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2023 Covid peak easing in some regions, wastewater analysis suggests


Wastewater data suggests the recent rise in Covid cases may have peaked, at least in some areas.

Biobot Analytics, a company that tracks wastewater samples at 257 sites across the country, said current average Covid levels in the United States are about 5% lower than last week.

“All fingers crossed,” said Cristin Young, an epidemiologist at Biobot, “this wave is stagnating and may decline.”

As data from the Centers for Disease Control and Prevention shows an increase in Covid-related hospitalizations and deaths, sewage may indicate what’s to come.

After a surge in mid-to-late summer, the CDC’s Covid sewage monitoring now shows declines in mid-Atlantic states, like Virginia and Maryland.

The findings are supported by surveillance in North Carolina, said Jessica Schlueter, an associate professor in the department of bioinformatics and genomics at the University of North Carolina at Charlotte. His lab is responsible for testing 12 sites across the state.

The increase in Covid wastewater samples over the past six months “seems to be peaking and starting to decline”, she said.

Wastewater collection sites in the Midwest and Northeast, however, are showing a steady increase in Covid spread.

The increases that coincide with the start of the school year have become normal based on the past three years of Covid activity, but are not expected to last long, said Amy Kirby, who directs the CDC’s wastewater monitoring program.

“We’ve seen enough data over the years to know that around the time school starts back up, we’ll start to see increases,” she said, “that will level off and then go back down” before a new winter surge.

Another monitoring system called WastewaterSCAN, which tracks 183 sites in 36 states, is slightly more conservative in its analysis of the latest Covid wastewater data.

“What we’re seeing now is kind of a flattening,” said Marlene Wolfe, an assistant professor of environmental health at Emory University and director of the WastewaterSCAN program. “We haven’t really seen a real slowdown yet.”

Like the CDC data, she said, the WastewaterSCAN results indicate a current increase in the spread of Covid in the Midwest. This region of the country is “in this wave right now,” she said.

Monitoring viruses in wastewater is the only meaningful indication of viral activity, experts say, because public health officials are no longer tracking Covid cases.

“We’ve basically abandoned other types of surveillance,” said Bill Hanage, associate director of the Center for Communicable Disease Dynamics at Harvard University, as well as Biobot’s scientific advisor.

“People are testing at home,” he said. “The only way we really have to control ongoing pandemic activity is through things like wastewater.”

Hanage compared wastewater forecasts to weather reports. “This is about as close to a forecast as you can get,” he said.

People infected with Covid shed the virus into sewer pipes about a week before feeling sick and getting tested for the virus. Every time a person flushes the toilet, it gives wastewater analysts an indication of how viruses like Covid are spreading long before there is a need for nasal swab testing.

“As long as you use toilets connected to the sewer system, we can get information about the health of communities without asking people to change their behavior. That’s why it’s so powerful,” Kirby said.

While the latest Covid sewage data is encouraging, she said people should protect themselves against a potential further increase in virus activity in the coming months.

“Hopefully with the vaccination update we won’t see a big winter surge like we have in the past,” Kirby said. “But it’s really too early to tell.”

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