The Illinois Department of Public Health has declared the Southern Illinois measles outbreak over. There were eight total cases that were all linked to one another in April and May in the Williamson County area, but no new cases since May 22nd.
There were two unrelated cases identified in the Chicago area around the same time. Those did not constitute an outbreak, and there was no further indication of any additional spread beyond those two individuals.
IDPH says immunizations against measles remains the best protection for children and adults. Rapid response from IDPH and local health departments kept the virus spread to a minimum and prevented additional cases.
The Illinois measles cases came as the nation is facing the largest number of cases nationwide since measles was officially eliminated from the U.S. in 2000. The Centers for Disease Control and Prevention (CDC) have reported the highest number of annual cases across the nation in 33 years– 1,288 confirmed cases across 39 jurisdictions in 2025 alone.
92% of cases have affected unvaccinated individuals or individuals whose vaccination status is unknown. There have been 3 deaths from measles in the U.S. this year, equaling the total measles deaths nationwide between 2001 and 2024.
Illinois Department of Public Health Director Dr. Sameer Vohra says the end of this outbreak, capping at just 8 cases and no serious illnesses in Illinois, is a testament to the deliberate, decisive, and successful work of our public health and medical professionals. He recommends that Illinois residents make sure that they and their family members are up to date on the measles/mumps/rubella vaccine and all other age-appropriate immunizations.
According to the CDC, one dose of measles/mumps/rubella (MMR) vaccine is 93% effective against measles, and two doses are 97% effective in protection from measles.
Measles is easily spread through the air when someone coughs or sneezes. Measles can cause serious and long-term complications, including pneumonia and brain infections, leading to long-term brain and nerve damage. Around one in five children under five years of age end up hospitalized with measles, where unvaccinated children experience severe illness or even death.
