BOSTON (CBS) — Wastewater is helping to track the presence of COVID-19 in Massachusetts. “COVID-19 is shed into feces which makes its way into the sewer and eventually the wastewater treatment plants,” said Kyle McElroy, a research scientist at BioBot.

The Massachusetts Water Resources Authority is part of a pilot study looking at wastewater. It has a contract with Cambridge-based Biobot to process the samples.

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Samples are taken at the Deer Island Treatment Plant three times a week. The wastewater tested flows in from 43 communities around Boston.

“It’s a very good measure of how much infection there is in the community,” said Dr. Ashish Jha, the Dean at Brown University’s School of Public Health.

Coronavirus in wastewater samples (Massachusetts Water Resources Authority)

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He said the MWRA data showed a huge COVID spike in the spring and it’s showing a spike once again.

According to Jha, wastewater testing picks up the virus from people who have symptoms and from people who don’t.

“In that way at our population-level a much more sensitive measure for how much infection there is than the testing that we’re doing where we know we miss a lot of asymptomatic people,” said Dr. Jha.

Gloucester is also testing its wastewater. The city’s health director Karin Carroll said it helped them monitor a recent uptick in cases. They plan to use the data as they make decisions going forward.

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“I think as we move into the winter with cares it’s will be helpful in knowing should a community pull back a bit from say Phase 3 Step 2, should we go back to Step 1,” said Gloucester Health Director Karin Carroll.