Nearly a decade ago, Pennsylvania officials were urged by a special state commission to make school vaccination rates public so that parents could better track immunization levels and put the spotlight on schools that were not complying with the state mandates.

After years of the state’s inaction on that plan, the Post-Gazette has now made those rates available to help track an alarming decline in vaccine protection in hundreds of schools across the state.

An analysis of thousands of records dating back to 2017 shows for the first time the critical breakdowns — including the state’s own role — that led to classrooms becoming increasingly unsafe as infectious diseases like measles surged nationwide.

The investigation found that nearly two-thirds of Pittsburgh kindergarten classrooms are below herd immunity for measles, and statewide nearly one in 10 students — at least 40,000 — are either not fully vaccinated or don’t have the required exemptions.

The reporters found that local school officials are failing to enforce the rules despite increased warnings from public health experts about the dangers of the disease.

The Post-Gazette, in collaboration with the FRONTLINE (PBS) Local Journalism Initiative and with support from The Heinz Endowments and the Pulitzer Center, spent six months investigating the falling rates and the forces driving the historic change that has taken place since the pandemic.

The newspaper also created a searchable database for families to track their own schools and the rates of required school vaccines.

In analyzing the data from the state Department of Health — more than 4,500 public and private schools — the reporters found the rates have plummeted for every vaccine.

Those include shots that protect children from pertussis (whooping cough), polio and Hepatitis B.

But the Post-Gazette focused on the measles vaccine because the disease is far more contagious than the other illnesses and is now spreading at levels the country has not seen in more than a generation.

While much has been written about vaccination rates at the county and state levels in the U.S., the Post-Gazette focused on schools, where many of the outbreaks begin before spreading into nearby communities.

To identify where those schools are located, the newspaper plotted them using geolocating software, allowing reporters to pinpoint areas that could be vulnerable to outbreaks.

Reporters traveled across the state, interviewing dozens of parents, school leaders, medical experts and lawmakers, and reviewed thousands of records including lawsuits, academic studies, campaign finance filings, legislative reports and social media posts.

Many of the changes are rooted in the COVID-19 pandemic — a period of turmoil when fights broke out over school shutdowns and mask mandates, and misinformation campaigns launched by Children’s Health Defense and other groups raised doubts about the safety of the coronavirus vaccine.

The Post-Gazette also turned to the University of Pittsburgh’s Public Health Dynamics Laboratory, which simulated measles outbreaks at the schools using a novel computer program known as FRED — the Framework for Reconstructing Epidemiological Dynamics.

Drawing on detailed information about the people in a given area — ages, travel habits and the number of school-aged children in each household — the simulations showed how a single case of measles could spark an outbreak, and potentially a public health crisis.

The Post-Gazette’s goal was to obtain as much data as possible — including the most current numbers available for all the schools across Pennsylvania.

However, the state health department withheld data on hundreds of schools with fewer than 20 students in each grade, saying immunization records could be used to identify individual students in classrooms that small.

Another 152 schools were removed from the latest school year due to apparent data entry errors.

Despite those gaps, the data — which includes the most current numbers available, from the 2024-2025 school year — is far more comprehensive than anything that’s publicly accessible in Pennsylvania.

In addition to the stories and a searchable database, the Post-Gazette and FRONTLINE are partnering on a documentary that will be incorporating much of the reporting for this project.

Special Note: To help carry out this project, the Post-Gazette collaborated with journalism students from Northwestern University’s Medill Investigative Lab in Washington, D.C. Melissa Dai and Isaiah Steinberg contributed to this report.

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