Thousands of counties show the drop in childhood vaccinations as NBC News and Stanford detail their tracking methodology
Reported by NBC News ·
An update to the investigation
The 2026 data investigation updates “The Vaccine Divide,” which NBC News first published in September 2025. The methodology for the two projects is similar.
Gathering public records
The newsroom filed scores of document requests, including requests under the Freedom of Information Act. The materials came in different formats and required further processing.
Comparing rates across counties
NBC News standardized the varied data so vaccination rates could be mapped and compared. The analysis covered thousands of counties. The methodology was similar to the approach used for the original investigation, allowing the updated project to examine the data in a comparable way.
Key points
- The updated investigation uses data collected from June to October 2026.
- “The Vaccine Divide” was first published in September 2025.
- NBC News worked with infectious disease researchers at Stanford University.
- The data was standardized to compare vaccination rates across thousands of counties.