Sewage testing program to help keep tabs on COVID

Apr. 27—Testing for COVID-19 is moving from pharmacies and clinics to your local sewage treatment plant.

Though deaths and hospitalizations are far below the terrifying heights of December and January, and Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said this week that the United States is transitioning out of the pandemic, public health officials still need information about where COVID-19 is spreading to keep ahead of the virus.

Enter wastewater testing. Federal funding approved by the Executive Council last week will help a University of New Hampshire program expand off campus, and begin monitoring levels of the coronavirus in sewage in up to 25 cities and towns around the state.

Paula Mouser, the associate professor of civil and environmental engineering at the University of New Hampshire, who has been running the university's wastewater testing program, said she's pleased to see wastewater testing finally ramping up in New Hampshire.

Wastewater testing — testing sewage samples from water treatment centers or even manholes — has been able to show where COVID-19 is spreading before positive PCR tests start coming back.

The sewage-based tests don't show which individual people have COVID-19 — rapid tests or PCR tests are still needed for that — but researchers can see the levels of virus spiking in sewage even before people show symptoms, and help public health officials figure out which way the trend is going.

Mouser said the University of New Hampshire has been using wastewater testing to help predict which residence halls may experience an outbreak of COVID-19.

The new funding will provide Mouser's team the resources to expand testing to cities and towns. Cities, towns and water districts will be able to opt into the program, which will help give local health departments a little advance warning about any COVID surges to come.

Machines will regularly collect samples from local facilities, and then those samples will be taken to university labs for testing.

"The wastewater is an unbiased indicator of how prevalent COVID is in a given community," Mouser said. "It is directly correlated to the prevalence of the disease in the sewer-shed."

Sewage testing picks up virus from everyone in the area, not just full-time residents — which will be key as the summer tourism season brings more out-of-towners.

Mouser said her team has been running tests in Ogunquit, Maine — picking up results not just from the town's residents, but from tourists and weekenders who may also be carrying the virus, which is another advantage of using wastewater for surveillance testing.

Other communities, including towns and cities in the Boston area and Burlington, Vt., have been using data from wastewater testing since early in the pandemic to help inform public health policies like indoor mask requirements. The state of Maine also implemented a wastewater testing program in January.

"It's really surprising that it's taken this long for this to be applied at a wider scale," Mouser said.

More data needed

But the new wastewater monitoring program comes as other ways of figuring out how prevalent COVID-19 is in a community have become less reliable.

This spring, public health officials are facing a dearth of data because more people are using at-home COVID-19 tests — and the results of at-home tests are not reported to state health officials.

The number of PCR tests has plummeted since January. At the beginning of this year, more than 15,000 people per day were getting the nasal-swab tests at state sites, pharmacies and local clinics. On an average day last week, fewer than 4,000 people got PCR tests in New Hampshire.

With fewer people now taking those PCR tests, in favor of at-home rapid tests or choosing not to be tested at all, health departments have less information about just how prevalent COVID-19 is right now.

"We have this missing piece of information about infection because now people can self-diagnose," Mouser said. "Moving toward wastewater surveillance gives us a good idea where we have higher spread or higher prevalence of COVID-19 across the state."