A Sun-Times analysis of state data found the rate of vaccinations has dropped sharply from the rate in 2019, when 90% of schools were at herd immunity.

New analysis of data from the Illinois Board of Education found less than half of Chicago Public Schools had herd immunity against the measles.

Measles cases surge in the U.S., with outbreaks across 31 jurisdictions. Experts warn of the virus's contagiousness and call for vaccination.

Measles cases have shown up in different parts of Illinois. While the outbreaks have been smaller than what some states are experiencing, many residents — including parents — are worried about the risks.

As of May 8, the U.S. has logged more more than 1,000 measles cases across 31 states — compared to 285 cases in all of 2024.

Millions of Americans live with immune issues and depend on herd immunity to protect them from contagious diseases like measles.

North America has two other ongoing outbreaks, all of which are the same measles strain. One outbreak in Ontario, Canada, has resulted in 1,440 cases from mid-October through May 6, up 197 cases in a week. And the Mexican state of Chihuahua had 1,041 measles cases and one death as of Friday, according to data from the state health ministry.

Americans worry about the Trump administration's ability to contain an ongoing outbreak of measles, while the vast majority of them believe that vaccines for the disease are safe, according to a new Reuters/Ipsos poll.