COVID-19 experts say Omicron is peaking in the US, citing data from poop samples

• A network of over 100 US wastewater-treatment plants is measuring COVID-19 levels in our poop.
• "The level of the virus in the wastewater is at a record high," one scientist said.

When Mariana Matus wants to know how bad the COVID-19 rates are where she lives, she looks to the poop.

"It's crazy, but I do look at the wastewater data," the CEO and cofounder of Biobot Analytics told Insider. "That's what heavily informs the level of risk I'm willing to take, personally."

It may sound gross, but it's quite a sophisticated, science-backed early-warning system for infectious-disease surveillance. It's one that the Centers for Disease Control and Prevention is trying to scale up nationwide.

Matus' company is monitoring COVID-19 rates at more than 100 waste-treatment plants around the US and keeping track of which variants are most prevalent where.

It's not a real-time warning system, but leading disease watchers across the country are using the data as a reliable snapshot of how much virus people flushed down the toilet about one week ago.

That data, in turn, can give a good indication of how much coronavirus has been spreading. And right now, the poop is telling us there is more COVID-19 than ever getting passed around and we may be reaching an all-time Omicron peak.

Why poop is a good tool for measuring COVID-19 levels

The reason wastewater is such a valuable pandemic tool is that people who have COVID-19 poop it out.

Their deposits are not infectious — but they do turn PCR tests positive, in a similar way that throat and nose swabs do.

Since at-home COVID-19 tests are not always done correctly, and the results are not often recorded, tracking poop samples on a populationwide scale is proving a much better tracking system.

To get the data, Matus' team conducts sampling at each treatment plant at least once a week, sampling nearly continuously over the course of a 24-hour period. ("We assume everybody will use the toilet at least once" during that time, she said.)

Then, they measure how much coronavirus is in the poop people have flushed over the course of a day compared with harmless viruses we excrete all the time.

"When the number of COVID-19-positive samples in sewage go up, three to seven days later, the number of reported cases go up," Mia Mattioli, a CDC environmental engineer, said in an October blog post about the process.

Right now, the poop forecast is telling us there is COVID-19 everywhere, and a lot of it.

Nationally, "the level of the virus in the wastewater is at a record high," Matus said, adding: "It's the highest it's been throughout the pandemic, which indicates it's the most disease transmission that we have seen in the pandemic so far."

Matus lives in the Boston area, which has some of the most sophisticated publicly available poop data, courtesy of Biobot, her company. (The state of Utah is another US leader in the collection of COVID-19 poop data).

Early signals that Omicron infections are starting to decline, courtesy of our poo

In recent weeks, Boston's poop has been quite COVID-rich. In it, there are some early signals that infection rates are starting to decline from the recent record high:

According to Matus, what's happening in Boston mirrors what's beginning to happen nationally.

If the trends continue, infection rates should decline sharply soon.

"I still expect another one to two weeks of very high disease activity," Matus said. "The next two weeks we should be very, very careful."

Hospitalizations lag about three weeks behind the infection trends and may not spike until February.

The poop projections back up what infectious-disease modelers from Texas to Washington are starting to project: The Omicron wave is slowing down.

"The intense part should probably be over in many places in the month of January," Christopher Murray, the lead modeler at the Institute for Health Metrics and Evaluation, said last week.

Matus sees at-home tests, coupled with our poop data, as the future of comprehensive COVID-19 disease control.

"At-home tests are really important so people can make rapid decisions about themselves, their social activities, their level of social distancing and so on," she said. "And wastewater epidemiology data allows us to understand the true level of the pandemic."

What we flush away isn't just useful for tracking coronavirus infections; poop data could also offer insight into how widely influenza circulates each year or how much opioid use there is in a community. Our feces can show us quite a lot about how healthy we are, which makes poop a rather useful public-health barometer.