(NewsNation) — A young child at a Chicago shelter where more than 1,800 migrants are being housed is among the first two measles cases reported in the city since 2019, local health officials said Friday.

The Chicago Department of Public Health said a confirmed case of measles was identified in a resident at a new arrivals shelter. Health officials said the case was identified in a young child who has recovered and is no longer infectious.

However, Chicago Alderperson Byron Sigcho-Lopez, who represents the neighborhood where the shelter is located, said the bigger issue now becomes who may have been exposed. Sigcho-Lopez said that as of this week, the shelter had 1,876 residents, including 95 toddlers between the ages of 1 and 2.

The alderman said the shelter had previously had 2,550 migrants earlier this year. Sigcho-Lopez told NewsNation on Friday that conditions at the shelter in Chicago’s Pilsen neighborhood have been improving as its population has dropped.

But the health emergency that the alderman said he learned of Thursday night has now created new concerns.

“Right now, with this potential exposure to a rapidly spreading virus such as measles, it’s critical to have an isolation plan,” Sigcho-Lopez told NewsNation on Friday. “People need to be in isolation while they are being tested and will learn more of the assessment while people are sheltering in place, and we will wait for the results of the tests.”

Chicago city health officials are asking all shelter residents to remain in place until it can be determined whether migrants are vaccinated against measles and immune to the infectious disease. Sigcho-Lopez said that those who are vaccinated will be permitted to continue with their daily routines, but those who have not been vaccinated must remain indoors and watch for symptoms.

Chicago Public Schools officials confirmed that the child was not of school age and told parents that the city health department had told families at the shelter not to send their children to school Friday.

In an email to parents, school officials said that they would be on the lookout for students from the shelter who were accompanied by a parent. Those parents would be told that their child would not be permitted to attend classes.

The city began assessing the vaccination status of all residents Friday. Sigcho-Lopez said he is working with city health officials to better assess the situation. He visited the shelter Tuesday and plans to do so again once health officials have cleared him.   

He is uncertain of how long the assessment of the shelter population’s vaccination status will take. The shelter is the same facility where a 5-year-old Venezuelan boy died in mid-December.

Sigcho-Lopez said that he expects the shelter’s population to continue to decrease as families are provided with opportunities to move off-site. Mayor Brandon Johnson has twice pushed back shelter evictions, and new arrivals are scheduled to be moved out of temporary housing March 16.

In the meantime, though, Sigcho-Lopez said that health navigators who have visited the shelter have been talking with new arrivals about vaccine hesitancy. He said that the local community has dealt with that issue after receiving “misinformation” during the COVID-19 pandemic.

He said he has asked state officials to expedite health screenings for migrants once they arrive at the landing zone after being bused from Texas. But so far, progress on getting new arrivals access to proper health screenings and vaccinations — especially for children — has been slow.

“This is, unfortunately, a process that is too long when you have 1,800 people (in the shelter),” Sigcho-Lopez said Friday. “I recognize the process that has been made, but given how quickly this virus is spreading, we need to get people isolated.

“I think what we want from the governor is the commitment to better protocols so we can work toward better conditions and prevent cases like this.”