Wastewater monitoring for Covid-19 is picking up steam across the US

In September 2020, the US Centers for Disease Control and Prevention launched the National Wastewater Monitoring System, investing millions of dollars in an effort to coordinate and develop programs that track coronavirus in samples collected in sewage systems.

Participation in the program has steadily increased since its launch. But what is generating interest now, and leading to the biggest bump yet, is the shift in clinical trial strategies in the US, said Amy Kirby, a microbiologist who directs the CDC’s wastewater program.

With the increasing prevalence of home testing for COVID-19 and declining public interest in testing in general, fewer case data are being officially reported. Local health departments are “recognizing that clinical surveillance won’t have as much information about what’s going on in the community,” she said.

“Wastewater is a non-intrusive way to get that early, reliable information of what’s going on in your community,” Kirby said.

The CDC launched a national public dashboard tracking Covid-19 wastewater data in February, and the number of participating sites increased from about 400 to nearly 700 sites in the two months since.

In that same time, the daily average of reported Covid-19 tests dropped by two-thirds, according to data from the US Department of Health and Human Services.

The CDC’s wastewater program has enough money to sufficiently cover programs in all 50 states and an additional 14 jurisdictions, with guaranteed funding through 2025.

There are 33 states currently funded through the agency’s epidemiology and laboratory capacity cooperative agreement, and another 14 that have a commercial testing contract, but the CDC expects all 50 states to be represented in the network by next year. Grant applications are now in process for the 2023 funding.

Wastewater surveillance is not a new public health tool, but it was far from mainstream before COVID-19.

Local health departments are still figuring out how to make better use of this tool. They have questions about how to partner with utilities to collect samples in the first place, as well as how best to analyze and interpret the resulting data and more, said Deise Galan, principal analyst with the National Association of County and County Health Officials. cities. public health preparedness program.

Enough questions have come in from members that NACCHO recently launched a mentoring program that has so far paired a local jurisdiction with a lot of experience in wastewater policing with a couple others just starting out.

About a dozen local health departments have applied to be a part of this mentoring program, and it has sparked the interest of many more who have reached out for more information.

β€œIt has become something that has not only caught the desire of local health officials, but also their elected officials as something that they can actually implement and use not only for SARS-CoV-2, but for other pathogens as well.” Galan said. .

Wastewater is a hyperlocal monitoring tool, providing information only about the specific community served by the participating wastewater treatment plant. But experts say there is clear value in incorporating as many sites as possible.

“The fact that we get really good data on that community is a strength, but also a weakness because we need to get as many sewage systems as we can to do these tests to get a more complete picture,” Kirby said.

CDC took about a year and a half, from the program’s launch in September 2020 to February 2022, to work on how to better standardize and present the data they had been collecting in a national dashboard.

At this time, the data on the dashboard is limited. A map shows the relative change in coronavirus detection levels over a single 15-day period, with previous trends in percentage change only available by downloading a large dataset.

But in the coming weeks, the CDC plans to update its national wastewater dashboard with more information not only about how levels change from week to week, but also how the absolute level of coronavirus detected in a sewer compares to other points of collection. the pandemic. They also plan to include an option to view trends over time for each site.

How the next variant of the coronavirus could emerge

“Our approach is to use this system as an early warning of surges in the community. And we want that early warning system to be as early and sensitive as possible,” Kirby said.

This high sensitivity can create “noise” in the system, he said. But with variants like BA.2 selecting in the US and others potentially looming on the horizon, they prefer to play it safer.

“We’re working closely with our state and local public health officials to make sure they’re interpreting the data correctly to answer your questions. We’re monitoring those increases until we’re convinced they’re just noise or we see they’re real increases.” And we have to move on them.”

More participants provide more opportunities to share knowledge about a public health tool that many are also beginning to become familiar with.

“Why are we going to reinvent the wheel, if there are other places that have been able to successfully implement this program?” Galan said. “Locally, we can have that peer-to-peer exchange and collection of best practices.”

Putting it all on a national dashboard allows local health departments to explore what’s happening in similar places, said Chelsea Gridley-Smith, director of environmental health for NACCHO.

“Local health departments know who they see as peers. So a rural county may look to Chicago for guidance, but not for similarities. But if they can compare themselves to another rural county, they might find more and more programs like themselves,” he said.

“Those are the places where having everything compiled into one CDC location allows us to explore the possibility of expanding the partnership outside of a single state with the similarities in county size and jurisdiction size and type of population and infrastructure configuration.

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