Chicago measles outbreak: 41 cases to date
In a follow-up on the measles outbreak in Chicago, the Chicago Department of Public Health (CDPH) reports 41 measles cases through March 28, which include 13 cases reported just this week so far.
Case counts include Chicago residents diagnosed with measles in 2024, and non-Chicago residents associated with the Chicago-based measles outbreak.
More than two-thirds of the cases (68%) are in children 0-4 years of age.
On Monday, health officials had 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.
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. Â
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. Â
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.Â
Two other cases have been reported in Illinois with one case each in Lake County and Will County.
The United States is currently experiencing a resurgence of measles, and 64 cases have been reported in 17 states as of March 21.
In all of 2023, a total of 58 measles cases were reported by 20 jurisdictions.