New Study Pinpoints Under-Immunization Hotspots in Northern California

As California’s recent measles outbreak continues in earnest, a new study by Kaiser has identified several geographic areas in Northern California where people remain under-immunized.

According to the study, published in the "Pediatrics" medical journal, 17.5% of children lack at least one of 17 recommended vaccines in parts of Sonoma and Napa Counties. Clusters of under-immunization were also found in the East Bay from Richmond to San Leandro, an area between Sacramento and Roseville, northern San Francisco, southern Marin county, and part of Vallejo. The study further identified five clusters with especially high vaccination refusal rates. Those refusals, experts say, make the population especially vulnerable to widespread illness.

“I think there’s really strong evidence that areas where there are high under-immunization, there is a higher risk of disease outbreak,” said the study’s lead author, Tracy A. Lieu. However, she added, "To the extent that we can identify these hot spots early on, it may help us to identify emerging epidemics sooner.”

The results were based on an analysis of electronic medical records belonging to Kaiser patients, including those of 154,424 children who were born between 2000 and 2011.

Read more about the study here.