After being at low levels for months, coronavirus prevalence doubled at both Portland Water District wastewater treatment plant locations this week.

The levels, measured in copies of coronavirus per liter of wastewater, were at about 1 million at the East End plant as of Friday, and 1.3 million at the Westbrook plant. That’s far below levels seen in late January and early February, when virus prevalence was about 2 million or higher, or at the peak of more than 5 million in late December and early January.

But even compared with a week to 10 days ago, levels have doubled at the Portland Water District plants. Wastewater testing is considered a leading indicator of the presence in communities of the coronavirus, the virus that causes COVID-19.

Results were mixed at other sewage plants where wastewater testing is occurring. Brunswick and Presque Isle have experienced sharp decreases this week, while Bangor also declined slightly after seeing its numbers vary significantly over the past week. Lewiston-Auburn recorded a steep increase this week, while York showed a slight increase.

Dr. Yolanda Brooks, an assistant professor of biology at St. Joseph’s College in Standish who did the coronavirus testing for Yarmouth’s wastewater program, said the increases in Portland have persisted over at least three testing periods, which is a “little concerning” even though levels are still far below what was seen in January.

Brooks said it’s hard to know what is driving the increases, as there could be other reasons besides more people contracting the virus. For instance, Portland is a hub for workers, and with more employees returning to the office, that could be impacting the volume of people using Portland’s wastewater system.


It’s also the beginning of tourist season, and more visitors could be using the system, she said. The recent K-12 spring break also could have affected the numbers.

Brooks said another dynamic is that in smaller systems, the numbers bounce around more. Even though Portland is Maine’s largest city, the wastewater system is still small compared to those in major urban centers such as Boston and New York.

“There’s more variability in smaller systems,” Brooks said. “Fewer people getting infected and shedding the virus can affect the measurements in smaller systems.”

Despite the increases in Portland, Brooks said that with high vaccination rates and Maine having recently gone through the omicron wave, she doesn’t anticipate a return to the state’s winter virus surge.

Maine reported 470 new cases of COVID-19 on Friday, along with one additional death. Since the pandemic began, Maine has recorded 244,062 cases of COVID-19 and 2,283 deaths.

Hospitalizations increased to 143 on Friday from 132 on Thursday. There were 34 patients in critical care Friday and five on ventilators.


Maine’s COVID-19 hospitalizations had remained nearly flat since mid-March, hovering between 90 and 100 patients before rising sharply this week. The current total is still down dramatically from this year’s peak of 436 hospitalizations on Jan. 13.

Unvaccinated people represented roughly two-thirds of the COVID-19 patients treated in Maine hospitals from when vaccines became readily available through April 15, according to the Maine Center for Disease Control and Prevention website.


Meanwhile, Moderna announced Thursday that it is seeking emergency use authorization for a COVID-19 vaccine for children ages 6 months through 5 years old. No COVID-19 vaccine for toddlers and infants has been approved despite adults having access to vaccines for about a year. A vaccine developed by Pfizer was approved for children ages 5 to 11 in the fall.

On Friday, the U.S. Food and Drug Administration said it plans to convene a panel of vaccine experts in June to review applications from both Moderna and Pfizer for child vaccines, The Associated Press reported. The dates are not final, and the FDA said it will provide additional details as each company completes its application.

The Moderna vaccine proved effective in a two-dose regimen given 28 days apart, according to a Moderna study of 6,700 children.

“We are proud to share that we have submitted for authorization for our COVID-19 vaccine for young children,” Moderna CEO Stéphane Bancel said in a statement. “We believe (the vaccine) will be able to safely protect these children against SARS-CoV-2, which is so important in our continued fight against COVID-19, and will be especially welcomed by parents and caregivers.”

The vaccine’s effectiveness is 51 percent for children ages 6 months to under 2 years, and 37 percent for ages 2 to 6, according to a company statement.

“That means that you’re going to reduce your chances of getting disease by about a half,” Dr. Paul Burton, Moderna’s chief medical officer, told NPR in an interview. “That’s very important for these kids.”

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