Elementary schools in the inner-city Los Angeles neighborhood of Compton have a far higher vaccination rate against diseases like measles than schools in wealthy Beverly Hills, state data show.

The rate in Compton is 93.80%, near the 2013-14 national median of 94.7%, with one school at 100%. In Beverly Hills elementary schools, the rate is a mere 78.33%, creating the conditions for an outbreak.

The level in Beverly Hills falls well below “herd immunity“–the minimum level, usually 90-95%, past which an entire population may be considered immune from a disease even if a few individuals are not themselves immunized.

The disparity in data follows a trend across the state, where the wealthiest communities are among those with the lowest rates of immunization. One expert who has studied the problem has joked that the way to find under-vaccinated areas is to “take a map and put a pin wherever there’s a Whole Foods.” Some poor communities are also highly under-immunized.

Though the mainstream media have covered the vaccination controversy as if it were a Republican problem, owing to recent comments by GOP presidential contenders, liberals are slightly more likely to resist vaccination than conservatives.

Data on vaccination are publicly available from the California Department of Public Health, but have also recently been compiled by several news organizations, in this case the San Jose Mercury News, for ease of public research.

Senior Editor-at-Large Joel B. Pollak edits Breitbart California and is the author of the new ebook, Wacko Birds: The Fall (and Rise) of the Tea Party, available for Amazon Kindle.

Follow Joel on Twitter: @joelpollak