With concerns that Thanksgiving gatherings could produce a surge on top of a surge of COVID-19 cases, Illinois won’t be moving from Tier 3 COVID-19 restrictions for at least the next few weeks, Gov. JB Pritzker said Monday.

While cases have dropped, hospitalizations remain highest since the spring surge, Pritzker said.

“If we are not especially careful right now, the surge will overwhelm our health care system,” Pritzker said in explaining why he intends to keep restrictions in place, even if cases continue to decrease in the short-term.

The state’s public health director, Dr. Ngozi Ezike, also recommended that anyone who got together with people outside of their immediate family for Thanksgiving get tested for the virus six or seven days after they spent time with others, saying that could help identify any COVID-19 spread.

Illinois public health officials reported 6,190 more probable and confirmed cases of COVID-19 in the past 24 hours and 85 more people have died of the virus. Officials also say more than 5,849 people were in the hospital with COVID-19 as of Sunday night.  

But what do the COVID-19 numbers actually tell us about how effective the measures have been so far? Furthermore, what can Illinois expect from this holiday season?

We took those questions to experts at Northwestern and University of Chicago Medical Centers.

Are the restrictions having an effect?

We don’t know yet.

Today’s positive test results are really a snapshot from COVID-19 cases contracted an average of seven days before.

Pritzker noted Monday that the downward trend in case counts in the past week are not from Tier 3 restrictions — which are from 10 days ago — but rather more likely from the restrictions and adherence from weeks before.

The state shut down indoor dining and bars in much of the state around Oct. 30. Tier 3 restrictions went into effect Nov. 20, and cases have gone down in both Chicago and Illinois as a whole.

On Nov. 20, Illinois reported 12,954 new probable and confirmed cases of COVID-19. Over the past week, the state has averaged 8,812 cases a day. That’s a more than 20% decrease from the week prior.

What explains that drop? Again, it’s unclear.

Epidemiologists say that the most recent drop may be more about testing than cases.

Over the weekend, fewer people were tested for COVID-19 in Illinois than in the week prior, which could potentially contribute to the decline in positive cases we’re seeing right now. The Thanksgiving holiday also fell on a weekend, which means that test results can be delayed a bit.

On top of that, to give healthcare workers a break, some testing centers were also closed.

University of Chicago Hospital epidemiologist Emily Landon said the push of restrictions against the pull of holiday gatherings make it even more difficult to understand what exactly is happening right now.

“I know that people are thrilled to see the numbers going down a little bit, and would like to see us stop some of the mitigations now, but I don’t think that’s a good idea,” she said. “You have to keep doing them for longer than you’d think you have to.”

Understand that the state’s numbers are merely a sketch of the pandemic situation at any given time. Doctors said that hospitalization rates tell you more about how serious the pandemic is, which Pritzker alluded to Monday.

An average of 5,944 people have been in the hospital for COVID-19 during the last seven days. Those people caught the virus within the last two to three weeks, on average.

Will Thanksgiving affect the numbers?

Experts say yes, but don’t know how much yet.

Beating back COVID-19 is like stopping a tidal wave, Landon said. You can’t — you can only slow it — and the goal is to use restrictions to break the surge a little at a time.

We’ll know in about seven to 10 days what the initial wave of infections looks like. But it will take three to four weeks to understand the holiday’s full impact. It’s more than just the people who were infected at a Thanksgiving gathering — it’s a potential exponential spread of the virus.

“Any one transmission event is not the real problem,” Landon said. “It’s that those people then go out and infect two more people and those people go out and infect two more people. After two or three incubation periods, you have a massive outbreak.”

Landon hopes that the Tier 3 mitigations put in place before Thanksgiving could have led to fewer people being exposed to COVID-19 ahead of the holiday. Those same restrictions could then limit someone who was infected at a gathering from spreading the virus throughout the community.

It’s hard to say exactly how many people traveled and how many stayed home in Illinois. AAA estimated that 2.4 million people in Illinois were expected to travel over the Thanksgiving holiday, but that number could be lower as people monitored COVID-19 cases.

Nationally, CNN reports that 9.4 million people flew between the Friday before Thanksgiving and Sunday. That’s an all time high during the pandemic.

We don’t know how many people attended unmasked gatherings, which is the real issue.

Lori Post is a professor of emergency medicine at Northwestern University who closely surveils COVID-19 data. She is expecting a “God awful” upward spike in cases about a week from now. There’s quite a few risk factors at play as the pandemic is accelerating all across the country.

Emissions data shows that people are moving around more now than they were during spring lockdowns, and activities once considered nonessential are commonplace.

Not only are people travelling for the holiday, many students were sent home from college the rest of the year, because universities didn’t want them bringing COVID-19 back to campus, Post said. They’re more likely to be asymptomatic and infect older, less healthy relatives.

Statistically, the United States also has higher incidences of COVID-19 risk factors like heart disease, hypertension and diabetes, compared to other countries.

And in the spring, during the last peak, the virus was less prevalent outside of large urban areas. Now it’s everywhere, Post said.

Post, who is from Oklahoma, compared the dip in case numbers in the state to the calm before a tornado.

“Right before a tornado touches down — everything is still,” she said. “That’s where we’re at right now, and we’re about ready to go for a really big ride here.”

What can the state expect from the upcoming holiday season?

Epidemiologists can’t project that far.

If people gather unmasked again for Christmas, Hanukkah or New Year’s, there will obviously be more COVID-19 spread. But science is not divination — there is literally no model that can tell us what the pandemic will look like a month from now.

However, hospitals are seriously concerned about capacity. There’s not much slack in the medical system, so a serious influx in cases can put lives in jeopardy.

Marc Sala is a pulmonologist at Northwestern Memorial Hospital. Part of his job is managing ventilators for patients with COVID-19.

Right now, the hospital is not at capacity, but Sala said the tension doctors feel resembles the very beginning of the pandemic.

“It’s just a question of when the numbers will dramatically increase,” he said. “It’s just an uncertainty of how much.”

He said with the limited data we have, it’s very difficult to know how bad the wave will hit hospitals like his. He said their eyes are always on the number of ventilators and beds available.

“We fear what will come from the winter holidays,” he said. “We’ve seen numbers go up with this most recent surge over the last month. What we really don’t want to have happen is a punctuated onslaught of new cases in the next week.”

Vivian McCall is a news intern at WBEZ. Follow her @MVivianMcCall.