SALT LAKE CITY — It's refreshing to see Utah's COVID-19 epidemiological curve drop in the recent weeks after months of case increases; however, there are signs that recent case counts don't show a complete picture of COVID-19 in the state.
In a conventional sense, the spread of COVID-19 can be determined by simply looking at new cases discovered through testing. But what happens when testing for the coronavirus isn't exactly consistent?
That's where other statistics help piece together how COVID-19 is currently impacting the state.
Confirmed cases down, positivity rate slowly rising
The Utah Department of Health reported 972 new cases of COVID-19 from tests taken on Friday and 802 on Saturday. Those figures were the lowest single-day increases reported since early October. In fact, it snapped a stretch of 1,000 or more new daily cases announced by the health department that dated back to Oct. 12. The department reported another 1,700 cases from tests Sunday, which is also well below the seven-day rolling average ahead of Christmas.
The state's COVID-19 epidemiological curve and seven-day rolling average of new cases have also been in decline since around Dec. 10.
That said, testing is another figure that's fallen off in that same time. For example, more than 15,000 people were tested for COVID-19 on Dec. 9 — the most tests conducted after Thanksgiving, according to health department data. Aside from a few outliers, the state has mostly reported days with fewer than 10,000 tests conducted since then. Testing was not conducted on Christmas Day and testing sites closed early on Christmas Eve, but the downward trend is visible on a graph before the holiday.
Meanwhile, the percentage of positive tests to tests conducted, commonly referred to as positivity rate, has only increased since about the time that cases declined. As of Monday, Utah's seven-day rolling average positivity rate is 24.4% through that backdate of Dec. 22. Preliminary data from over the weekend indicated positivity rates closer to 30%, which means the number will rise in the coming days.
Experts have said that positivity rate is an important statistic because it can provide a better assessment of how prevalent a virus is in a community when testing numbers widely fluctuate and become unreliable. In this case, the positivity rate is the largest sign that COVID-19 isn't quite leaving Utah, even if case counts are falling.
"We're certainly concerned because it represents high level of community transmission," said Dr. Todd Vento, an infectious disease physician for Intermountain Healthcare. "Hence, it's why we're constantly monitoring the situation to see if there's any additional measures that we need to take to address that."
Vento said health officials don't know exactly why testing is currently down; however, they have seen trends throughout the pandemic and from illnesses different from COVID-19. On a smaller scale, some days — like Sunday and Monday — yield fewer testing than other days. Those are believed to be tied to when someone is expected to be out in public for any reason, such as work.
"The same sort of concept after holidays," Vento said. "We've seen in the past where the numbers were down right away. The numbers yesterday were very low, which folks kind of — for a lack of better word — are waking from their slumber from the holidays and maybe on, say, Tuesday or Wednesday they'll start thinking 'OK, I'm going to go get tested.' That's not unusual for other respiratory illness as well."
Since testing was down, he said the epidemiological curve and seven-day running average of case counts will be "maybe not as accurately reflecting what's out there in the community" especially when it takes into account days where testing was limited.
That's where the positivity rate comes into play.
"You can't look at just the cases and the case seven-day rolling average because it won't accurately reflect a same number of tests that were done," he added.
As for Utah's positivity rate, it's been a roller coaster over the past few weeks. After climbing to 25.4% on Nov. 10, it fell 21.8% on Nov. 22 — a few days before Thanksgiving. It rose again to a current all-time high of 27.2% on Dec. 1 before it fell back down to 22.3% on Dec. 13. It's steadily climbed since then but at a much slower rate.
What's happened with COVID-19 hospitalizations?
Of course, the biggest concern with COVID-19 is any impact it has on hospitals and deaths. Vento said that Utah hospitalizations due to the coronavirus have stabilized and even fallen a little bit. That's a welcome sign for a statewide hospital system that was on the brink of full capacity.
Hospitalizations due to COVID-19 typically lag behind new cases, so the state's current peak of 606 hospitalizations on Dec. 4 was primarily the result of climbing COVID-19 cases prior to Thanksgiving. Public health experts warned about holiday gatherings with the fear that hospitalizations would only grow.
It appears Utahns heeded the pandemic recommendations for at least Thanksgiving. While many new cases were still reported, it wasn't nearly as many as feared. As a result, the state health department reported just before Christmas fewer than 500 hospitalizations due to COVID-19 for the first time since mid-November.
"While the nation had a surge within a surge — (there was) a fall surge and then a post-Thanksgiving surge for the United States — we didn't see quite that level of increasing cases after Thanksgiving as we were figuring or concerned about, which is very good," he said.
He added that hospitals have also learned to shorten stays for patients who don't require ICU care by providing at-home recovery models so people are able to leave the hospital sooner.
Data might show that COVID-19 hasn't left the state even as new cases decline, but one positive sign is that new hospitalizations due to the coronavirus are on the decline.
The state health department recently began to report the seven-day rolling average of new hospitalizations per day on top of current hospitalization figures. Utah reached a seven-day average of 92.4 hospitalizations per day on Nov. 18. That was the day a record 116 new Utahns were admitted to a hospital due to COVID-19.
The average fell to 71.2 new hospitalizations per day as of Dec. 22, which is the first day beyond the department's period of incomplete new hospitalization data. These figures are still high, especially compared to numbers before November. Nevertheless, it shows that following guidelines for Thanksgiving gatherings helped not just lower the growth of new cases but also helped lessen the impact on hospitals.
The jury is still out on whether December holiday gatherings will have factored in any way as the holiday season doesn't really conclude until after New Year's Day, Friday.
Outlook heading into New Year's
All the health recommendations for Thanksgiving, Hanukkah, Christmas and Kwanzaa apply to New Year's. That means health officials advise that people celebrate the holiday at home and connect with other households virtually.
Intermountain Healthcare even promoted a do-it-yourself New Year's Eve ball drop out of a styrofoam ball and a wood dowel as one way to celebrate the holiday at home in a fun and safe way.
Vento's colleague, Dr. Eddie Stenehjem, another infectious disease physician for Intermountain Healthcare, said last week he anticipated COVID-19 testing will increase after New Year's Day. One of the main reasons for that, he said, is that Utah colleges will begin their mass weekly testing of students who remain on campus for the spring semester.
Once that begins, the positivity rate will be another key factor as testing numbers may exceed previous testing norms.