CHICAGO (NewsNation) — A total of 17 confirmed measles cases have been reported in Chicago as of Friday, the majority of which are at the city’s largest migrant shelter , according to city health officials.

Of the cases found among city residents, 11 of the 17 involve children under the age of 5, the Chicago Department of Public Health announced.

The new cases come a week after a modified version of Mayor Brandon Johnson’s 60-day shelter exit plan required that all migrants living in city-run shelters be vaccinated against measles.

City officials said last week that due to the outbreak, the more than 1,800 residents at the Halsted Street shelter in Chicago’s Pilsen neighborhood are exempt from being evicted from the facility regardless of how long migrants have been in place.

The update from the city health department is the first since the agency reported that 10 cases had been confirmed at the shelter as of last week. The first confirmed case at the shelter was announced on March 10, when local leaders and health experts predicted that the number of cases would only keep growing.

The mayor’s office said last week that the average stay is 94 days. Evictions from shelters began last weekend when only three of 34 migrants scheduled to depart city-run housing actually did.

A coalition of city council members have pushed Johnson to end his 60-day policy. However, this week, Johnson said that the city can only do so much given the “restraints” it faces.

“I’ve said from the very beginning that this mission is not sustainable,” Johnson said at a news conference this week. “Local municipalities are not designed to deal with an international global crisis, particularly as it relates to migrants and asylum seekers, and it’s never been designed to do that.”

Chicago Department of Public Health Commissioner Olusimbo “Simbo” Ige said last week that health officials are working to get 95% of residents at select shelters vaccinated against measles. She said that the Halsted shelter had already reached that threshold after the city vaccinated more than 900 residents at the facility vaccinated in two days after the first case was announced.

Another 700 shelter residents had either already been vaccinated or had previously had measles, making them exempt. However, after some shelter residents complained about inhumane living conditions at the Pilsen shelter, health officials announced that those who needed to quarantine would be moved to local hotels or other shelters with more space.

Ige said last week that no migrants or asylum seekers have refused the vaccine under the new shelter requirement. Three shelters, including the Halsed facility, have reached the 95% vaccine threshold and Ige said city health officials will begin prioritizing more shelters to try to limit the spread of measles.

A team from the Centers For Disease Control and Prevention was sent to Chicago in the early stage of the outbreak to assist city health officials.