Illinois is facing an increasing risk of measles outbreaks as vaccination rates in some schools fall below the critical 95 herd immunity threshold. This comes at a time when neighboring states are experiencing rising cases, raising alarm among public health officials. Health experts warn that the situation is particularly concerning in areas with low vaccination coverage, which could lead to larger, more widespread outbreaks in the coming months.
Rising Concern Amid Lower Vaccination Rates
In early 2025, Illinois public health officials are on high alert due to the alarming drop in measles vaccination rates across the state, especially in schools. The Illinois Department of Public Health IDPH has reported that vaccination rates in several regions of the state are dangerously low, with some schools dipping well below the 95 threshold required for herd immunity. The situation is compounded by the fact that neighboring states, such as Indiana, have already seen a surge in measles cases, prompting fears that the virus could cross state lines into Illinois.
Dr. Sameer Vohra, Illinois Director of Public Health, highlighted the growing risk: Its really worrying, he said. Were seeing cases in states around us, and theres no doubt it could be coming to Illinois.
Illinois vulnerability was made clear when the state saw its largest measles outbreak in 30 years in 2024, with 67 cases traced to a migrant shelter. While the outbreak was contained within a few months, the increase in measles cases across the U.S. at the beginning of 2025 signals that Illinois is at risk of further outbreaks if vaccination rates do not improve.
Measles Dashboard for Transparency and Action
To address the growing concerns, Illinois launched a new Measles Outbreak Simulator Dashboard in early 2025. This tool allows parents, guardians, and school officials to check the vaccination rates at specific schools across the state. The dashboard provides a clear picture of the potential risk of measles outbreaks based on vaccination data from the 20232024 school year, allowing families to make informed decisions about vaccination.
The dashboard also allows users to simulate potential outbreaks, offering projections based on current vaccination rates and school enrollment data. Health experts emphasize that ensuring all children are vaccinated with the recommended two doses of the measles, mumps, and rubella MMR vaccine is key to preventing an outbreak. With one dose of the MMR vaccine 93 effective and two doses providing 97 protection, vaccination remains the most effective method of prevention.
Measles is highly contagious, Dr. Vohra said. If vaccination rates dont improve, we are at risk of seeing more cases, and it could spread quickly through schools and communities.
The Local Impact and Risk Areas
While most Illinois residents are still protected against measles due to childhood vaccinations, areas with lower vaccination rates are particularly vulnerable. Data from the IDPH shows several counties and districts with significantly lower vaccination rates, especially in the southern parts of the state. For example, Pope County had a measles vaccination rate of just 78.4, and nearby Massac County recorded 89.6.
Even in more densely populated areas like Cook County, where the vaccination rate averages 96.5, there are pockets of lower vaccination coverage that could lead to localized outbreaks. Chicago Public Schools CPS data reveals that vaccination rates in some schools are below the herd immunity threshold, with one school, Brennemann Elementary, reporting just 60.1 vaccination coverage. While CPS officials maintain that their internal numbers are higher, with 95.6 of students vaccinated, the states dashboard highlights a significant concern regarding the uneven distribution of vaccinations across the district.
Were making progress, but theres still work to be done, said Dr. Vohra. Some schools are doing well, but others still need to improve.
National Context and Lessons Learned
Illinois is not alone in its struggles with measles vaccination. The ongoing outbreaks in other parts of the United States, particularly in states like Indiana, where six new cases were reported in early 2025, have only heightened concerns. Four of these cases were in unvaccinated children, underscoring the importance of vaccination in preventing outbreaks.
Measles spreads easily through the air when someone coughs or sneezes, said Dr. Vohra. It can cause serious, longterm complications, such as pneumonia and swelling of the brain, especially in unvaccinated individuals.
The lessons learned from Illinois own 2024 outbreak have led to better preparedness and a more coordinated public health response. Officials emphasize that with the right tools, including the new simulator dashboard, the state can manage and potentially prevent further outbreaks. However, this requires a concerted effort from parents, schools, and public health agencies to ensure that vaccination rates are consistently high.
Moving Forward: What Can Be Done?
Public health officials in Illinois are urging families to get their children vaccinated as soon as possible, particularly those who are not uptodate with their MMR vaccines. Dr. Vohra stressed that while the state has not seen a confirmed measles case since early 2024, the risk remains high. We cannot afford to be complacent, he said. Vaccination is the best defense we have against this highly contagious disease.
Illinois has also committed to improving vaccination coverage in schools, especially in areas with low rates. The IDPH is working closely with school administrators to ensure that vaccination rates are regularly monitored and that parents are aware of the risks of not vaccinating their children.
In conclusion, as measles cases rise across the country, Illinois must focus on maintaining high vaccination rates to protect its residents, especially vulnerable populations. With tools like the Measles Outbreak Simulator Dashboard, the state is better equipped to prevent and manage future outbreaks, but this will require continued vigilance and cooperation from all levels of society.