Delaware County kindergartners started school this fall with MMR vaccination rates just below the level the CDC says is needed to prevent measles outbreaks, as a federal dispute over Pennsylvania's death count raises the stakes for local families.
The county's kindergarten MMR rate was 94.3% during the 2024–2025 school year, according to the Delaware County Health Department. That falls just short of the 95% herd-immunity threshold. Radnor Township School District schools reported rates above 95%, according to Patch.
Pennsylvania law gives families five days after school starts to show proof of immunization or an appointment. After that, students must leave school until vaccinated.
The vaccination pressure comes as CDC Director Dr. Erica Schwartz ordered two Pennsylvania measles-associated deaths excluded from the agency's national weekly tally, 6abc reported Thursday, Sept. 3. The decision, attributed to Schwartz by two people with knowledge of it, is a sharp break from the CDC's longstanding practice of accepting state-reported data.
Pennsylvania announced the two deaths on Tuesday, Aug. 25. Both victims were unvaccinated Lancaster County residents. One was a newborn infant. The deaths were the first measles fatalities in the state in 35 years.
The state Department of Health said it provided all required epidemiological data to the CDC. But when the agency posted its weekly update, the deaths appeared only as a footnote with an asterisk, stating the CDC could not yet determine whether measles caused or contributed to the fatalities.
"For the CDC, let alone the CDC director, to overrule that sort of determination and just put that vague language up on the website, it's more than atypical … It is the definition of the politicization of public health," Dr. Nirav Shah, former CDC principal deputy director, told 6abc.
Shah said the standard protocol for counting infection-associated deaths has long included anyone who tested positive and died within about 10 days, without requiring a final determination of cause. Dr. Deb Houry, former CDC chief medical officer, said a measles-associated death in New Mexico last year was added to the national total even while still under investigation.
The dispute escalated after HHS Secretary Robert F. Kennedy Jr. suggested the Pennsylvania deaths may have been "altogether fabricated." Gov. Josh Shapiro called those claims "inaccurate and misleading." At a Lancaster press conference on Aug. 25, Shapiro said information from the federal government that isn't "driven by facts and by science" makes it "even more confusing for parents," The Hill reported.
HHS press secretary Grace Davis Jamison said in a statement that the deaths have not been confirmed based on information available to the CDC.
Pennsylvania's outbreak has grown to 540 confirmed cases across 36 counties, with 91 hospitalizations, according to the state Department of Health. More than 46,000 MMR vaccines were administered statewide in August, nearly double the typical monthly pace.
Statewide, about one in three kindergartners attended a school where MMR rates fell below 95% during the 2025–2026 school year, WESA reported. Lancaster County Coroner Dr. Stephen Diamantoni said his office is also investigating another recent death in a child who tested positive for measles.
