The Plum Island Wastewater Treatment Facility has abruptly discontinued its COVID wastewater monitoring program | Photo by Rūta Smith

A program that measured levels of COVID-19 in wastewater from the Charleston area proved an invaluable tool ahead of and through the Delta surge in 2021, but the program has quietly gone by the wayside, worrying health providers ahead of an expected surge in infections from the BA.2 variant. 

The testing program asked wastewater treatment facilities to send samples to the state Department of Health and Environmental Control (DHEC). The agency would analyze the sample for genetic traces of COVID-19 and send the data to the federal Centers for Disease Control and Prevention (CDC). But the facility at Plum Island, which covered the Charleston area, sent its last sample in August 2021, according to the Charleston Water Service Public Information Administrator Mike Saia. Yet the most recent data reported by the CDC from the facility is from March 27, 2022. No one City Paper has spoken with, including Saia, has been able to explain the disconnect.

“While wastewater surveillance has the potential to be a valuable tool for early detection of an increase in the spread of the virus, the current geographic areas from which wastewater is being sampled is a limitation in our ability to detect potential increases in the population as a whole,” DHEC told the City Paper in a statement. 

The coronavirus is known to be shed in human waste and present in domestic sewage. Because of this, DHEC’s Bureau of Water partnered with the University of South Carolina (UofSC) and the Medical University of South Carolina (MUSC) to conduct a pilot study of COVID levels in wastewater throughout the state. 

According to DHEC, the study initially found that the amount of the virus detected in raw sewage can serve as a reliable and early indication of infection in a population, predicting surges and measuring local impacts before clinical cases are generally reported. The tool could be invaluable, according to Dr. Michael Sweat, director of the MUSC’s Center for Global Health.

“The huge value of wastewater testing is in the speed of reporting,” Sweat said. “It gives you an early warning, and it’s unbiased. With individual testing, it’s always been biased. A lot of people don’t get tested, and many more are asymptomatic. Those biases have only gotten worse with the advent of home testing.

“We’re in a mode now where a lot of people are tuned out, but there’s a lot who really do need the warning — they’re immunocompromised, they’re vulnerable, maybe the vaccine didn’t work well for them — so just besides the general population, many in particular would benefit from early warnings.”

Plum Island’s facility was run in partnership with UofSC, but no former project leaders have responded to multiple requests by City Paper for comment. 

Saia said the Charleston Water Service was told by a representative from DHEC that their samples “were no longer needed.”

DHEC by press time had not responded to City Paper requests for comment on Saia’s asssertion.

According to state epidemiologist Dr. Linda Bell, DHEC has nine facilities that have reported wastewater data to the agency on a regular basis, including facilities in Georgetown, Richland and Lexington counties. The CDC’s tracker, however, has every facility in South Carolina marked as having submitted “no recent data.”

Expanding the program has proven difficult, Bell said, because DHEC doesn’t mandate participation, and national supply issues have made it difficult for new programs to launch. But local health-care providers say the program is a powerful tool in measuring and predicting outbreaks of not only COVID-19, but many infectious diseases, and is worth the effort.

“Having such data would be invaluable to being able to have an early warning for future outbreaks, including BA.2,” Sweat said.

Other states are far ahead of South Carolina. Colorado, for example, began disease surveillance in its wastewater five years ago, so transitioning the program to COVID was simple. Its program showed clear spikes ahead of and during the initial Alpha outbreak, and waves of Delta and Omicron. The program has generated national coverage in publications like The New York Times and National Public Radio. 

Bell said while South Carolina’s program has potential to be an early warning system, it’s still in the formative stages for a number of reasons.

“We have a relatively small number of facilities participating, there are some issues on the national level with the testing supplies to run these programs, and there are also additional things being worked out to match what we detect in wastewater with circulation in the community,” she said.

“We don’t have any control over these facilities, but in terms of the method itself, there’s potential here and at the national level to detect pathogens in sewage. We’re looking at building the capacity to have more widespread surveillance with this project. But that relies on sampling reform. Certain lab equipment has to be set up, and the testing material has to be made more readily available.”

This method of COVID surveillance would be supplementary to others. But without a more robust and widespread program, the primary surveillance tool remains reported cases and hospitalizations. 

“This is just one component of our surveillance system, and until we get the necessary capacity, we will still have to rely on diagnostic samples reported to the health department,” Bell said.

But that comes with its own complications. As at-home testing has grown more popular, accurate case counts have been more difficult to get, since positive test results from over-the-counter test kits often go unreported. 

When it comes to getting the program to where it needs to be, Bell said DHEC’s hands are tied. “We rely on these treatment facilities to participate,” she said. “We are not actively enrolling them or mandating participation. We don’t have control over the supplies … this isn’t the same as required reporting from health-care providers who get a COVID sample from an individual.” 

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