Predicting an outbreak

Where will the next measles outbreak strike? Chicago, LA and Miami beware

A new study ranks the threat in U.S. counties based on the number of unvaccinated individuals and the relative distance to international airports.


Chicago, Miami and Los Angeles are the U.S. cities most likely to see the next measles outbreaks, according to a new study.

Researchers at Johns Hopkins University and the University of Texas at Austin mapped the 25 American counties most at risk of measles due to their vaccine-exemption rates and proximity to large, international airports. The study, published in The Lancet Infectious Diseases, found that Cook County in Illinois, where Chicago is located, had the highest risk of a measles outbreak, followed by Los Angeles County in California and Miami-Dade County in Florida.

Here is a look at the 25 counties with the highest risk of a measles outbreak, according to the research.

Measles cases in 2019

According to the Centers for Disease Control and Prevention (CDC) and various state health departments, at least 45 counties have reported measles cases in 2019 and 30 of those are either included in the top 25 at-risk counties identified in the study, or are adjacent to one of the top 25 counties.

“Our results correctly predicted the areas in Washington, Oregon, and New York that have had major measles outbreaks. Brooklyn, New York, which has reported over 300 cases, is adjacent to Queens, New York, which ranked fourth. Multnomah, Oregon is ranked 13th, and adjacent to Clark, Washington with 73 cases,” the study notes.

The global threat of measles

After being declared eliminated in the U.S. in 2000, the CDC this week reported a total of 839 individual cases of measles across 23 states so far this year. This compares with 372 reported cases in 2018, 120 in 2017, 86 in 2016, 188 in 2015 and 667 in 2014.

The highly contagious disease is returning to communities with low vaccination rates fueled by non-medical exemptions (NMEs) where the virus is being reintroduced through travel from countries such as India, China, Ukraine and the Philippines, where large measles outbreaks are occurring, the report finds.

Measles remains a common disease in many parts of the world, according to the CDC, with an estimated 10 million people getting the disease each year. About 110,000 of them die from it.

A detailed description of the data and methods used for the study’s predictions are available here.

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