CHICAGO – Due to increasing measles cases among young children at the Halsted Street shelter in Pilsen who recently received a single dose of the measles-mumps-rubella (MMR) vaccine, the City of Chicago announced Monday that everyone at the Halsted shelter should receive a second measles vaccine dose 28 days after the first dose. The policy will ensure the best protection for preschool children in particular until their immunity to measles is fully developed, and will prevent potential spread of the highly contagious virus to other preschool children that have not yet received a second dose of MMR. The City is asking families with children aged 1-5 years at the shelter to keep those children home from childcare and preschool until 21 days after they have received a second dose of the vaccine or 21 days after last exposure if the children cannot be vaccinated.  

Recommendations from the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) state that a second dose can be administered as soon as 28 days after the first. With the second dose of MMR, effectiveness increases to 97%. The State of Illinois requires two doses of MMR vaccine for K-12 school attendance; in response to this measles outbreak, this policy will be extended to children who are 5 years of age and younger. Shelter residents under 12 months who are not yet vaccinated must be excluded from daycare or early learning until 21 days after their last measles exposure.  

The updated vaccination schedule for residents of the Pilsen shelter who are experiencing exposure to confirmed measles cases and are aged 1-5 will be as follows: 

• 1st dose 
• wait 28 days 
• 2nd dose 
• wait 21 days    
• Return to preschool or daycare 

This new policy is expected to impact about 50 children 1-5 enrolled in school/early learning. Unless exempt for medical reasons, all eligible children at the shelter have received at least one dose already. Those who can provide proof of immunity (prior infection or 21 days post 2-dose regimen as of March 25) can attend school or day care.  

The Chicago Department of Public Health has worked with its many community and healthcare partners to mobilize vaccine operations at new arrival shelters and at the landing zone, and about 4,500 people have received the MMR vaccine since the first measles case was identified in the city. That operation will continue with administration of first doses for those who haven’t received one and second doses for those eligible. 

“While the MMR vaccine is the best protection against the virus, children are at highest risk for contracting breakthrough measles after receiving one dose of the vaccine, especially those less than 5 years old. We’re seeing some of these cases at the Halsted shelter, which isn’t surprising,” said CDPH Commissioner Olusimbo ‘Simbo’ Ige, MD, MPH. “I understand this will be a challenge for families, but we want to do everything to protect young children from contracting measles by ensuring 2 doses of the MMR vaccine .” 

Older school-age children are required to have received 2 doses of MMR and would be better protected from measles. The MMR vaccine is recommended at 12 months of age and a second dose at 4 to 6 years of age, but that second dose can be given as soon as 28 days after the first. 

To date, CDPH has identified 26 confirmed cases of measles in Chicago residents, the majority of which have been associated with Pilsen new arrivals shelter. Of the 26 confirmed cases, 19 are in children below the age of 5, underscoring the critical importance of the vaccine in fighting the spread of this disease in young children. 

CDPH now has an official measles dashboard on our website, updated every morning with the most recent measles data, including case numbers and age demographics. CDPH and the Office of Emergency Management and Communications are maintaining a standing presence at the City's Landing Zone, providing vaccination for measles to individuals as they arrive in Chicago. New arrivals are screened and directed to follow-up care with Cook County Health or other partner providers if needed, with the most emergent cases receiving top priority. All new arrivals who have been vaccinated or provide proof of vaccination will be placed into temporary shelters. 

The United States is currently experiencing a resurgence of measles, and cases have been reported in 17 states so far. Measles is a highly contagious and serious respiratory infection that causes a rash and high fever and is capable of leading to pneumonia and other complications and can be particularly challenging for babies and young children.  

All Chicagoans are encouraged to review their immunization records or contact their healthcare provider to make sure they are up to date on the MMR vaccine. Immunization records recorded in the Illinois immunization registry can be accessed using the Illinois Department of Public Health Vax Verify portal . 

MMR vaccine is available at most doctor’s offices and pharmacies. Illinois children as young as 7 years old can get vaccinated at pharmacies under Illinois law. CDPH Immunization clinics provide MMR vaccine for no out-of-pocket cost to any child 0–18 years and uninsured adults 19 and older. For more information on measles please visit the CDPH website. 

A first dose of the MMR vaccine is recommended at 12 months of age and a second at 4 to 6 years of age, but it is never too late to get your MMR vaccine if you haven't already. CDPH offers MMR vaccinations at no cost for uninsured adults and children eligible for the Vaccines For Children program at our various health clinics around Chicago. Adults who aren't sure if they're vaccinated against measles should contact their health care provider. For more information about measles and how you can protect yourself, visit the CDC website. 

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