Officials had planned this week to announce some reopening guidelines for Chicago, but that's been put on hold amid worries about a potential third surge.
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The city looks at case numbers, test positivity, emergency room visits for COVID and ICU cases for the disease. All except ICUs are on the upswing, and the city says the data looks like it did in mid-December.
The rise in infections is being driven by young adults 18 to 29, pushing the city's test positivity rate to 3.2% - half a point higher than it was two weeks ago.
WATCH | Chicago COVID cases rising among young adults
"Even if there are more cases in young people, we still are seeing that translate into it an increase in hospitalizations," Arwady said. "I am concerned, and I hope everybody is concerned when they look at this data."
Chicago is now averaging 360 daily cases, well above the target of less than 200 and approaching the "high risk" threshold of 400 cases per day.
More people also seeking treatment, with emergency department visits up 45% in the last two weeks.
"These sorts of increases are just what we were seeing in October," Arwady said.
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"This could turn out to be a bunny hill for us in Chicago, with us in Illinois, or it could turn out to be a triple black diamond slope if we're not careful," said Dr. Emily Landon, an infectious disease specialist at University of Chicago Medicine. "It's all about how we behave."
Arwady said Michigan's situation is a harbinger of tougher times that could revisit Chicago. She says the neighboring state was doing a good job testing for and managing COVID-19, but now sports the third highest number of cases in the country.
Michigan has been hit particularly hard by the UK variant, something she says is afoot in Chicago.
"It is a problem here," Arwady said. "We are up 30% in cases just in the past 14 days and up 23% in the last week, so we're not talking about the greater than 100% that they have seen in Michigan, nevertheless, right now, not headed the right way."
As drive-thru vaccinations begin at the United Center and more providers come online, federal vaccine deliveries are ramping up.
Next week, Illinois and Chicago together are set to receive 22% more doses compared to this week.
Johnson & Johnson deliveries are increasing to 74,000, up from less than 15,000 this week.
But the promising news is tempered by those rising case numbers.
"I'm very concerned, Eric," said Dr. Ngozi Ezike, director, Illinois Dept. of Public Health. "As good as the news is that we have three different vaccines, and we've given millions of doses, we're not out of the woods yet."
If cases continue to rise, it could delay the state's reopening, which is dependent on increasing vaccinations but also stable health and hospital numbers.
"If you are taking some chances with COVID, please rethink that," Arwady urged. "Please wear your mask and please be extra careful if you are interacting with anyone who is older or anybody with an underlying condition."