In the decade before the measles vaccine surfaced in the early 1960s, nearly all children in the U.S. had a case of it by their mid-teen years, according to the Centers for Disease Control and Prevention. Each year, an estimated 400 to 500 people died, 48,000 were hospitalized, and 1,000 suffered brain-swelling encephalitis from measles.

Measles-inflicted suffering and death are avoidable now, of course, thanks to routine childhood shots; and the highly contagious illness was declared eliminated in the U.S. in 2000. However, now, due to dangerous misinformation, some parents fear vaccines more than the diseases they fend off.

In our islands and elsewhere, the trend of “vaccine hesitancy,” or resistance to available lifesaving vaccines, is a growing public health threat. Like most states, Hawaii requires schoolchildren to get immunizations, but parents can seek exemptions for medical or religious reasons. In recent years, the statewide exemption rate for religion has topped 1 percent, more than doubling rates of a decade ago.

While the rising rate may seem insignificant, consider that research shows that people who refuse vaccines tend to group together in communities, including schools. Haleakala Waldorf School on Maui and Malamalama Waldorf School on Hawaii island have relatively small enrollments — 245 and 95 students, respectively. But they have the largest count of religious exemptions — both private schools hover in the neighborhood of 50 percent.

When infectious disease gets into communities with pockets of unvaccinated people, difficult-to-control outbreaks are more likely to occur. The upshot, in the case of measles, is that we’re vulnerable to having the virus re-establish itself in our country.

In Hawaii, according to the state Department of Health’s self-reported school data, the pockets are deepest on neighbor isles. All of the schools on the state’s top-10 list for religious exemption (2018-19) are on neighbor islands, half on Kauai. Overall, half on the list are private schools.

The combination of growing vaccine hesitancy and the annual flow of millions of visitors into Hawaii leave the state especially vulnerable. Measles is still a big problem in other parts of the world, and travelers infected abroad can bring the virus back and spread it. This year, Japan and the Philippines are grappling with hard-hitting outbreaks.

California is one of the few states that has stripped away any “personal belief” type of vaccine exemption for children in both public and private schools. The move was a much-needed step in the right direction; and Hawaii should follow suit.

In the 2014-15 school year, when parents could still opt out of vaccinations for any reason they chose, 90 percent of kindergartners in California public schools were fully immunized — well below the 94 percent mark that establishes “community immunity,” according to experts.

The gap helped prompt the state to enact a law requiring every child taught in school classrooms or enrolled in a child care facility to be fully immunized against 10 diseases, ranging from measles to whooping cough (pertussis), unless a doctor provides a medical reason for why it’s unsafe to do so.

The hard science supporting pro-vaccine public health information, such as that issued by the CDC, is typically presented in a manner that’s less dramatic than easy-to-find-online anti-vaccine propaganda that seems to support a collective amnesia.

But as Hawaii’s Health Department recently noted — in the aftermath of two cases of unvaccinated visitors to Hawaii island falling ill with measles — some facts are indisputable. Among them: Immunization through vaccine is the safest way to protect against disease; and that if we stop vaccination, deadly diseases will return.