Cities Turn to the Sewers to Track the Prevalence of Covid
The Greater Augusta Utility District in Maine last week began collecting wastewater samples to test for Covid-19, a grant-funded program that runs through October. Greater Augusta Utility District
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Testing wastewater samples can give public health officials a heads up that an outbreak is looming, as people infected with SARS-Cov-2 shed the virus in their feces weeks before they begin showing symptoms.
As Covid-19 cases continue to rise and test results lag, officials in Augusta, Maine are tapping an unexpected source for information about the local spread of the virus: sewage.
Research has shown that people infected with SARS-Cov-2, the virus that causes Covid-19, shed the virus in their feces before they begin showing symptoms. Analyzing wastewater samples for the presence of the virus’ genetic material, known as RNA, can predict the scope of community infection rates up to two weeks before a positive test result, allowing public health officials to prepare in advance for a potential surge of cases.
“The thought is that this could be an early warning system for decision makers regarding whether or not there’s going to be an uptick in cases from these people who are currently not exhibiting symptoms,” said Phyllis Arnold Rand, water quality coordinator for the Greater Augusta Utility District, which serves about 19,000 people in five communities in Kennebec County. “Right now, we’re hearing in the news that there’s going to be another wave. But there is no warning system for that—the only way we find out is, unfortunately, by the number of new cases. If this type of surveillance works, it could help them know for sure.”
Last week, automatic sampling machines at the wastewater treatment facility began collecting 300 milliliters of sewage from every 1,000 gallons that flows into the plant over a 24-hour period. The samples are collected by suction, Rand said—pulled directly from the intake channel into a refrigerated jug, then transferred later to test tubes.
The tubes are then mailed to Biobot, a Massachusetts-based technology company, for analysis, which is compiled in a weekly report that will “estimate the prevalence of Covid-19” in the local population. The first report is expected this week and will establish a baseline for comparison in future weeks, Rand said.
The program, which runs through the end of October, is funded by grant money included in the last federal coronavirus relief package approved by Congress. Keith Luke, the city of Augusta’s economic development director and a non-voting member of the utility’s board of trustees, first learned of the technology from an NPR story but dismissed it as a local possibility because of the high cost.
“When the grant funding became available, it’s something we reconsidered,” said Luke, who wrote the application for the grant, which covers the entire $24,480 cost of the program. “Our general manager at the utility district was very supportive, because we could clearly see the benefit of having this information available.”
The test results will add context to the large amount of data that officials are already using to keep tabs on the extent of the pandemic locally, including confirmed case counts. Like the rest of Maine, Kennebec County has had a comparatively low number of cases (as of Thursday, the county reported a total of 162 over the pandemic).
“The real value for this information isn’t as a single data point, but as we chart it in the coming weeks or months to know whether there is an elevated presence or a declining one or none at all,” he said. “We don’t know the answer to that question right now because we have been limited to testing data, done on an individual basis that is reported out in ways that aren’t immediately apparent to municipal decision makers.”
The data will help inform public health decisions, such as rolling back reopening plans if an outbreak is looming or relaxing restrictions on large gatherings if several weeks go by with no significant increase. Like other Covid-19 data, test results will be available to the public as they come in, Luke said.
“If I know the prevalence of the virus in the community is very, very low, my ability to eat my lunch or dinner at a restaurant without dreading the possible outcome is going to be enhanced,” Luke said. “I think people could look at this information as a tool they can use to make better decisions about how they are going about living their lives.”
Cities have previously used similar wastewater testing technology to assess the local scope of the opioid epidemic, and a growing number of communities—from Montana to Texas to Tennessee—are now also tracking Covid-19 via their sewage systems. Since Augusta applied for its grant funding, more companies are offering the testing, including several in Maine, which could make it easier—and potentially less expensive—to continue sampling in the future, Luke said.
“We’re all on the cutting edge of this,” he said. “It’ll be an interesting experience in just the next few weeks to see what the information says and what we can learn from it.”
Kate Elizabeth Queram is a staff correspondent for Route Fifty and is based in Washington, D.C.
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