US grapples with measles outbreaks. Is IL’s vaccination rate enough to avoid one?
As Texas, Kentucky, Ohio, Kansas and other states confront cases of a contagious and preventable disease, Illinois health officials are encouraging residents to get their children vaccinated.
While measles was declared eliminated in the U.S. in 2000, infections and outbreaks still occur, and the Illinois Department of Public Health reported 67 cases in the state in 2024. These cases were primarily related to an outbreak in Chicago, which ended in May 2024. No measles cases have been reported in Illinois so far this year, as of April 4.
The measles vaccine is called MMR and is designed to protect against measles, mumps and rubella. Illinois health officials recommend children receive the first dose at 12 to 15 months of age and a second dose at 4 to 6 years old.
Illinois’ statewide measles vaccination rate typically hovers around 95%, though the number may be dropping to closer to 93% with an increase in vaccine exemptions, Dr. Vidya Sundareshan, infectious diseases specialist at Southern Illinois University Medicine and medical advisor to Sangamon County Health Department, wrote in a March 19 email to the News-Democrat.
The measles vaccination rate for Illinois kindergartners in the 2023-24 school year was 91.6%, NBC News reported, based on U.S. Centers for Disease Control and Prevention data. This rate reflects the portion of children who have received two doses of the MMR vaccine.
“Herd immunity for measles is usually estimated at 92-94%,” Sundareshan wrote. “It is preferred to have vaccination rates greater than 95% as accumulation of clusters of under-vaccinated children can lead to outbreaks.”
Illinois Department of Public Health measles vaccination rate data for schoolchildren shows some Illinois schools do not meet the preferred 95% vaccination threshold for herd immunity, including Belle Valley School (with a 92.7% measles vaccination rate) and others.
How at-risk of measles are Illinois residents?
Illinois residents who have been vaccinated against measles are very likely to be protected against any outbreaks.
“MMR vaccine is the most important tool to prevent measles. It is nearly 100% effective in preventing measles in children who have received two doses of the vaccine,” Sundareshan wrote. “Measles can cause severe complications like pneumonia, encephalitis (inflammation of the brain) and death in some cases.”
The CDC reports one measles-related death has been confirmed in the U.S. so far in 2025, and another potential measles death is under investigation.
Older children and adults who did not receive the MMR vaccine at the recommended age can and should still get vaccinated, the CDC reports.
“Almost everyone who has not had the MMR vaccine will get sick if they are exposed to those viruses,” the CDC website says.
Some people should not receive the MMR vaccine or should wait to get it, however, including people who have had allergic reactions to the vaccine, people who are pregnant, people who have tuberculosis and some other populations. But overall, the vaccine is “is very safe and is effective.”
Additionally, while misinformation sometimes spreads about a potential link between vaccination and autism, the CDC reports there is no link between the MMR vaccine and autism.
One dose of the MMR vaccine is about 93% effective against measles, according to the CDC, while two doses are 97% effective.
Here’s how many measles cases were reported in Illinois in recent years, according to the state’s department of public health:
2025: 0 measles cases reported as of April 4
2024: 67
2023: 5
2022: 0
2021: 0
2020: 0
2019: 5
Prevention strategies such as vaccination are vital in avoiding potential outbreaks this spring and summer, Sundareshan said, and any cases need to be promptly isolated and reported to public health officials.
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