Expert Panel Urges US to Strengthen Wastewater Surveillance

Citing the usefulness of wastewater monitoring in detecting COVID-19 surges, an expert panel has presented a plan for how the Centers for Disease Control and Prevention (CDC) could build upon the current spotty surveillance network and expand it into a nationwide early warning system for new or resurgent infectious diseases.

The CDC asked the National Academies of Sciences, Engineering, and Medicine (NASEM) to create a framework for the agency to beef up the National Wastewater Surveillance System (NWSS), which began in 2020 as a pilot program in response to the emerging COVID pandemic.

The program — which examines untreated sewage for RNA from the SARS-CoV-2 virus — was initially carried out in eight states with mostly volunteers. The NWSS has since spread and now has more than 1250 sampling sites, covering more than 133 million Americans. Sampling is conducted at treatment plants that serve as few as 100 individuals to as many as 4 million people.

But not every wastewater treatment site or public health agency in the United States participates, and not every home or building is connected to a wastewater treatment plant. Some 16% of the US population is not connected to a plant from their home. And, aside from scientific challenges and privacy concerns, there are political obstacles and funding shortfalls that present barriers to expansion.

“One of the challenges is to move this to a sustainable funding model,” said NASEM panel chairman Guy Palmer, DVM, PhD, in a press briefing held Thursday.

The current NWSS has largely been financed through COVID-19-related emergency funding.

It is up to Congress to determine whether it wants to allocate more stable funding for a surveillance system, noted Palmer, the Jan and Jack Creighton Endowed Chair in Global Health at Washington State University in Pullman, Washington.

A More Perfect Alert System

Wastewater surveillance has been used globally to help detect polio. In the US, in addition to being used to detect SARS-CoV-2 and its variants, it was employed in 2022 to detect polio and mpox outbreaks.

Palmer said that trolling sewage for pathogens can be a reliable way of detecting when a virus — or a new variant — might be running rampant in a particular location. For instance, with so many people now testing at home for COVID, results are rarely reported to public health agencies, leaving a knowledge vacuum.

But health authorities can sample wastewater at regular intervals, eliminating some of the bias that comes with relying on test data, said Palmer.

The NASEM committee noted that current wastewater sampling has not reached its full potential because of the lack of full geographic coverage and the inability of some localities to participate, owing to lack of funding or staff time.

The committee recommended that CDC present to state and local health agencies evidence of the usefulness of wastewater sampling in comparison with other methods and help out with dedicated funds.

Some locales have not participated because of the prevailing political winds, said panel member Michelle M. Mello, PhD. “There is not the same appetite across the country for taking action on the basis of signals that there’s a problem,” said Mello, a professor of law and health policy at Stanford University. “There’s more political will in some places than others.”

To improve the current system, the panel urged CDC to develop a transparent process for selecting pathogens for surveillance and that those targets be of “public health significance.” Surveillance of targeted viruses or bacteria should also provide data that health authorities can use to take action.

The committee also recommended that CDC create an ethics advisory panel to address how the surveillance data will be shared. It also said that there should be a “strong firewall” that precludes use of wastewater data by law enforcement.

Need for “Sentinel” Sites

Given that many pathogens emerge in other countries and are then brought into the US, the NASEM panel recommended that certain sites be monitored more frequently.

Among those: major international airports and ports and international athletic events, such as soccer’s 2026 World Cup, which will be held in cities in the US and Mexico.

In late December, the CDC said it was considering sampling wastewater on international aircraft to assess whether travelers were bringing COVID into the US.

The committee also recommended increased sampling at zoos and wildlife parks to detect the potential spread of zoonotic diseases.

Alicia Ault is a Saint Petersburg, Florida–based freelance journalist whose work has appeared in publications including JAMA and You can find her on Twitter @aliciaault.

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