Maine has reached “herd immunity” for school-required vaccination coverage for the first time since 2011, driven by a law that went into effect in 2021 that eliminated philosophical and religious exemptions for students attending K-12 schools.

Herd immunity is achieved when at least 95% of a population is immunized against infectious diseases.

“Maine has become a leader in childhood vaccination,” Dr. Puthiery Va, director of the Maine Center for Disease Control and Prevention, said in a statement Tuesday. “It couldn’t come at a better time, as the United States has already seen more measles cases in the first three months of 2024 than in all of 2023. This alarming trend highlights the importance of childhood vaccinations, which reduce the risk that Maine’s youngest residents could face from these harmful and potentially fatal diseases.”

The U.S. CDC is reporting 125 cases of measles in 17 states (none in Maine) so far in 2024.

State lawmakers and the Mills administration prioritized improving Maine’s vaccination rates after years of high rates of religious and philosophical opt-outs left the state vulnerable to outbreaks of infectious diseases.

Lawmakers passed the bill in 2019, and it survived a people’s veto attempt that would have overturned the law before it was implemented. The new vaccine law went into effect in the 2021-22 school year.


Since then, as families have complied with the new requirements, vaccination coverage in schools has improved, plummeting from 4.5% opting out in 2020-21 – the last year before the law was implemented – to 0.8% in 2022-23 and 0.9% in 2023-24.

Medical exemptions are still permitted under the law, but religious and philosophic exemptions are no longer allowed.

Meanwhile, the percentage of students getting their first shots for diseases covered by school vaccination requirements – including measles, mumps and rubella, pertussis, polio and others – surpassed 95% for the first time since 2011, the Maine CDC said.

Herd immunity is the scientific term for when vaccination coverage among a population is so comprehensive that infectious diseases have few opportunities to gain a foothold. Public health experts say herd immunity is important in preventing highly contagious diseases from spreading in populations.

“Achieving herd immunity among schoolchildren represents a pivotal success for Maine,” Jeanne Lambrew, commissioner of the Maine Department of Health and Human Services, said in a statement.

The percentage of students immunized against specific diseases can differ from the overall vaccination rate for several reasons, primarily because of missing vaccination records. Even if a parent has their child vaccinated, the child will be listed as unvaccinated if the school doesn’t have the vaccination record to turn over to the state CDC.

Related Headlines

Comments are no longer available on this story

filed under: