Researchers have been warning us for some time that vaccination rates were dipping dangerously low. Non-medical vaccine exemptions have been rising in most of the 18 states that allow them, and some areas were forming pockets of un-immunized children who would be susceptible to viruses like measles.
One team in particular, at Baylor College of Medicine, went so far as to analyze which counties would be most likely to experience these outbreaks. They published the list, along with other analyses, in PLoS Medicine last June. It contained 14 counties—and so far three of them have had outbreaks. And the current outbreaks not on their list are largely being driven by Orthodox Jewish communities.
If you happen to be familiar with county names (or are just very good at geography), you might notice that these are all counties with cities in them. That’s intentional. “We looked at the data in two ways, first just by percentage of vaccine exemptions, which was the first map,” explains Peter Hotez, Dean of the National School of Tropical Medicine at Baylor and an expert in pediatric vaccinations who co-wrote the study. “But we noticed that was primarily showing rural areas, like Idaho, and we wanted some way to represent urban areas where there were large number of kids at risk.” They originally figured they’d look at roughly the top dozen urban counties, which ended up being those counties that had 400 or more kindergarteners with exemptions.