EVANSVILLE — Standing outside Mesker Park Zoo's Penguins of Patagonia exhibit on the morning of Oct. 28, Evansville Mayor Lloyd Winnecke offered a tip.
The city would announce within the hour that it was lifting mask mandates for its properties in light of encouraging new COVID-19 data released the day before. The announcement came quickly, and it was broader: Masks requirements were lifted for all city and Vanderburgh County buildings and all Evansville Vanderburgh Building Authority-owned buildings — including Ford Center, the Civic Center complex, the jail and the sheriff's operations center, among others.
But a key component of the encouraging new data policymakers relied on wasn't new at all. It was drawn from testing positivity rate data that was nine to 15 days old. The mask mandates are still rescinded, but since then case and positivity rate data have grown worse.
Coming back:Mask mandate returns to University of Evansville, continues for USI and Ivy Tech
The Building Authority, which issued the Oct. 28 announcement, cited Vanderburgh County's move to a lower level on Indiana's COVID-19 severity map. Late the day before, the Indiana State Department of Health had reclassified Vanderburgh County on its map from "orange," the second-highest level of severity, to "yellow," the third-highest.
Local policymakers hailed the good news. Mask mandates imposed at the height of August's delta variant-fueled surge were gone within 24 hours.
On Wednesday, the state's COVID-19 severity map — the same measure that draws from positivity rate data nine to 15 days old — put Vanderburgh, Warrick, Posey and Gibson counties back in its "orange" category.
A calculation that relies on old data
ISDH assigns its color shades to counties using a 7-day moving average of the positivity rate for all COVID-19 tests plus less dated numbers onweekly cases per 100,000residents. It releases a new color-coded severity map each Wednesday.
"To calculate test positivity rate, (the health department) will utilize Monday’s 7-day average for the all tests positivity rate for each county," states an ISDH explainer for its color-coded maps. "Please note that this calculation is lagged by six days to ensure complete testing information has been received."
The Monday average uses data collected from the previous Monday through Sunday.
More:With COVID-19 on rise once more, Indiana reports 3,481 new cases across the state
It means the seven-day moving average is staked back by a combined nine days — at its most recent — when the state's "new" color-coded map is issued. And being a moving average of seven days' worth of data, it draws upon COVID-19 tests administered more than two weeks before the map is published.
The data is even older if one consults the state's map on a Tuesday night or a Wednesday morning, just before a new map is issued. That means looking at a moving average involving tests administered as much as three weeks earlier.
To illustrate this, hovering over Vanderburgh County on the state's map on Wednesday morning — a map issued on Nov. 10 — showed a "7-day all tests positivity rate" of 7.28%. But the county's positivity rate seven-day average last reached that number nine days earlier, on Nov. 1 — and, as a seven-day moving average, it included test data collected as far back as Oct. 26.
That's 15 days before Nov. 10. The positivity rate data for a color-coded map issued Nov. 10 and still up on display Wednesday morning barely accounted for any test results collected in November.
The map issued later in the day Wednesday said Vanderburgh County's seven-day all tests positivity rate was 9.21%. That was the figure on Nov. 8. It included test data collected as far back as Nov. 2 — 15 days before Wednesday's new map appeared.
When the Building Authority and city and county policymakers used the map issued on Oct. 27 to lift mask mandates in a sweeping array of local buildings, they were relying on testing data that had been collected no later than Oct. 18.
It's a trade-off: More recent COVID-19 data or more accurate COVID-19 data?
Local COVID-19 data hasn't looked any better since the day the decision was made. Vanderburgh County's seven-day moving average of COVID-19 cases on Oct. 28 was 32. It was 50 on Nov. 13, the most recent date available. The seven-day average positivity rate was 7.6% on Oct. 28. It was 9.7% on Nov. 13.
Dave Rector, general manager of the Building Authority, was surprised when the Courier & Press showed him the state's methodology and its implications for policymakers who rely on the color-coded COVID-19 severity map to make decisions.
"You’ve brought something to light for me. I thought we were looking at the past week’s data," Rector said.
More:COVID-19 mask mandates for Evansville, Vanderburgh buildings lifted after county goes to 'yellow'
It's not hard to see why someone would think so. The color-coded map states, "Below results are as of (the date of the Monday or Tuesday one or two days before)," but the disclaimer does not mention any reporting lags. It does say cases, deaths and tests "have occurred over a range of dates" but were reported in the last 24 hours.
More recent daily COVID-19 data is readily accessible in spreadsheets within ISDH's Indiana Data Hub, but that information changes often as more tests are processed.
ISDH is plain about where it stands in the tradeoff between more recent COVID-19 data and more accurate COVID-19 data.
In the Vanderburgh County Daily Positive Test Rate graph on ISDH's statewide dashboard, a disclaimer states: "Receiving enough testing data to perform rate calculations typically takes six days. Therefore, the data within the preliminary shaded area are provisional and should not be characterized as comprehensive and complete data."
Rector is also plain about where he stands, now that he understands the state's methodology.
"I’d rather have more real-time data," he said.
Rector stressed that the decision to lift the Building Authority's mask mandate was done in consultation with city and county elected officials and judges who occupy the Civic Center's courts complex. The others rely heavily on the guidance of Joe Gries, administrator of the Vanderburgh County Health Department.
"And then foremost, Joe Gries. 'Joe, what are you thinking, what are you seeing? Where do you think we ought to go?'" Rector said.
Some two weeks before the mask mandate was lifted, Gries told the Vanderburgh County Commissioners he would be comfortable ending the requirement only when the county dropped to "yellow" or "blue," a lower level of severity, on the state's map.
On Tuesday, Gries said he can't control the data the state puts out.
"They’re the purveyors of the information, and that’s what we have," he said. "We don’t have any ability to get test information any quicker than what they put out."
'What if we’re spiking and we don’t know it yet?'
On Monday, two days before Vanderburgh County was classified "orange" again, the Courier & Press showed Rector the more recent but likely incomplete data available in the Indiana Data Hub.
"What if we’re spiking and we don’t know it yet?" he said. "Now, we would know that maybe from the hospitals, perhaps. Perhaps."
The most recent color-coded map that was issued later Wednesday included testing data up to Nov. 8. The map that will be released next Wednesday — Nov. 24 — will include data no more recent than Nov. 15.
Gries said earlier this week that reinstating the mask mandate based on the state map's more complete (but older) data likely would be a matter of how bad the numbers looked.
One important fact gets lost in discussions of mask mandates, the health department administrator said.
"You don’t have to have a mask order for people to wear masks," he said. "We recommend anybody that’s unvaccinated, they wear their masks when they’re out in public. We recommend people getting vaccinated.
"There are ways to protect yourself and your family and people around you."