When will this COVID surge end? Scientists search your sewage for clues

As the saying goes, never let a crisis go to waste.

And with COVID-19, a growing body of researchers and public health experts are taking that advice literally.

Scientists are increasingly using raw sewage as a tool to help determine how infections are trending in hundreds of communities across the country. By taking regular samples from wastewater treatment plants and scanning feces for the virus, they’re able to tell where infections are trending upward or downward, and in many cases, how the amount compares to prior waves of the virus.

The use of the technology made waves this week, when researchers used it to note that it appears the latest COVID-19 surge, fueled by the omicron variant, may be on the decline in Boston. Experts told USA TODAY that while the data isn’t a certainty, it very well could be one of the first indicators the nation may have hit the omicron high-water mark.

“Data has shown a pretty steep decrease, which is extremely encouraging,” said Newsha Ghaeli, president of BioBot Analytics, a private analytics company performing the testing in Boston. “And which might suggest we are actually past omicron’s peak.”

Experts say early detection of trends is one of the key benefits that wastewater testing can provide.

Marlene Wolfe, an assistant professor of environmental health at Emory University in Atlanta, is part of the Sewer Coronavirus Alert Network, a team of scientists that evaluates sewage treatment plants in California communities. They can collect, analyze, and publish data in about 24 hours, delivering nearly real-time information on how COVID-19 is trending. That’s significantly faster than analyzing positive tests from swabs, which can take a week or more in some areas.

“People are always going to the bathroom,” Wolfe said. “It’s really reliable.”

Wastewater testing is also providing some advantages as omicron surges. There are indications the variant may trigger negative and positive test results at different points after infection than earlier iterations. Also, many people are using home-testing kits and don't always report their results. And statistical evidence suggests there are vastly more people who have COVID-19 than are showing up in the system.

But experts say, because wastewater testing doesn’t require any individual testing, it gives officials an important second data set to evaluate trends.

“Wastewater’s huge value is in that it solves for most of these issues in terms of informing public health and communities about outbreaks and surges,” Wolfe said.

Ghaeli qualified the recent data indicating a downtick in omicron. She said the company will want to see additional data to ensure the decrease is a lasting trend. There are also questions of what comes next: Will omicron and COVID-19 rates fall as precipitously as they rose in early December? Or will they level off? And what would that mean for public health?

Other researchers pointed out general limitations with the technology: Is there a chance a significant number of people leave a community, such as those fleeing a city as a COVID-19 wave descends, which could impact the numbers? Or could shifting amounts of viral loads – how much coronavirus the body is actually excreting on an individual basis – throw off the numbers?

And despite the possible downturn in Boston, there are few indications that most cities across the country have reached their peak. Ghaeli said BioBot monitors more than 200 wastewater treatment plants nationwide, with data trends posted on the company’s website. It’s “too early to tell” whether there are downturns anywhere else, she said.

Wolfe echoed that, saying that testing in about a dozen California cities, the largest of which are Sacramento and San Jose, shows a few cities with possible downward trends but nothing concrete. Other cities are on the rise, and it will take more time or data to determine where peaks have occurred.

In addition, Boston was among the first cities in the U.S. to get hit with the omicron wave and has a fairly high vaccination rate. Cities with lower vaccination rates that saw a later onset of omicron cases are likely still working toward their peak, and experts advise residents to remain vigilant.

“It’s a proceed-with-caution situation,” Ghaeli said.

Longer term, the wastewater industry expects increased use of the technology to track COVID-19 rates, and even other viruses and health conditions.

Prior to the pandemic, the use of such technology was relatively niche, said Emily Remmel, director of regulatory affairs for the National Association of Clean Water Agencies, which represents wastewater utilities across the country. With COVID-19, its use picked up, but there were many limitations. Data turnaround took a while, costs were high, and funding was low.

But the system has come a long way, Remmel said. The U.S. Department of Health and Human Services has begun to issue grants to cover the costs for utilities to collect and ship the samples and for companies like BioBot to test samples each week. Numerous universities and research institutions are partnering with sewer utilities, and even individual cities or health departments have taken it upon themselves to implement the technology.

Palm Springs, California, is one. Principal engineer Donn Uyeno said the city began wastewater testing for COVID-19 in May 2020. At the time, traditional testing data was only available on the county level, and officials wanted more granular detail about how their city of 48,000 was faring.

Information from the sewage analysis helped city leaders decide when to implement measures like mask-wearing and provide at-home testing kits to residents. It also helped the city communicate with the public; local news outlets rely on the data to analyze trends, and the local health department also finds it useful, Uyeno said.

“They find value in the extra data,” Uyeno said, adding it also gave the city about a one-week’s heads up on the arrival of omicron.

Remmel said utilities nationwide are more widely finding the technique valuable and embrace the opportunity to help the public in a new way.

“Our members are really excited,” Remmel said.

Scientists are also enthusiastic about what the future could hold. Over the long term, and particularly if COVID-19 reaches endemic status, sewage testing could be an easy way to detect early resurgent spikes in the virus. The technology can also be applied to traditional illnesses like the flu.

“If we have a system of regular wastewater monitoring, there doesn’t need to be a significant ramping up of infrastructure in order to track these outbreaks,” Wolfe said.

But funding remains a key hurdle. Palm Springs, which currently samples twice a week, pays about $400 a test, and Uyeno said the cost for other providers stretched into the thousands of dollars. As the delta variant wave declined, the city prepared to stop wastewater testing because of costs – until omicron arrived. Uyeno predicts that as COVID-19 recedes again, it will be difficult to continue justifying the costs to taxpayers.

Ghaeli hopes that wastewater testing will ultimately prove valuable enough for governments to continue funding.

“Our vision is that wastewater epidemiology becomes a permanent infrastructure layer on top of our sewer systems,” Ghaeli said. “(President Joe) Biden's pandemic preparedness proposal in September explicitly mentions a national wastewater monitoring infrastructure, so we're hopeful this becomes a reality.”

This article originally appeared on USA TODAY: Scientists look to sewage to track COVID trends and omicron surge