Measles Vaccination Gaps Found in Contra Costa County

Even though Northern California boasts one of the nation’s highest overall measles‑vaccination rates, a recent Kaiser Permanente analysis uncovered a handful of surprisingly thin spots. Researchers dug into records of 7‑year‑old patients and pinpointed seven distinct clusters where coverage slipped under the 95 % level needed for herd immunity.

Those clusters span eight counties—from the North Bay down to Sacramento and even into Fresno—covering 242 census tracts and roughly 25,800 kids, or about 11 % of the children examined. Together, the areas posted a combined vaccination rate of 94.6 %, just shy of the benchmark set by public‑health officials.

The findings, published in JAMA Network Open on July 30, are more than a statistical footnote. They give local health departments a map of neighborhoods that could become flashpoints if measles makes a push back into the United States. The timing feels ominous, as the country is already seeing a surge in cases.

Measles was declared eliminated in the U.S. in 2000, meaning the virus no longer circulates end‑to‑end, but it can still be re‑imported by travelers. In the first quarter of 2024, the CDC logged 58 cases across 17 states—matching the total number reported for all of 2023. International travel was linked to 93 % of those infections, with outbreaks simmering in places like Austria, the Philippines and the United Kingdom.

California alone has confirmed 59 cases as of August 31, 2024, a figure that includes the state’s first Napa County case since 2012 and a handful of exposures tied to public venues such as a restaurant in Alameda County and an LAX‑area cluster in Los Angeles County.

In the East Bay, Contra Costa Health Services warned residents about a measles case identified in late 2025. The infected individual shopped at several stores—including Macy’s, Anthropologie and the Apple Store—in Lafayette and Walnut Creek while contagious, underscoring how easily the virus can slip through everyday life.

The CDC still recommends two doses of the MMR vaccine: the first between 12‑15 months of age and the second between 4‑6 years, or before school starts. For kids traveling abroad, an extra dose as early as six months may be advised.

Why does this matter? Measles is outrageously contagious—about nine out of ten unvaccinated people exposed will get sick. It spreads through droplets that linger in the air and on surfaces for up to two hours. Early signs mimic a bad cold: fever, cough, runny nose and pink eye, followed by the classic rash about two weeks after exposure.

Public‑health officials encourage families to check their county health department’s website for the latest exposure notices and to keep immunization records up to date. The study’s authors hope that shining a light on these low‑coverage pockets will spark targeted outreach and, ultimately, close the gaps before an outbreak takes hold.