The number of Connecticut schools with a measles, mumps and rubella vaccination rate below 95 percent for kindergarteners — the Centers for Disease Control's threshold for herd immunity — increased to 134 in the 2018-19 school year from 102 the year before, according to school-level data the state Department of Public Health released Monday.

The MMR vaccination rate for kindergartners in Connecticut was 96.1 percent last school year, down from 96.5 the previous year and 97.1 in the 2012-13 school year. The statistics are for schools with more than 30 kindergartners, which excludes many private schools.  

State Epidemiologist Dr. Matthew Cartter said the increase in the religious exemption rate from 2 to 2.5 percent last year was the largest single-year increase the state has ever seen.

"It may be time, and we don't want to wait until it is past time, to remove the religious exemption," he said, noting this controversial decision is up to state legislators. DPH Commissioner Renee Coleman-Mitchell has recommended that nonmedical exemptions be repealed.

Cartter said that 40 schools have kindergarten MMR vaccination rates below 90 percent, putting them at risk for a measles outbreak, and that the rural counties have the highest rates of religious exemptions.

Asked to talk more about measles, Cartter noted that before vaccines were developed beginning in the 1960s, 3 million to 4 million people in the country were infected every year, of whom 48,000 were hospitalized and 400-500 died.

Some parents seek vaccine exemptions because they fear that materials in the vaccines can causes autism. But a 1998 paper linking the measles vaccine with autism has been debunked by scientific studies.

In southeastern Connecticut, the schools that were previously above the 95 percent threshold but dipped below last year are S.B. Butler Elementary School in Groton, Gallup Hill School and Ledyard Center School in Ledyard, Winthrop STEM Elementary Magnet School in New London, Mile Creek School in Old Lyme and Oswegatchie Elementary School in Waterford.

Conversely, Norwich's Integrated Day Charter School's MMR vaccination rate increased from 81.8 to 97 percent while that of Oakdale School in Montville increased from 94.4 to 95.7 percent.

Overall, 13 public elementary schools in southeastern Connecticut saw their MMR rates go up while rates decreased at 18 schools and stayed the same at four. Of those four, three had 100 percent MMR vaccination rates the past two years: Thomas W. Mahan Elementary School and Wequonnoc Arts & Technology Magnet School in Norwich, and Quaker Hill Elementary School in Waterford.

The local school with the lowest kindergarten MMR vaccination rate is Catherine Kolnaski STEAM Magnet School, at 80 percent.

The state did not release vaccination rates for many private elementary schools, as they reported fewer than 30 students. But statewide, the department said the MMR vaccination rate is 92.4 percent in private schools, compared to 96.4 percent in public schools.

Crossway Christian Academy in Putnam reported the highest religious exemption rate in the state, at 41.7 percent. North Stonington Christian Academy and Wildwood Christian Academy, in Norwich, reported the sixth and seventh highest rates of religious exemptions, at 18.8 and 18.6 percent.

Cartter said out of 38,120 public and private kindergartners, 939 had religious exemptions and 86 had medical exemptions. He noted that parents whose children cannot be vaccinated for medical reasons find the school-level data "incredibly important" in deciding where to place their children in school.

"This information needs to be available to the public and lawmakers so they are not operating in the dark as they make decisions for their families and shape public policy," Gov. Ned Lamont said in a news release praising the release of the data. "I want to make it absolutely clear — nothing in the data that was released today identifies any individual student. Rather, it constitutes important public health statistical data critical to the ongoing debate on this trend, which is happening not just in our state, but throughout the country."

Senate Majority Leader Bob Duff, D-Norwalk, said in a statement that he is concerned with some of the low rates at some public schools and will work with public health officials to "determine what steps the state needs to take to protect our children such as removing religious exemptions."

A Connecticut couple had sued to block the release of school-level data, but a Superior Court judge dismissed their lawsuit in September.

Informed Choice CT, a coalition advocating for personal medical freedom and against medical mandates, tweeted on Monday that the Department of Health, majority leaders and press outlets were "weaponizing highly flawed health data to strip the rights of 700,000 CT schoolchildren."

e.moser@theday.com