Kindergartens in Boston have some of the lowest measles vaccination rates in the state, according to data from the Department of Public Health, with many students falling into the “immunization gap” or having no vaccination record on file at the school.

“It’s a public health issue,” said Krista Magnuson, a parent of two Boston Public School students. “I am worried about those kids, I want them to have appropriate health care.”

Of the top 40 kindergartens in Massachusetts with the lowest measles vaccination rates, 19 of them are Boston schools, according to DPH immunization data based on a self-reported survey.

State law requires kindergarten through sixth-grade students to have two doses of the measles vaccine and laboratory evidence of immunity.

Dr. Andrew Zimmerman, a pediatrics professor at UMass Medical School said the highly contagious and potentially deadly infection can spread at schools like “wildfire,” and kids with poor access to health care are falling through the cracks.

“There hasn’t been enough advertising or public information on the importance of vaccines,” Zimmerman said.

In Mattapan, just 59% of Ellison Parks Early Education School students had been vaccinated against measles last year, with 40% of students falling under the “immunization gap” defined by DPH as not having all required vaccinations, without a religious or medical exemption.

In East Boston, 60% of kindergartners at Mario Umana Academy got the vaccine and 63% of Dorchester students at O.W. Holmes School was vaccinated while a quarter of those students had no immunization record on file.

Dr. Richard Moriarty, a pediatric infectious disease specialist at UMass Medical School, said poor record-keeping may play a role, but he called schools with low immunization rates “an outbreak waiting to happen.”

“When there are pockets of low immunization, anyone from anywhere can bring measles in,” said Moriarty, adding that measles is more contagious than Ebola and influenza.

BPS spokesman Xavier Andrews said for students who are not compliant, “documentation may include proof of an upcoming immunization appointment. In such cases, our school nurses and district health services staff will follow up with families to make sure immunizations are complete.”

Andrews said in cases where students are not vaccinated, there may be a lack of access to health care or the student may be foreign.

“Our nursing staff has a specific focus on supporting our families with obtaining the required immunizations when school begins, and diligently pursuing any missing documentation thereafter,” said Andrews.

If a BPS parent would like to obtain a religious exemption for their child, they must submit a letter stating vaccination is against their “sincere religious belief.” BPS collects immunization documentation upon registration and if a student is noncompliant, school nurses send letters and call parents.

DPH spokesman Omar Cabrera said sometimes data is not available when schools respond to the survey, making the “immunization gap” in part a  record-keeping issue.

But BPS parent Lisa Green said, “We don’t know if kids are immunized or not.”

“I remember going to my daughter’s first day of kindergarten with a baby in a baby carrier and I would have been concerned to go if I knew there were kids who weren’t vaccinated,” Green said.

The number of religious exemptions for kindergartners in the state has risen from 147 in the 1987-88 school year to 749 in the 2018-19 school year, according to DPH, but Suffolk County has the lowest exemption rate in the state.