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Two hotspots in Sonoma and Napa counties among Northern California cluster where lower vaccination rate could enable measles spread
The Press Democrat • • health
Key Points:
- Despite Northern California's overall high measles vaccination rate of 97.6%, Kaiser Permanente researchers identified seven "hot spot" clusters with lower-than-expected vaccine coverage, including areas in Sonoma and Napa counties, posing a risk for measles outbreaks.
- The study analyzed vaccination data for 7-year-old Kaiser patients and found 276 census tracts with coverage below 95%, highlighting localized gaps that may be masked by surrounding communities with higher rates.
- Public health officials emphasize that these pockets of lower vaccination increase the risk of measles transmission, especially in school settings, and stress the importance of targeted vaccination campaigns and education efforts.
- Limitations of the study include its reliance on Kaiser Permanente data, which covers only about one-third of the region's population, excluding uninsured families and those using other healthcare systems.
- With measles cases rising nationally—2,903 confirmed in the U.S. in 2026 so far—local health departments are using these findings to focus resources and outreach to communities at higher risk to prevent outbreaks.
