New York City’s Department of Environmental Protection looks to extend its efforts tracking coronavirus through the sewers after completing its initial pilot program at the end of last year. The wastewater program has already shown promise as a public health tool, particularly in helping labs that do genetic sequencing to detect emerging variants of COVID-19.
But officials made it clear at a City Council oversight hearing on wastewater surveillance Friday that they’re still figuring out exactly how to use the information that’s gathered from New Yorkers’ urine and feces to inform public health decisions. Studies have shown wastewater can give a rough and early signal of rising coronavirus levels in upstate communities. For now, researchers don’t think it can replace testing at New York City clinics.
“The data we collect at the [Department of Environmental Protection] is not a crystal ball,” Pam Elardo, deputy commissioner of the agency, told Council members in her hearing testimony. “The wastewater data alone cannot be used to precisely predict infectious waves that are coming or dictate how the city should respond.”
Councilmember Lincoln Restler, who represents parts of Brooklyn, asked city officials whether wastewater surveillance can stand in for traditional testing at times when people aren’t getting swabbed as frequently.
The level of coronavirus detected at one of the city’s wastewater treatment plants does tend to correlate with the number of cases in a given area, Dr. Celia Quinn, deputy commissioner of the Division of Disease Control at the city health department, confirmed at the hearing.
But Quinn emphasized that wastewater surveillance cannot yet be used to infer the exact number of cases on its own because the amount of virus someone sheds when they’re infected with COVID-19 can vary widely from person to person — even throughout the course of an infection.
“We’re still really learning about what the data means that’s coming from the wastewater and how to interpret it in the context of the data we have citywide,” she said.
Still, Elardo said her agency had made great advancements in its ability to sample and test the city’s wastewater for coronavirus since launching the initial pilot program in August 2020. In addition to testing wastewater locally, the DEP is also sending samples to the Centers for Disease Control and Prevention, which Elardo said has allowed for independent verification of the accuracy of the city’s data. The CDC recently launched an online portal for the public to track wastewater surveillance in participating counties.
Wastewater testing can also give scientists clues as to how the virus will evolve, said Dr. John Dennehy, a virologist at Queens College who testified at the hearing about the work his lab has done in partnership with the DEP.
Dennehy co-authored a recent paper published in Nature Communications that looked at “cryptic variants” of the coronavirus — that is, variants that have shown up in New York City’s wastewater but haven’t been found in human testing samples.
Different theories exist on the source of the variants, and Dennehy and others hypothesize that these offshoot viruses originate with people who are immunocompromised and can have monthslong infections with the coronavirus, allowing the germ time to mutate. Dennehy said he’s “very much concerned” that one of these cryptic variants will give way to the next major strain of the coronavirus that does circulate among humans.
Elardo said she hoped to continue the wastewater surveillance program indefinitely, assessing its utility at regular intervals. In February, DEP and the city’s health department released a summary of the pilot program. It reported that the 21-month initiative was funded by DEP at a cost of $521,333 and run through its Bureau of Wastewater Treatment, but that it “entailed significant demands on DEP human resources.”
To relieve this financial strain, the CDC took over the costs of testing the wastewater samples in January as part of a one-year extension for the program. New York Gov. Kathy Hochul is also proposing $5 million per year in her state budget to expand wastewater surveillance through fiscal year 2025.
“The advances have been remarkable,” Elardo said. “However, the tools are still developing, and we still have a lot to learn.”