Staff reports | A program that measured levels of COVID-19 in wastewater from the Charleston area proved an invaluable tool ahead of the Delta surge in 2021, but the program quietly went by the wayside as at-home testing made infection reports more and more unreliable.

According to the state Department of Health and Environmental Control, 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, especially as the nation inches toward another surge caused by the BA.2 subvariant.

With the rise of at-home testing, infection rates are being undercounted across the country as health officials grapple with understanding the impact of the BA.2 subvariant. While infection rates can be useful indicators, some federal officials and public health experts say they’re increasingly focused on other metrics, such as hospitalizations and wastewater tracking. 

“The systems that we’ve used to detect cases — whether they be testing, surveillance, how we report out information — I think is very different today than it was even 12 weeks ago,” Michael Osterholm, who leads the University of Minnesota’s Center for Infectious Disease Research and Policy and advised President Biden’s transition team, said in a statement.

Meanwhile, the water treatment facility at Plum Island, which covered the Charleston area’s testing, sent its last sample for COVID testing in August 2021, according to 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 – amidst an apparent upswing in local wastewater virus detection. No one City Paper has spoken with, including Saia, has been able to explain the disconnect.

“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.”

Latest COVID-19 data

In South Carolina, the state Department of Health and Environmental Control (DHEC) transitioned to weekly reporting of new COVID data last month, with Tuesday’s update being the most recent of reports including data taken from April 10-16.

State health officials on Tuesday reported 1,521 total new cases of COVID-19, with 996 confirmed, and seven total new deaths, six of which were confirmed. As of April 18, 90 COVID-19-positive individuals are hospitalized, and nine COVID-19-positive individuals are ventilated.

No positivity rate was reported by DHEC.

  • Percentage of S.C. residents age 12+ with at least one vaccine: 67.1%
  • Percentage of S.C. residents age 12+ who have completed vaccination: 58%
  • Percentage of S.C. residents age 5-11 with at least one vaccine: 20.2%
  • Percentage of S.C. residents age 5-11 who have completed vaccination: 16.4%

For more information, visit the S.C. SCDHEC COVID-19 dashboard.