The Yarmouth Community Coronavirus Task Force is concerned about findings from recent wastewater testing that showed a sharp increase in the presence of SARS-CoV-2, the virus that causes COVID-19.
Testing of Yarmouth wastewater from Aug. 26 to Sept. 21 found levels of SARS-CoV-2 to be nearly as high as those seen in April 2020, indicating a potential increase in COVID-19 cases in town.
The implication of the higher test levels are unclear, however.
“There has been a surge of COVID cases in Maine and the CDC has had a backlog when it comes to processing the cases that are coming in,” task force member Roy Gibson “Gib” Parrish said. “It’s hard for us to say where things stand right now.”
As of Oct. 3, a total of 401 confirmed cases of COVID-19 had been reported in Yarmouth. As of Monday, there had been a total of 15,553 confirmed cases in Cumberland County and 67,659 confirmed cases statewide. There was a spike in statewide cases in mid-September.
The increase in the August-September 2021 samples could be caused by a number of factors, Parrish said: a change in the proportion of vaccinated people in Yarmouth; the emergence of the Delta variant, which could cause a change in the concentration of the virus; breakthrough cases that may be asymptomatic; or a lack of testing.
Since wastewater testing resumed in August after a two-month break, the levels of the virus in the samples have been consistently high, Parrish said.
“The tests we were doing in late May and early June essentially had undetectable levels of the virus,” said Parrish, who has training in pathology and has worked in public health for most of his life.
The current levels are almost equal to what they were in the early days of the pandemic, according to Yolanda Brooks, assistant professor of biology at Saint Joseph’s College in Standish, which tests the wastewater samples.
Brooks said from December 2020 to June 2021, a 10% increase in the virus detected in wastewater samples was associated with a 2.49% increase in COVID cases prior to and the week of the wastewater samples being taken.
“Currently, from what we have now, adjusting for flow rate and recovery, the concentration of wastewater is what we were seeing around April of last year,” Brown said.
The correlation between the COVID-19 levels in the wastewater and the number of cases in Yarmouth reported to Maine CDC had been “very good” from September 2020, when the weekly testing started, to June 2021, Parrish said.
The earlier analyses showed “the wastewater and the number of cases track together quite well,” he said.
Wastewater samples are tested in Yarmouth once every week. Results are available every Friday at bewellyarmouth.org.
Parrish said the task force will continue to put advisories out to the community whenever the levels of SARS-CoV-2 are elevated.
The results of wastewater testing in Yarmouth from Aug. 26 to Sept. 28, and the number of COVID-19 cases in Yarmouth, with Sept. 27-Oct. 3 unavailable.
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