Several Lower Merion elementary schools started the 2025-2026 school year with kindergarten measles vaccination rates below the 95% level public health experts consider necessary for herd immunity.

Kindergarten MMR (measles, mumps and rubella) vaccination rates at those schools ranged between 76.9% and 94.7%, according to The Philadelphia Inquirer, which reviewed data from a new state database. At 95%, enough people are vaccinated to block the disease from spreading to those who are not.

The data landed as Lower Merion School District students returned to class on Tuesday, Sept. 8, and as Pennsylvania grapples with its worst measles outbreak in decades. The state reported 393 cases across 28 counties as of Tuesday, Aug. 25, and two deaths in Lancaster County that same day, the first measles deaths in Pennsylvania in 35 years. None of the patients diagnosed this year had been fully vaccinated.

Montgomery County has recorded only three measles cases as of Aug. 12, according to Mainline Media News. But the below-threshold rates at some Lower Merion schools mean pockets of kindergartners lack the protection that keeps the virus from gaining a foothold.

What parents can do

The clock is ticking. Pennsylvania law gives families five days after school starts to get children immunized or show proof of an appointment. After that, unvaccinated students must leave school until they receive the shot.

The Pennsylvania Department of Health published a searchable school-level immunization database on July 31, covering 2025-2026 data for kindergarten, seventh grade and 12th grade. Parents can look up their child's school by name.

When the state launched the tool, Pennsylvania Health Secretary Dr. Debra Bogen said it puts critical information in families' hands. "This new tool cuts through the noise, putting critical information directly into the hands of families and local leaders …" Bogen said in an Aug. 4 statement reported by the Times Herald.

Statewide and national picture

Across Pennsylvania, about 93% of kindergartners are immunized against measles. Roughly one in three kindergartners statewide attend a school where the MMR rate falls below 95%, according to WESA.

Nationally, the kindergarten MMR rate dropped to 92.4% during the 2025-2026 school year, the third straight year of decline and below the 95.2% recorded before the COVID-19 pandemic, according to CDC data reported by WESH.

Pennsylvania's philosophical and religious exemptions for required school vaccinations have tripled over the past decade. The state has among the most permissive exemption laws in the country.

Where to get vaccinated

Montgomery County residents who are uninsured or underinsured can get a free MMR vaccine at county health clinics in Norristown (610-278-5145) or Pottstown (610-970-5040). The state's Vaccines for Children Program covers eligible children at no cost; families can call 888-646-6864 for details. MMR vaccines are also available at CVS pharmacies.

For families whose children started school on Sept. 8, the five-day immunization deadline falls on Sunday, Sept. 13.