Assistant professor Kenneth McCall prepares a measles, mumps, and rubella (MMR) vaccination at the Portland Community Health Center in this March 9, 2015, file photo.

Gov. Janet Mills signed a bill in May tightening vaccination rules for attending school in Maine, but the stricter requirements don’t apply to one group of students.

A provision in the law will grandfather in special education students and allow them to continue opting out of vaccinations on religious and philosophical grounds for several years after other students no longer have those options.

The new law is an attempt to boost Maine student vaccination rates among kindergarten students that have fallen below the 95 percent level public health experts say establishes “herd immunity” — a level at which even students who aren’t vaccinated are protected from contagious diseases. Those rates have fallen as more parents claim religious or philosophical exemptions from school vaccine requirements for their children.

But the provision for special education students will delay, likely by more than a decade, the date when no student will be able to claim those types of exemptions from the vaccine rules.

[Janet Mills signs bill ending religious and personal exemptions for vaccinations]

Generally, students attending Maine schools are required to be immunized against contagious diseases such as varicella, measles and pertussis, but state law has traditionally allowed three types of exemptions: medical, philosophical and religious. As more parents have claimed the nonmedical exemptions for their children — something they do by submitting a form to their children’s school at the start of the academic year — vaccination rates at almost half of elementary schools have fallen below the 95 percent herd immunity level.

The bill Mills signed into law last month, LD 798, makes Maine the fourth state in the country to ban non-medical exemptions, after Mississippi, California and West Virginia. But the exception for special education students keeps those exemption options in place for about 15 percent of Maine’s public school students.

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To be eligible for this provision, students receiving special education services need to have claimed a religious and philosophical exemption before September 2021, when the law takes effect. New special education students will not be able to claim non-medical exemptions after September 2021.

None of the other three states that have banned non-medical exemptions has such an exception in place.

There’s no medical reason why all special education students should be able to opt out of vaccination requirements, according to Dora Mills, the chief health improvement officer for the MaineHealth hospital system and a former director of the Maine Center for Disease Control and Protection.

“Just because you have an individualized education plan does not mean you should get a religious or philosophical exemption,” she said. “It doesn’t make sense from a medical standpoint.”

According to the latest Department of Education data, 5.6 percent of students claimed non-medical exemptions in the 2018-19 school year, more than double the national rate. There are no data available on the percentage of special-education students claiming nonmedical exemptions.

“We’re losing herd immunity and these diseases are coming back,” Mills said.

[Vaccination rates continue to drop among Maine schoolchildren]

Rep. Ryan Tipping, D-Orono, who sponsored the bill, said special education students were grandfathered in as part of a compromise with groups who opposed tighter vaccine laws. The carve-out for those students was in the first version of the bill Tipping proposed.

“It was in direct response to their concerns around the homeschooling challenges posed by the special needs of some students,” he said.

If Maine parents object to vaccinations for their children after the law takes effect in September 2021, they can choose to homeschool them. But that might be difficult for parents of special education students, who might not have the additional resources or expertise to meet special education needs at home.

“In an effort to provide the best for their child, families with children with special needs often investigate the option of homeschooling,” said Kathy Green, co-founder of the parent group Homeschoolers of Maine. “Without an exemption, the vaccine requirements would surely push many more in this group toward the option of homeschooling.”

In the 2016-17 school year, about 15 percent of Maine students between ages 6 and 17 received special education services. If 5.6 percent of those students continued to claim religious or philosophical exemptions, the number of students opting out of vaccine requirements would amount to less than 1 percent of the total student population.

That group is small enough that herd immunity would not be impacted, experts said.

“It’s a clearer system to enforce, and ultimately it’s going to be a small enough population,” said Ross Silverman, a Health Policy and Management professor at Indiana University-Purdue University Indianapolis. “From a public protection perspective, I think it’s a solid compromise.”

[Thousands of US kindergartners unvaccinated without waivers]

Special education students are a well defined and vulnerable group who have historically found it hard to access public education. So the exception for those students eliminates the additional hurdle of vaccination for special education students already in school, Silverman said.

Since no new student who first qualifies for an individualized education plan — which outlines the special education services a student should receive — after 2021 will be able to claim a non-medical exemption, the population of special education students in the school system with religious or philosophical exemptions will continue decreasing. But it will be a carve-out in the law that exists until those students graduate.

Bill sponsor Tipping said that will not hurt efforts to ensure herd immunity.

“Medical experts that I consulted indicated that the amount of students that this would grandfather will not pose a threat to community immunity thresholds,” Tipping said. “The goal of the bill is to protect children. To that end, I wanted to make sure there was plenty of time to get caught up and make reasonable accommodations for people who brought forward concerns.”