Measles Outbreak Worsens at Pilsen Migrant Shelter, Prompting Officials to Tighten Vaccination Policy

The former industrial building at 2241 S. Halsted St. that has been converted into the city's largest shelter. (WTTW News)The former industrial building at 2241 S. Halsted St. that has been converted into the city's largest shelter. (WTTW News)

Chicago health officials have confirmed 14 cases of measles in the past seven days, prompting them to tighten rules requiring all residents of the city’s largest migrant shelter to be vaccinated against the highly infectious disease.

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Twice in the past week, Chicago Department of Health officials have confirmed six cases of measles in a single day, the most since the apparent outbreak began on March 4. Nearly 70% of the cases are in children younger than 4, according to city data.

In all, 31 Chicagoans have been diagnosed with measles since March 4.

Andy Buchanan, a spokesperson for the agency known as CDPH, said the majority of the newly confirmed cases of measles are associated with the Pilsen migrant shelter, but declined to provide WTTW News with more detailed information. That represents a change since the first case of measles was confirmed in Chicago earlier this month.

“Due to patient privacy concerns, CDPH won’t be providing information about individual cases or suspected cases of measles unless there is a clear public health need in doing so,” Buchanan said in a statement.

There were 1,462 men, women and children living in the former industrial building at 2241 S. Halsted St. as of Friday, according to city data. Even though the shelter’s population has dropped by nearly 30% since the first confirmed case of measles was diagnosed, it remains the city’s largest migrant shelter.

City health officials said they have vaccinated more than 4,500 Chicagoans since the beginning of March. The two-dose measles-mumps-rubella vaccine, or the MMR vaccine, is highly effective and remains the best protection against measles.

The increase in measles cases is concentrated among young children at the Pilsen migrant shelter who recently received a single-dose MMR vaccine, according to a statement from CDPH officials.

A new policy will require all residents of the shelter to receive a second measles vaccine dose 28 days after the first dose, officials said.

“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 (the vaccine),” according to a statement.

The two doses of the vaccine are given at least 28 days apart, according to medical rules.

Families with children between the ages of 1 and 5 are being asked to keep their children home from child care 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, officials said.

A 5-year-old boy, Jean Carlos Martinez Rivero, who had been living with his family at the Pilsen shelter, died Dec. 17 after living at the shelter for several weeks with his family. His death was caused by sepsis and other viruses, including COVID-19, adenovirus and rhinovirus/enterovirus, according to an autopsy.

Mayor Brandon Johnson’s administration received complaints about unsanitary and unsafe conditions at the Pilsen migrant shelter as early as late October, more than a month before the 5-year-old boy’s death focused attention on the state of the facility, according to emails first reported by WTTW News.

Measles is a serious respiratory infection that is capable of leading to pneumonia and other complications. Symptoms of measles include rash, high fever, cough, runny nose and red, watery eyes and can take from seven to 21 days to show up after exposure. Measles can be dangerous to those who are unvaccinated, especially babies and young children.

In 2024, Illinois health officials confirmed five cases of measles outside of Chicago.

Contact Heather Cherone: @HeatherCherone | (773) 569-1863 | [email protected]

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