Iowa Has Been Putting The Wrong Date On Some Coronavirus Cases, Skewing State Data
An Iowa public health official says the state is trying to fix a data problem that results in some new coronavirus cases being recorded as occurring weeks or months earlier.
That can make the number of new infections and the percent of positive tests look lower as school leaders are using that information to make decisions about bringing students back to the classroom.
Nurse practitioner Dana Jones of Iowa City has been tracking the state’s coronavirus data since mid-May and documented the discrepancies. She reached out to the Iowa Department of Public Health, and an epidemiologist confirmed the problem in an email to Jones.
“I think the fact that the data is wrong, and that’s what we’ve been driving our decisions on, is concerning,” Jones said.
Jones' findings were first reported by Bleeding Heartland.
Jones estimates thousands of reported infections could be wrongly backdated, but said only the IDPH knows the true number of new coronavirus cases that were detected each day across the state.
“We recognize this is a problem and have been working on logic to handle it,” IDPH Surveillance Unit Lead Epidemiologist Rob Ramaekers said in an August 14 email to Jones.
Ramaekers wrote that the IDPH system generates a date for when a test is first reported.
“So if I tested negative in March and was reported to IDPH, I would have a ‘Reported to IDPH’ date of March,” Ramaekers wrote. “If I was tested again today and came back positive, my ‘Reported to IDPH’ date does not change and now suddenly I appear on the graph in March.”
IDPH spokesperson Amy McCoy did not answer IPR’s questions about this Monday afternoon, saying she was “still working on getting information.”
Gov. Kim Reynolds told school districts they must return to mostly in-person learning unless the county the school is in reaches 15 percent average test positivity over 14 days, a measurement that was already called into question by infectious disease experts and is also skewed by the IDPH’s flawed data.
The Iowa Falls Times Citizen reported the state’s backdating of new cases in Hardin County led to a significant difference from numbers reported by the county health department. Using the state’s data, the Times Citizen calculated a 7-day county test positivity average of 8 percent. Using local public health data, the 7-day average was 14.5 percent.
Jones called on the IDPH to fix its coronavirus data website.
“I would like for them to make some sort of statement to the public saying why this happened, what they’ve done to fix it, how it changed the data that we’ve used, and what the implications are,” Jones said. “And I’d like for them to speak to that because I think they owe that to the public.”
The Iowa Department of Public Health also appears to have changed how it calculates the 14-day average test positivity rates for counties. That’s what the state says school districts should look at to inform their school reopening plans.
Last week, the Dubuque Telegraph Herald reported the state was adding up each day’s positivity rate and dividing by 14.
Now, the state’s coronavirus website says, “The formula for calculating the % positivity 14-day average is the sum total of individual Positive Cases (14 day) divided by the sum total of Total Individuals Tested (14 day).”