McHenry County Board chairman disagrees with decision to use state's higher positivity rate

Updated 10/22/2020 4:16 PM

A key metric used by the Illinois Department of Public Health to decide whether a region should face additional restrictions is being adopted by the McHenry County Department of Health, the local agency announced Wednesday.

The McHenry County health department said it would align its methodology for pursuing the county's positivity rate with the one used by the IDPH, resolving a discrepancy between numbers produced by the two public health agencies.


This discrepancy has been reported on and noticed before. Last Thursday, the IDPH reported an average positivity rate of 8.4% for the past seven days, but the county health department reported 6.2% for the same metric.

Based on the state's numbers, McHenry County now is at warning level for potential COVID-19 restrictions if these numbers do not improve.

McHenry County Board Chairman Jack Franks said he disagreed with the local health department's decision to align with the state department's positivity rate metrics because he said he thinks the county's numbers are more accurate than the state's.

He said he fears using the state's higher positivity rate, instead of the county health department's, means there's a greater likelihood the county will go into mitigation.

"I urge (the McHenry County Department of Health) to change their position," he said. "Because we need to continue to educate our citizens and have people ... wear their masks and do the social distancing and wash their hands. But we also have an obligation not to agree to numbers that we don't believe are correct."

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A McHenry County health department spokeswoman could not be reached for comment on if aligning the county positivity rate with the state's could mean using more mitigation strategies to stop the spread of COVID-19.

Test positivity is one of eight metrics used by the state to evaluate warning signs of increased COVID-19 spread in a community. McHenry County is seeing cases rise dramatically and recently saw the highest single day lab confirmed case increase since the COVID-19 pandemic began.

The positivity rate produced by the county also is one of four metrics the health department recommends school districts use in deciding whether to switch between learning models with more or less in-person instruction.

According to the McHenry County health department, preliminary research into these discrepancies can be attributed to several differences in the local and state health department's methodology for calculating positivity.


The McHenry County health department calculates positivity using a method previously used by the IDPH, according to a news release.

The county health department makes every effort to count each person tested only once, so multiple test results for a single individual do not inflate positivity, but the state counts every positive and negative test even if they come from the same person.

The county health department said this is considered to have a minor impact on positivity.

"After careful consideration, the McHenry County health department has decided to present the positivity statistics provided by the State," the health department said in a news release. "Although the McHenry County health department has complete confidence in the methodology it has been using, the health department has decided to utilize the same data as IDPH to stay consistent with how the state is interpreting and measuring positivity."

During a county board committee of the whole meeting last week, Public Health Administrator Melissa Adamson told officials that for a long time, the numbers were similar. However, during the previous week, officials noticed a difference between what the state and county were reporting for McHenry County's positivity rate, she said.

The county health department is mandated to perform case investigations and contact tracing to isolate and quarantine individuals to slow the spread of disease. The health department is seeing a high level of noncompliance with its investigations, hampering efforts to slow the spread of COVID-19 in the county, according to the news release.

"It's extremely important for everyone to participate in case investigations and contact tracing so the proper public health authority can advise its residents on ways to mitigate the spread of the virus in their homes and to those closest to them," Adamson said in a statement.

She asked residents to answer the phone if they receive a call from (312) 777-1999 or COVID Contact and help the health department "slow the spread of COVID-19 in McHenry County."

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