In July of 2016, Vermont banished its philosophical exemptions, and California also did away with all nonmedical exemptions.

Legislation in other states generally seems to be heading in a more pro-vaccine direction. One JAMA paper looked at the 36 vaccine bills considered between 2009 and 2012: 31 wanted to expand them, making it easier to opt out of vaccines, while only five wanted to make vaccine exemptions more difficult to obtain.

None of the 31 anti-vaccine bills passed, while three of the five bills clamping down on vaccine deniers made it through. So while there was more activity from the anti-vaccine side, public health has been winning out in state legislatures.

Better still, Omer said, vaccines haven’t become a partisan issue, despite the fears they would under Trump. Many of the people Trump has installed in key health agencies — Francis Collins at the National Institutes of Health, Scott Gottlieb at the Food and Drug Administration, Brenda Fitzgerald at the Centers for Disease Control — are pro-vaccine, and vociferously so.

“So far the signs are encouraging,” Omer said.

Still, there are a few caveats to keep in mind here. The reassuring national averages in the study hide variation at the state and county levels.

In Texas for example, between 2003 and 2016, there’s been a 19-fold increase in vaccine refusals — and it hasn’t leveled of lately. “We are still seeing an aggressive increase in nonmedical exemptions [here in Texas],” said Peter Hotez, a pediatrician at Baylor College of Medicine, “with at least 52,000 last year, up from 45,000 the year before.”

Texas is one of those lax states that allows parents to get both religious and philosophical vaccine exemptions (unlike Mississippi, West Virginia, and California). Researchers have continually found these more permissive places have higher rates of vaccine refusals — a trend that appeared again in the Open Forum Infectious Diseases paper. In the study, the rate of exemptions was 2.41 times higher in states allowing both religious and philosophical exemptions compared to those that allowed religious exemptions only.

Taking the much longer view, since the early 1990s, vaccine exemptions have overall been trending upward. In one 2009 New England Journal of Medicine paper, researchers looked at the state-level rates of non-medical exemptions and found that, between 1991 and 2004, those rates increased from less than 0.98 percent to about 1.5 percent. According to the new study, we’re now hovering above the 2 percent exemption rate, which translates to thousands more unvaccinated children than just a decade ago.

So that plateau in exemptions in the study, from about 2013 to 2016, represents a few school years, not a long-term trend. For the sake of public health, let’s hope vaccine refusal rates stay put or trend downward. To move in that direction, more states should consider following California’s lead. Most states still allow vaccine exemptions for people with religious beliefs, and 18 states grant philosophical exemptions for those opposed to vaccines because of personal or moral beliefs. That’s too many.