PBS News Hour

John Yang

As the new dominant COVID variant called BQ1 emerges, scientists are looking beyond traditional methods to track its spread. The newest tool in their arsenal, wastewater. Special correspondent Cat Wise traveled to California, one of the first states to test wastewater for COVID. Cat Wise,

PBS Correspondent

Every day more than 100 million gallons of wastewater flows into this treatment facility in Santa Clara County, California. Its the largest in the San Francisco Bay area, serving more than 1 million residents in Silicon Valley. The sewage spewing out from these tanks is something most people want to avoid. Alexandria Boehm, Environmental and Civil Engineering Professor,

Stanford University

Extract the RNA from the wastewater.

Cat Wise

By Stanford University Environmental and Civil Engineering Professor Alexandria Boehm sees a public health goldmine.

Alexandria Boehm

Can we look at all the samples -

Cat Wise

Samples?

Alexandria Boehm

-- together.

Cat Wise

In March of 2020, just weeks after one of the first coronavirus cases in the country was confirmed here in Santa Clara County, Boehm and her colleagues began testing wastewater samples.

Alexandria Boehm

We found that we could detect SARS-CoV-2 RNA in wastewater, and then we found that we could measure its concentration and see how it could change overtime and how that matched with data from reported cases. I was running with my cell phone, and I got in the first set of results, and I could see right then and there that the changes in concentration were similar to what was happening with the cases. And I was like, oh my gosh, I cant believe this is going to work.

Cat Wise

Using wastewater to monitor viruses is not new. For decades scientists around the world have used wastewater to track polio outbreaks. But it had never been used to track a respiratory disease. People infected with COVID can shed their virus in their waste days or weeks before they may have symptoms, which Boehm says can provide an early warning for public health officials.

Alexandria Boehm

Wastewater surveillance is just - it could be like a complete revolution in the way that we track infectious disease in communities. And the uptake of this, like, technology is really unprecedented. Weve gone from zero to 100 in like two years.

Cat Wise

In November of 2020, she and her colleagues launched a program to track COVID at eight northern California treatment plants. It has now expanded to 70 sites and is part of the CDCs own wastewater surveillance system, which generates data from more than 1,000 sites. Justin Sablaw,

San Jose-Santa Clara Wastewater Facility Operator

Make sure everything runs smoothly.

Cat Wise

At the Santa Jose-Santa Clara Wastewater Facility, operator Justin Sablaw took us to an underground area where he and his colleagues take samples of semisolid waste, known as sludge, every four hours.

Justin Sablaw

Well we usually try to get 250 milliliters a sample roughly.

Cat Wise

The samples are sent to a lab where theyre tested not only for COVID but also influenza, Respiratory Syncytial Virus or RSV, and monkeypox, known mpox in California. The results are sent to public health officials around the country, including Dr. Sara Cody, the Head of Santa Claras Public Health Department. Dr. Sara Cody,

Head of Santa Clara Public Health Department

What you really need to do is look at where are we now in the wastewater.

Cat Wise

Cody now has more than two years worth of data showing how closely COVID cases in her country correlated with virus levels in the wastewater. Then this summer Cody says fewer people were tested at clinics and hospitals, but wastewater concentrations stayed high.

Dr. Sara Cody

When I see this, I see why over time weve had growing confidence that the wastewater is the truth, and now we can certainly see that the wastewater levels are still elevated and we trust that. We know the wastewater doesnt lie.

Cat Wise

Cody says she now regularly relies on Stanfords data to make public health decisions, like recommending that residents continue to mask indoors in public places. One downside to wastewater monitoring, however, is time and money, but officials here say it only cost about $100 every time a disease is tested. That can vary elsewhere depending on location and population being tested.

Alexandria Boehm

If you take one sample of wastewater, you could get information about in San Jose about 1.5 million or even at a small plant 10,000 people. Multiply the cost of the wastewater test by the number of people, so in that sense wastewater is not cost prohibitive. It is actually really cheap and economical.

Cat Wise

Still there are concerns some communities will be left out as wastewater testing expands. The rural town of Esparto, where nearly 50 percent of residents are Latino, is now part of a program sampling treatment facilities across Californias Central Valley. Like many communities in the area, it was hit hard by the pandemic but didnt have access to wastewater testing early on to track the spread. Heather Bischel, Civil and Environmental Engineer,

UC Davis

This is something that becomes really important if we have wastewater monitoring data to make that available for the public.

Cat Wise

Heather Bischel is a Civil and Environmental Engineer at UC Davis and one of the lead researchers in the program. She says its important wastewater testing captures data for underserved communities.

Heather Bischel

What we wanted to do was help fill that data gap and really try to focus on increasing health equity by increasing access to data across all of our communities, and especially rural areas, agricultural areas, and disadvantaged communities. Dr. Aimee Sisson,

Yolo County Public Health Officer

Downgrade to our medium levels.

Cat Wise

Dr. Aimee Sisson is Yolo Countys Public Health Officer. She says wastewater surveillance can be especially helpful for tracking disease in communities that may have limited access to testing.

Dr. Aimee Sisson

Now we have this addition tool in our toolbox to be able to look at whats happening in an entire community instead of relying on the people who are able to get tested, but I cant make any individual-level decisions. I cant say, you know, it was this household, this household, that household. And so, thats the piece that we cant tease out in terms of who needs to get treatment, who needs to isolate.

Cat Wise

Back at Stanford, Boehm hopes wastewater testing will continue to expand around the country.

Alexandria Boehm

I know in California that wastewater surveillance is probably here to stay, and I hope that there is enough funding through the state government and through the federal government to really make this part of our infrastructure for health monitoring in the United States.

Cat Wise

Infrastructure, she says, that could one day help prepare us for the next pandemic. For PBS News Weekend, Im Cat Wise in San Jose, California.