A COVID-19 surge in your county? New Illinois website offers ways to check.
Wednesday, July 01, 2020
by Joe Mahr
As Illinois shifts into phase four of its reopening plan, state health officials have now made it possible for residents to track weekly COVID-19 figures at the county level.
Their new website includes a warning system to highlight instances where the latest numbers — such as a rise in cases or more people testing positive — signal trouble.
Score poorly overall and the county will show up as orange on a blue map of the state. (Only one has qualified thus far. More on that in a moment.)
“If your county is colored orange, that’s a caution or a warning that something is going on,” the department’s director, Dr. Ngozi Ezike, said last week at a briefing with reporters. “And our goal is that, with that caution, you will think twice of your own personal habits and activities.”
The Illinois Department of Public Health unveiled the site just before the state on Friday officially entered the latest phase of its reopening plan, which allows people more freedom to gather and move about.
So far, Illinois officials have said, new case counts remain relatively flat and the state has plenty of available ICU beds and ventilators. But that could change. In other states, rises in cases have led to tightened restrictions as hospitals fill up.
“The metrics that we’ve been watching all along, to move us forward in our phases, are the very same metrics that we’re watching about whether or not we need to think about moving backward,” said Gov. J.B. Pritzker said last week.
Researchers who work with the state on pandemic modeling say the new display of data is good but not perfect. The information can be a week old or more — the site on Wednesday showed data from June 14-20 — and it also may not be precise enough to distinguish places seeing a second wave from those that are merely testing more aggressively.
Still, researchers say the new website offers a helpful addition to the conversation.
“It is good to show the county level because (looking just at) the whole state doesn’t really tell the whole story,” said Jaline Gerardin, a Northwestern University assistant professor of preventive medicine who works on virus modeling.
“Could there be better indicators? Yes. Are we working toward that? Yes,” she said.
For now, here’s what’s available to the public.
Case numbers and test results
The website offers a new way to look at some of the same data the state has been monitoring for months, plus some additional data never before shared.
One set of metrics involves the most-cited figures used to track the pandemic: the number of new cases, and — of new people tested for the virus — the percent who test positive.
The state’s new website measures these figures weekly, which is new. Another new feature is that the site takes the county’s population into account, making it easier to compare bigger and smaller counties. The state’s threshold for concern is the number of new weekly cases climbing past 50 per 100,000 residents or the positivity rate reaching 10% or more.
That latter calculation is the one most useful to help detect a second wave, said Nigel Goldenfeld, a University of Illinois physics professor who is working with university colleague Sergei Maslov to develop COVID-19 case forecasts.
“If this ratio is small, then it means that the disease is well under control. By testing you are unlikely to find anyone new with an infection,” he said in an email. “If this ratio is large, then you have a good chance to find someone new with an infection, so that means the infection is prevalent.”
He cautioned, however, that the 10% threshold may be too high to signal a problem, because most places that have controlled the epidemic have dropped that ratio below 3%.
As it is, the heart of the early pandemic in Illinois — Chicago — scores below both thresholds, at 42 cases per 100,000 people, with a 5.6% positivity rate. (The site splits Chicago from suburban Cook County.)
Among the suburban counties, only Kane County scores higher than the threshold at 58 cases per 100,000. Other rates range from 21 in McHenry County to 48 in suburban Cook.
(Jemal R. Brinson)
(Jemal R. Brinson)
Hospital visits and admissions
Another set of metrics focuses just on cases serious enough to send people to the hospital.
One measure looks at hospital capacity: whether plenty of ICU beds are available. It’s the only metric measured by region of the state, not by county. At least 20% of ICU beds should be open. So far, across Illinois, that hasn’t been a problem. At worst, the region covering the southwest suburbs had 38% available ICU beds during the week analyzed. (By Tuesday, other state data showed that figure climbing to 43%.)
Two other metrics look at hospital data a different way, based on numbers of patients.
One focuses on emergency room visits. It looks at the ratio of people coming to the ER who complain of COVID-19-like symptoms. Another looks at weekly hospital admissions, also with those symptoms.
The website offers no cutoff between good and bad. Rather, it’s about making sure the figures, whatever they are, are stable or declining.
For example, when Chicago residents went to the ER in the most recent week measured, just 3.4% complained of COVID-19-like symptoms. Seven weeks earlier, it was near 14%. So Chicago improved significantly on that measure. The raw number of ER visits with those symptoms also dropped in that same period from 2,008 to 314, according to the website’s underlying data.
The same is true of weekly hospital admissions, which for Chicago residents was 182 in the most recent week of data reported, down from a height of 1,119 seven weeks earlier.
(Jemal R. Brinson)
The figures come with a big caveat: Not all people with these symptoms will actually have COVID-19.
It also can be tricky to judge ups and downs when looking at individual counties, particularly less-populated ones that have seen fewer COVID-19 cases. So the state will give counties a warning label if either metric increases by 20% over two consecutive weeks.
Who got warnings?
In all, eight counties got a warning label in at least one category, usually for having a higher rate of new cases per 100,000 residents.
But the only county colored orange on the new map is Cass County, in central Illinois. It got warnings for a high rate of new cases, for a high positivity rate from that week’s tests and for insufficient testing (a warning triggered automatically when a county’s positivity rate is too high).
What happened? According to the county health department, a worker at a small nursing home went to the local hospital with COVID-19-like symptoms during the week of June 14. That triggered a massive set of tests the next day of all workers and staff at the facility, which found 10 employees and 11 residents to be positive for the virus.
“I think we caught this fairly early, although you cannot tell by the spread,” said the county’s health administrator, Teresa Armstrong. “At the very beginning, when we were doing interviews, most people (testing positive) were saying they were asymptomatic, except for some congestion and things they were attributing to seasonal allergies.”
Among health officials, what happened at the nursing home is called a cluster. And the state put a special category on the website to report, for each county, the percentage of new weekly cases tied to clusters. Yet, for Cass County, that figure is listed as only 4.2% for the week of June 14-20.
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Armstrong said that figure is wrong and should be 84%. She said the state pulled the data for the metric from a shared government health database on June 19, before her staff could update the database to show cases were linked.
Subsequent testing at the nursing home has found another nine employees and 19 residents who were positive, suggesting the county will likely miss targets in the next weekly update as well.
The situation in Cass County highlights another caveat for Illinois residents: Be careful rushing to judgment based on these figures.
As Northwestern’s Gerardin said: “The fact they went into a long-term care facility and found a bunch of cases is a good thing — and now they’re the only orange county in all of Illinois.”