Illinois coronavirus: State officials move away from measuring test positivity rate

One of Illinois’ best-known COVID-19 barometers goes away.

The state Department of Public Health announced on Tuesday that it would no longer release seven-day average case positivity rates — numbers that since the early days of the pandemic had offered a quick glimpse into the rampant spread. of the virus at some point in different regions or across Illinois as a whole.

The change in coronavirus data reporting follows new guidelines set by the US Centers for Disease Control and Prevention, which place greater emphasis on hospitalizations and case rates per 100,000 population.

With vaccinations and home testing being more accessible, experts say these numbers give a better idea of ​​the trajectory of the virus.

Positivity rates, which compare the number of confirmed positive tests to the total number of tests performed, are “outdated” at this point in the pandemic, according to Illinois Acting Director of Public Health Dr. Amaal Tokars.

Illinois Acting Director of Public Health Dr. Amaal Tokars speaks during a virtual briefing on Tuesday.

Illinois Department of Public Health

“Test and case positivity rates were seen as a good way to monitor the level of community spread early in the pandemic. At this point, now that we have effective vaccines and therapies, it is more useful to rely on data that indicates the rate of cases, the severity of the disease and the level of pressure on [the] health care system to guide our public health recommendations,” Tokars said.

Updated CDC guidelines mean states don’t have to tally all negative antigen tests for public health officials, so the state can’t calculate positivity rates anyway.

Instead, the Ministry of Public Health highlights county-by-county CDC metrics which were rolled out earlier this year with indoor masking guidelines: the number of new COVID cases detected per 100,000 population in the past seven days; the number of new COVID hospital admissions per 100,000 population over the past week; and the percentage of inpatient hospital beds occupied by COVID patients.

Those numbers are considered low in 98 of Illinois’ 102 counties — including the entire Chicago area — meaning most people don’t need to wear masks in indoor public places.

But four counties in southern Illinois – Pope, Gallatin, Saline and Hardin – have reached the “high transmission” level, as cases have been slowly increasing across the state for about three weeks.

“This is happening in an overall much lower case context than what we have seen in winter, but [we’re] still seeing a steady increase now,” Tokars said.

New cases of COVID-19 per day

Graphic of Jesse Howe and Caroline Hurley | Sun-Times

Source: Illinois Department of Public Health

The graph is not displayed correctly? Click here.

The statewide average case rate has gone from a rate last week of about 10 infected residents per 100,000, to a rate of about 14 per 100,000. That figure has topped 250 at most. strong from the surge of the Omicron variant.

Chicago averages about 16 new cases of COVID-19 per 100,000 residents per day.

At the same time, the statewide daily hospital admission rate fell from about 30 COVID-19 patients a day to 34. It had previously peaked at 861 in early January.

University of Chicago epidemiologist Dr Emily Landon said the shift to focus on hospital admissions and case rates made sense as the number of tests was inflated by the tests required by hospitals for patients undergoing procedures, as opposed to people with potential COVID symptoms seeking a diagnosis.

“The testing figure has been diluted. It was a really good indicator at first, but you have to adjust your metrics based on people’s behavior,” Landon said. She stressed that residents shouldn’t abandon precautions just because the CDC has labeled their area a “low transmission” area.

Dr. Emily Landon, executive medical director of infection prevention and control at the University of Chicago, speaks to reporters in the Blue Room in February.

Dr. Emily Landon, executive medical director of infection prevention and control at the University of Chicago, speaks to reporters in the Blue Room in February.

File Tyler LaRivière/Sun-Times

“Their job is to protect the common good, not the individual good. If you have an immunocompromised condition or live with someone who does, mask up, avoid crowds,” she said.

Dr. Michael Angarone, associate professor of medicine in Northwestern Medicine’s Division of Infectious Diseases, said the change reflects a step toward “the kind of phase of living with the virus.”

“In a way, it’s endemic. It’s here, and we’ll get those periodic surges, but that doesn’t mean it’s any less serious. It is essential to get as many people vaccinated as possible,” Angarone said.

About 73% of Illinois residents are considered fully vaccinated.

For help finding a photo, visit chi.gov/covidvax or call the city’s COVID-19 hotline at 312-746-4835.

Lillian L. Pena