Woodbury County’s public health department on Wednesday stopped sharing new daily COVID-19 data that it has shared since the first coronavirus case surfaced in the county.
Iowa City nurse practitioner Dana Jones discovered a data error that has potentially reported thousands of recent coronavirus cases as happening months earlier. Jones said she is concerned that positivity rates may look lower than they are.
Siouxland District Health Department Deputy Director Tyler Brock said the county health department disagrees with that and believes the glitch has skewed Woodbury and other counties' positivity rates higher, because it also affects negative test results. He said positive tests are “eventually getting reported," but a person’s second, third or fourth negative test isn’t getting put into the system.
“Well that’s an important piece of the math, right?” Brock said. “When you’re talking about the positives versus total tests, that’s how you get your rate.”
The county health department doesn’t want to report new daily positive cases without accurate negative case data that paints a full picture of the situation. It's possible they could bring back the new daily case reports, Brock said, but five months into the pandemic, “The daily updates are less important than the trends over some time.” Brock asserted that weekly reports have more data and give a more accurate snapshot of COVID-19 in the county.
Since Woodbury County’s first confirmed case surfaced in late March, Siouxland District Health has been breaking down countywide COVID-19 data on its website by the number of new confirmed cases, total confirmed cases, deaths and recoveries. The health department has also shared these daily updates in emails with media.
“For some time now, SDHD has been concerned about how the daily positives we report don’t always line up with the daily difference in total cases on the IDPH website,” Siouxland District Health said in a statement Tuesday. “The reason is due to the existing database used for managing communicable disease cases in Iowa and how it handles people that have been tested for COVID-19 more than once. This system is intended to track individuals, or ‘cases’, not total tests.”
Brock said Siouxland District Health's concerns with the case counts date back to around the time the state's coronavirus website went live in late March, but the county health department continued to report daily updates because “it was at least consistent.”
Iowa’s coronavirus website pulls data from the state’s communicable disease database that manages numerous infectious diseases, like salmonella, Brock said. But a person who has salmonella isn’t going to get re-tested a month or two later, like someone who might get tested multiple times for COVID-19.
“We’re dealing with a system that was intended to handle a few hundred salmonella cases a year along with some of the other infectious diseases that we deal with all the time,” Brock said. “It was not necessarily to deal with something of the magnitude of COVID.”
Woodbury County has more than 3,800 total coronavirus cases. In late April and early May, the county was seeing dozens to more than a hundred new cases a day. Since then, the 14-day average positivity rate has decreased and has been hanging around 6-8 percent. As of Wednesday, the county is at a 7.4 percent positivity rate out of total tests done, according to the state coronavirus website. Brock estimated the county’s positivity rate could be at least a percentage point lower than as listed.
“We do still have significant spread in Woodbury County and I wish it was lower,” Brock said. “We still have more spread than what we like to see. But we've been very, very consistent over the two plus months in our percentages.”
The governor’s office says the state recording error is being fixed.
