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South Carolina saw nearly 16,000 new cases of COVID-19 and seven new deaths, according to the weekly update from the Department of Health and Environmental Control. File/Gavin McIntyre/Staff

Those who live in South Carolina's major cities will again be able to see surveillance for the virus that causes COVID-19 that has been missing, for months in some cases.

Wastewater testing data is now available for Charleston, Columbia, Greenville and Myrtle Beach. In some places, it shows a decline, which could soon mean a decrease in cases, said an expert at Medical University of South Carolina.

Routine testing of sewer samples can show how much of the virus is currently circulating in the community. Because it does not require anyone to go in for individual testing, and infected people can shed virus days before they begin to develop symptoms, it can be an important and reliable early indicator for community spread, said Dr. Michael Sweat, director of the MUSC COVID-19 Epidemiology Intelligence Project. 

The rise, and now decline, among virus levels in certain areas seems to precede the rise and fall in actual cases, he said, but it needs to prove itself out over time.

"The (wastewater) trend is picking up changes quicker than what is happening with the testing," he said. "If this all holds up, it is really a great advance because we get several weeks of an earlier warning system in place."

The testing had not been publicly reported for many areas of South Carolina, including its major cities. That data began appearing again last week on the Centers for Disease Control and Prevention National Wastewater Surveillance System. Data as of mid-July was available for Charleston, Columbia, Greenville and Myrtle Beach, among others.

It showed a decent increase in virus levels over a two-week period: 14 percent in Columbia, 19.6 percent in Charleston, 25.6 percent in Myrtle Beach and a 2.5-fold increase in virus levels for Greenville, according to an analysis by The Post and Courier.

For Sweat and others who had complained about the lack of that data for those areas, it was a welcome sight.

"It’s remarkably helpful, partially because we have been relying so heavily on the official testing data," he said.

Those numbers are widely acknowledged to be a severe undercount of actual infections because so many of those who are sick use a home test for diagnosis. Those results do not go into a public database.

"Having another metric like (wastewater virus levels) that is particularly unbiased is very, very valuable," Sweat said.

The 15,811 new cases reported Tuesday by the S.C. Department of Health and Environmental Control represent a 5 percent increase over the previous week. Last week showed a 9 percent decline in new cases compared with the week prior, figures showed.

But virus levels, at least for the Charleston area, are beginning to decline in the wastewater data and infections may soon follow.

"We’ve been predicting a decline," Sweat said. "The (case) numbers have gotten pretty high, and they have flatlined recently."

As of Aug. 6, cases in the Charleston area dipped as expected.

"Sure enough, the case rate dropped, and it looks like the wastewater data predicted that several weeks in advance," Sweat said.

Case numbers from DHEC

The agency reported nearly 15,811 new COVID-19 cases and seven deaths related to the virus from July 31-Aug. 6.

Statewide numbers

New cases reported: 15,811

Total cases in S.C.: 1,637,108

New deaths reported: 7

Total deaths in S.C.: 18,215

Percent of ICU beds filled (with COVID-19 and other patients): 62.5 percent

Percent positive: 24.9 percent

S.C. residents vaccinated

In South Carolina, 60.7 percent of people who are eligible for the vaccine have received at least one dose, and 52.7 percent of eligible residents are considered fully vaccinated against the coronavirus.

These numbers reflect all eligible state residents, including young children. The latest data from DHEC shows 22.2 percent of children ages 5-11 have at least one vaccine dose and 2.2 percent under age 5 had received a shot.

Hospitalizations

Of the 587 COVID-19 patients hospitalized as of Aug. 6, 78 were in the ICU and 25 were using ventilators.

What do experts say?

"COVID is still spreading at high levels across most of the U.S. Staying up to date with your vaccination reinforces your protection from severe disease, which is especially important if you're 50 or older or are medically vulnerable." — Tom Frieden, former CDC director 

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Reach Tom Corwin at 843-214-6584. Follow him on Twitter at @AUG_SciMed.

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