LEWISTON — Newly released data from the Maine Center for Disease Control and Prevention’s wastewater testing program shows the prevalence of COVID-19 found in the Lewiston-Auburn area has decreased in recent weeks.

In recent months the Maine CDC has shifted away from daily case counts and toward other metrics, such as hospitalizations and wastewater testing, as a means to measure where Maine stands with respect to the pandemic.

The changes come after the fast-spreading omicron variant has overwhelmed the state’s disease surveillance systems and the strain’s “scientific reality” renders some tools of the pandemic’s past, such as contact tracing and daily case counts, virtually obsolete.

As of Wednesday, for example, Maine CDC Director Dr. Nirav Shah said the agency had a backlog of 53,000 positive tests awaiting review. With omicron the dominant variant in the state, the Maine CDC has regularly dealt with a daily backlog of tests that is tens of thousands deep.

Epidemiologists are able to circumvent those challenges with the use of wastewater testing. It works by taking a sample from a municipal wastewater source and testing for the concentration of the virus in the water.

“It gives us a picture of how much COVID is in a community at any particular point,” Shah said at a media briefing last month.

“We’ve learned from the wastewater testing that’s been done so far that it can be a leading indicator of the presence of COVID-19 in a community. More than that, the changes in COVID-19 levels in the wastewater have been shown to track the changes in COVID-19 rates in the community,” he said.

The Maine CDC began its municipal testing program last month at 13 sites across the state. Now, twice a week, workers at the Lewiston-Auburn Water Pollution Control Authority take a wastewater sample that’s shipped off to the Maine CDC’s vendor, Biobot Analytics. Biobot analyzes the samples and sends the results to the Maine CDC, which then posts the reports to its COVID dashboard.

“It’s very straightforward from our end,” LAWPCA general manager Travis Peaslee said Wednesday. The facility serves the cities of Lewiston and Auburn.

“We’re already sampling every day and basically pour a little volume off of ours and drop it in a container,” he said.

The most recent report, which was published earlier this week, shows that the prevalence of COVID in L-A’s wastewater decreased at the beginning of the month. Testing is still in its early stages, however, and Shah said it will take several weeks of testing to establish a baseline.

“With that as an upfront disclaimer, the data are encouraging and track what we’ve seen with respect to things like hospitalizations, as well as ventilator and ICU usage, which is to say a lessening of the disease burden right now in Maine,” Shah said at a media briefing Wednesday.

Statewide, the number of individuals hospitalized with COVID in Maine hospitals has dropped 30% in less than a month. Hospitalizations hit an all-time peak of 436 on Jan. 13.

That pattern is not universal across all sites, Shah said, which is “to be expected for a large state.”

Given a few more weeks of data, Shah said, “then we’ll be able to really tell on a week-by-week basis what’s changing.”