IDPH Declares Measles Outbreak in Northeast Illinois is Over with No New Cases Since Mid-April

Cooperation among State of Illinois, Chicago, Suburban Cook, DuPage, Lake and Will Counties helped to rapidly contain the 2024 outbreak

CHICAGO – The Illinois Department of Public Health (IDPH) announced that the largest measles outbreak to affect the state of Illinois since 1990 is officially contained as no new cases have been reported for more than 42 days, two full incubation periods. A total of 67 measles cases were reported during the outbreak, which started March 7, with the vast majority linked to a Chicago shelter for new arrivals. Cases eventually extended beyond Chicago to suburban Cook County, DuPage, Lake and Will counties, but were rapidly contained in all these other locations.

“I applaud all of the public health, health care, emergency management and social service staffers who worked so diligently to cooperate across jurisdictional lines to contain this measles outbreak,” said IDPH Director Dr. Sameer Vohra. “Public health is a team sport founded on partnership, and this was no better exemplified than during this recent outbreak. Vaccination remains our most effective tool to prevent future outbreaks. Please reach out to your primary care provider this summer to ensure that you are up to date on the MMR vaccine and all other routine immunizations.”  

Throughout the outbreak, IDPH, the Illinois Department of Human Services (DHS), and Illinois Emergency Management Agency (IEMA) mobilized resources to support local public health partners, starting with the Chicago Department of Public Health (CDPH). The state also provided epidemiological support for county public health departments for Cook, DuPage, Lake and Will counties.

IDPH Director Vohra extended his thanks on behalf of the State of Illinois to CDPH and the other local public health partners as well as the hospital systems that responded so quickly and effectively to the crisis.

Early in the outbreak, IDPH activated Emerging Diseases funding to support a DHS-run quarantine hotel-shelter in Chicago that allowed for the most vulnerable new arrivals (pregnant and immunocompromised people and young children) to quarantine safely while also helping decompress the shelter with the largest outbreak.

IDPH also expanded its laboratory capacity to expedite measles testing and provided results back faster than any commercial lab. State and local partners convened educational and awareness sessions with clinicians, community leaders and school personnel which led to increased vaccinations, testing and rapid reporting of cases. In addition, the state galvanized its public service sector through DHS to assist with contact tracing of those who had left the shelter system and re-organized mass events such as job fairs to minimize the risk of super-spreader events. 

Through effective leadership and collaboration, the IDPH vaccine team augmented the vaccine supply needed in the City of Chicago and expedited identification of vaccination records for new arrivals attending schools. A school vaccine dashboard was developed to help local jurisdictions guide decisions on need for enhanced vaccinations in schools.

The state also provided on-site clinical and infection prevention support, including medical screening and triage assistance at the shelters and infection control assessments at quarantine sites. State officials convened multiple leadership meetings with stakeholders to identify solutions for isolation (for people already infected with measles) in addition to quarantine (for people only exposed to measles). The state is continuing to work with its local partners to refine these options in anticipation of greater need in the future.

Most residents of Chicago and Illinois were vaccinated for measles routinely in childhood and therefore were not at risk during the outbreak.

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. The CDC reports that as of the end of May, there were a total of 146 measles cases reported in 21 jurisdictions around the U.S. suggesting an ongoing need for continued vigilance and vaccination against measles, especially for unvaccinated children and adults. 

IDPH stresses the importance of ensuring everyone in your family is up to date on their immunizations. Since the COVID-19 pandemic, vaccination rates in the United States have dropped, increasing the likelihood of more cases of vaccine-preventable diseases. Individuals can protect themselves and their communities by doing their part and ensuring their families are up to date on all recommended vaccines.

More information about the Illinois outbreak is available by clicking HERE.