Chicago is beginning to initiate a proof-of-vaccination policy for indoor venues as it looks to avoid another lockdown to fight COVID-19 amidst a surge in cases, Mayor Lori Lightfoot said on Monday.

In an interview with CNBC, the mayor of one of the most populated U.S. cities said that the new policy is aimed at encouraging individuals to get vaccinated and address what her office called an “alarming” rise in cases in December. Lightfoot explained that the number of unvaccinated people in ICU beds at Chicago hospitals underlined the need for more vaccinations.

“What we’re seeing is the overwhelming majority of people that are in non-ICU beds, ICU beds, and unfortunately, who are dying are the unvaccinated,” Lightfoot told CNBC. “It’s not even a close call.”

Under this policy, places like bars, restaurants and gyms would require proof of vaccination for entry. Lightfoot said that by making it a requirement to get vaccinated to use these facilities, she hoped to change minds of those currently on the fence about getting a shot.

Case numbers for COVID-19 shot up dramatically in the last month across Chicago, according to city data. Hospitalizations and deaths have not gone up to the same degree, but they have inched higher while the overall daily positivity rate as of Thursday was 17.2%, more than double the rate recorded only a week earlier.

The winter surge has raised fears across the country that the U.S. could fall into another lockdown if the rise in cases is not slowed. President Joe Biden said he is not planning to order another national lockdown in November after the Omicron variant was first detected, but cautioned that he was not ruling anything out completely.

Lightfoot expressed similar sentiments.

“Look, my goal is to make sure we never shut down again,” said Lightfoot. "If we have to do that, certainly I’m not going to take that off the table, but my goal is that we never get to that place.”

Lightfoot’s statements also come at a time when the city is squaring up for a clash with the teacher’s union over the return to in-person learning with a new school semester beginning.

On Tuesday, the Chicago Teachers Union (CTU) is set to vote on whether or not they support working remotely instead of in-person instruction when the semester starts on Wednesday. The union previously called on the Chicago Public Schools system to allow the first two weeks of learning to be remote as demanded by schools elsewhere like New York City.

Lightfoot waved off the opposition from the CTU as “saber-rattling” and dismissed remote learning as more harmful to children than returning to school. She asserted that schools were not a source of “significant spread” in Chicago.

“We need to keep our kids in school, which is what we’re going to do in Chicago,” she said.