EVANSVILLE — If you go by the data points that signal COVID-19's danger, it's waning right now. But buckle in, because trouble probably is coming, local medical leaders say.

Ascension St. Vincent Evansville is girding for another surge in coronavirus cases to go with flu season this fall and winter, said Dr. Heidi Dunniway, the hospital system's chief regional medical officer. It's logical. People will be indoors more often, in close contact and sometimes not masking, Dunniway said.

How big the COVID-19 increase will be is a question that has St. Vincent on edge.

"I think we’re all preparing for it," Dunniway said. "I wish we knew for sure what we were going to be facing, but we certainly are trying to ready ourselves in the event that it does have an uptick."

More:Evansville family says Walgreens made frightening vaccine blunder with their children

Deaconess Health System also expects increases.

"Infectious disease experts across the nation aren’t yet sure what to predict this fall and winter, but based on prior experience, including last year’s holiday season, there is likely to be some increase," said a statement by Deaconess President Dr. James Porter.

"COVID-19 will still be circulating among the population to some degree, and if unvaccinated people gather, there will be new infections."

On the face of it, the data says the delta variant-fueled surge that stormed Southwest Indiana and Henderson County, Kentucky in August and September is over.

Vanderburgh County recorded more than 1,300 COVID-19 cases in the final week of August — and a number 71% lower last week. Deaconess Health System reported on Sept. 1 it had 179 COVID-positive hospitalized patients. The number was 97 on Monday.

And Wednesday brought the news that Vanderburgh, Warrick, Posey and Gibson counties are at an orange level of COVID-19 severity, according to the state's newest map. Orange indicates medium to high community spread. Red is the highest level of severity.

But there are warning signs deeper inside the numbers, Dunniway said. She pointed to "a sawtoothed pattern" of waxing and waning case totals.

A Courier & Press analysis shows that since Sept. 30, Vanderburgh County has recorded daily new case totals ranging from 95 to 44 on weekdays. The numbers mark the dates positive test specimens were collected, not reported. The weekday positivity rate ranged from 12.4% to 7.6%.

"We certainly are still seeing new cases, and we also know that we don’t have the degree of vaccination that we’d like to see to really get herd immunity," Dunniway said. "So I definitely would recommend we all exercise caution in getting too comfortable with the pattern that we’re seeing."

Joe Gries, administrator of the Vanderburgh County Health Department, told the county board of commissioners Tuesday that he won't be comfortable dropping the mask mandate for county-owned buildings until Vanderburgh County reaches lower levels of COVID-19 severity on the state's map.

More:Hospitals offer exemption for COVID-19 vaccine mandate. Many employees took it.

One recent scary number can be dismissed as a mirage.

Vanderburgh County reported 189 new coronavirus cases on the Indiana State Department of Health's statewide dashboard Wednesday. But the dashboard shows new cases entered into the state's system each day regardless of when test specimens were collected. No more than 85 positive test specimens have been collected in Vanderburgh County on any day this month.

'The real question is....'

Similar seasonal conditions as last fall and winter have Dr. Micah Pollak, one of Indiana's leading COVID-19 data researchers, anticipating another, albeit smaller, wave of new cases this year. But with several caveats.

Pollak, an economics professor at Indiana University Northwest, outlined his theory during a Wednesday taping of "Newsmakers," a Tri-State television show offered by the Courier & Press, The Gleaner and WNIN-PBS9.

Pollak pointed out that last winter's large outbreak of coronavirus cases was preceded by a smaller wave of new cases in the summer and fall. This year brought another large wave in August. That wave was fueled by the more contagious, more easily spread delta variant but tempered by the fact that Vanderburgh County had fully vaccinated tens of thousands of residents.

More:Vanderburgh County's COVID cases fall 8.6%; Indiana cases fall 8.9%

"You could draw a parallel between the wave we’re just getting out of now and the small wave we had last summer," Pollak said. "The problem is going forward, last year around this time we entered into the really big winter wave that was the worst of the entire pandemic.

"So the real question is, this last wave we just got out of – was that kind of instead of the big winter wave, or was that just the wave before the big winter wave?"

One local group stands most vulnerable in any new wave

Any new fall and winter wave of COVID-19 cases would draw a bead on Vanderburgh County's most vulnerable population, Pollak told the Courier & Press: unvaccinated residents 65 or older.

Centers for Disease Control and Prevention (CDC) data, considered more comprehensive and inclusive than the state's dashboard, shows 88% of Vanderburgh County residents over 65 have been fully vaccinated.

How many people does that leave?

U.S. Census Sex by Age data shows more than 31,000 local residents are over 65 — but those figures are an imprecise projection. The census bureau's own margin of error is more than 5,000. Also, the most recent numbers were collected in 2019 — before several hundred local residents over 65 died of COVID-19.

More:Everything you need to know about getting a flu shot amid the COVID pandemic

Pollak pointed out that some local residents over 65 may have been vaccinated out-of-state without Indiana knowing it.

The data analyst's best guess for the number of unvaccinated senior citizens in Vanderburgh County is between 2,000 and 7,000.

The good news, Pollak said, is that any new wave of cases will bring infections but likely won't result in anywhere near the volume of deaths seen last year. The over-65 group's large vaccination rate is the reason.

"When we see case numbers rising now, there’s going to be a disconnect between cases and deaths in a way that didn’t happen before," he told Newsmakers. "Previously, last year around this time, a certain percentage of cases resulted in deaths. This year that percentage is going to be much lower."

According to Vanderburgh County Health Department data, 285 county residents died of COVID-19 in 2020.

More:Vanderburgh County COVID-19 vaccine tracker: 51% of people fully vaccinated

Dunniway said the over-65 group must be identified and vaccinated ahead of any new wave of cases.

"It becomes increasingly important for everyone who’s not vaccinated to do so or seriously consider doing so, and to take action – but particularly individuals over 65 or those who are at higher risk for severe disease because of underlying health conditions," she said.

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