HARTFORD — New data released Thursday show more Connecticut students are being exempted from vaccinations for measles, mumps and rubella for religious reasons.

The overall number of religious exemptions in the state climbed by 25%, from the 2017-18 school year to the 2018-19 school year, according to the state's Department of Public Health. The agency said the increase from 2% of students to 2.5% represents the largest single year upturn in religious exemptions for vaccinations since it began tracking statewide data 10 years ago.

While the immunization rate for kindergarten students remains high in Connecticut, the new information shows it has declined from 96.5% to 95.9%.

"It does raise concern," said Public Health Commissioner Renee D. Coleman-Mitchell, adding how the new numbers warrant releasing more data, including county-by-county and school-by-school. The commissioner originally planned not to release the school-by-school data, but Democratic Gov. Ned Lamont on Wednesday overruled that decision, arguing the public should have the information.

A Bristol couple on Thursday asked a court to stop the release of the school-by-school vaccination rates, arguing they'll suffer "irreparable harm" if the information is released. Their unvaccinated son attends a private school where 18% of the students claimed a religious exemption from vaccinations, according to school-by-school data DPH released in May. The couple has another lawsuit pending.

"We believe that out of deference and respect for the authority of the court, no new data should be released during the pendency of this litigation," the couple said in a written statement. "To do otherwise is to move into the dangerous waters of undermining the separation of powers that is so important to our system of government."

Lamont's office declined to comment on the pending litigation.

Coleman-Mitchell said the resurgence of measles in the U.S. is of great concern and the decline in Connecticut's vaccination rates, coupled with the increase in religious exemptions, validates the need to release both county-by-county and school-by-school data by Oct. 21. There have been three cases so far in Connecticut this year.