Wisconsin Covid-19 Testing – Serious Validity Concerns Over Backlog of Negative Results

     Senator Steve Nass (R-Whitewater) is calling on state and local public health officials to publicly announce if their agencies currently have backlogs or had backlogs at any time since at least June 1, 2020, in reporting negative Covid-19 test results.  He is also demanding that state and local public health officials appropriately correct all data, particularly positivity rate calculations, upon entering all backlogged negative results. 


     “After the stunning revelation that Dane County had 17,000 unreported Covid-19 negative results that dramatically skewed the positivity rates in that county for at least three weeks, the public can no longer be assured that all state and local data is reliable without greater transparency and honesty from public health bureaucrats.  In every corner of Wisconsin, local governments, private businesses and individual citizens have been using the flawed Covid-19 data to make key decisions and now must reevaluate those decisions once the accurate positivity rates are known,” Nass said.


     The Wisconsin Department of Health Services (DHS) has acknowledged that Dane County is not the only reporting agency in the state with a backlog.  However, DHS has refused to identify the local public health agencies with backlogs in entering Covid-19 negative test results.


In Dane County’s situation, according to an analysis by WKOW – Channel 27 in Madison, the inclusion of the 17,000 negative results had the following impacts on positivity rates, as of July 18th:


-The 7-day positivity rate dropped from 13.4% to about 4%.

-The average daily positivity rate dropped from 6.1% to 2.1%.


“There is no doubt in my mind that the state positivity rate and many local county positivity rates are skewed significantly higher by the backlogs in reporting negative results.  While the development of backlogs was not intentional, the decision by public health officials to stay quiet about the existence of the backlogs was clearly intentional and terribly inappropriate,” Nass said.


DHS has provided limited information regarding the backlog even with their confirmation it exists and is significant.  Here is what we know:


-Most counties are attempting to enter positive Covid-19 test results in the state data collection system within 1-3 days.


-Counties that have seen increases in Covid-19 testing volumes over the last two months (which is most of the 72 counties) have dealt with backlogs in entering the negative results into the state system.  Often the delay is believed to be about 5-6 days, but there are situations like Dane County that have run 10 days or more in backlogs.


Nass noted that when DHS provides its daily Covid-19 briefing, the public and media are given the impression that testing data is timely and accurate.   He emphasized that the backlog in entering negative results dramatically skews the percentage positive calculations (this includes the daily percentage, the 7-day percentage and the 14-day rolling average) used  in determining if we are identifying more cases due to increased testing or are in a period of increasing spread of infections for other reasons.

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