At the outset of the COVID-19 pandemic, fear rightfully gripped the world. As others panicked, Adam Smith ruminated. The associate professor in the Sonny Astani Department of Civil and Environmental Engineering considered ways to use science to better understand the deadly virus.

Smith wondered whether wastewater surveillance — testing sewage to ascertain virus concentrations — could track COVID outbreaks, just as it had monitored polio decades earlier.

COVID is “a respiratory illness that infects the entire body,” Smith said. “If it’s in the GI tract, then it’s probably in our waste and in our wastewater. So, I really started to think about using wastewater as a valuable tool to track community infection dynamics.”

The USC Viterbi School of Engineering professor reached out to colleagues at Rice University, North Carolina State University and Howard University. In early 2020, the researchers jointly applied for and received an expedited grant from the National Science Foundation. Soon thereafter, Smith began successfully measuring coronavirus levels in sewage at the Hyperion Water Reclamation Plant in Los Angeles, documenting when coronavirus levels increased or decreased in the population.

Although pleased with the study’s results, Smith recognized its limitations. “Hyperion serves a population of 4 million. So, if you see an increase in [COVID] wastewater data there, what are you going to do with that? How do you act on it?” he asked. “There’s really nothing you can do other than maybe raise public awareness. There’s no allocating of health care resources at that point, because that’s too large of a population.”

But what if you could monitor wastewater for COVID and other viruses in a more targeted fashion — say at USC student housing? Armed with science and a passion to protect people’s lives, Smith went into action, eventually creating one of the most effective university wastewater surveillance programs in the country for the detection of COVID and other viruses.

 

Wastewater monitoring at USC

In fall 2020, Smith and his research team began a pilot program with two campus residential buildings. They installed a couple of so-called autosamplers to test fluctuating COVID levels in wastewater. Smith’s goal: “To proactively prevent viral outbreaks and maintain a safe campus environment with an early-warning system.”

As Smith had done with water testing at the Hyperion Water Plant, he and his team showed a correlation between increasing levels of the virus in sewage and COVID outbreaks. With support from the Provost’s Office, USC installed 26 surveillance systems at eight dormitories and two on-campus apartments by the end of 2021. Eventually, Smith also began testing much of university housing for the flu and norovirus, or the stomach flu.

“Our approach tests far more viruses and monitors more students than most other universities,” Smith said. “It’s very effective.”

USC’s on-campus testing regimen continues to this day. It especially works well for the coronavirus, which has an incubation period of several days, a time lag that gives health officials the opportunity to take actions to mitigate an outbreak, said Angie Ghanem-Uzqueda, an epidemiologist and clinical assistant professor at USC Student Health.

“The great thing about wastewater surveillance is that it gives us really timely results,” she said. “By having that information, we can implement measures quickly to prevent people from getting infected.”

When Smith and his team detect rising levels of COVID in a building’s wastewater, they share the results with USC Student Health and the Environmental Health & Safety Office, or EHS. If the viral concentration is severe enough, EHS or Student Health, in collaboration with USC Housing, sends an email to students letting them know they might have been exposed and encouraging them to get tested and to isolate if their results come back positive.

“This ensures people are more aware of their health and can take appropriate measures so that they don’t expose anyone else,” said Deona Willes, EHS executive director.

Additionally, when students are informed of rising levels of the flu virus in their dorms and apartments, they might decide to get a flu shot, Smith said. He added that when viral levels surge in wastewater, EHS has buildings’ common spaces and bathrooms deep-cleaned, including sinks and toilets during norovirus scares.

 

Outbreaks and vacations

Covered by green mesh and dispersed throughout campus, USC’s autosamplers have built-in pumps that connect to the sewer pipes of the dorms and student apartments under surveillance. The samplers, about the size of a cooler, are refrigerated to prevent the degradation of water samples before testing.

On Mondays and Thursdays, Smith’s team gathers wastewater, collected over a 24-hour period, from each autosampler. Through a process called electronegative filtration, researchers concentrate the viruses and then extract RNA. They later convert the RNA to DNA, which allows them to quantify COVID, flu and norovirus viral levels as minimal, low, moderate, high and very high.

“Spikes occur on campus anytime we have a break and people travel,” Smith said. “So, you typically see them at the beginning of the fall semester, after Halloween, after Thanksgiving and then at the start of the spring semester.”

The biggest COVID outbreak, he added, happened in October 2022, when coronavirus viral loads were nearly 30 times higher than just one month earlier.

Given that people no longer get tested as much for COVID, even though it continues to circulate at sometimes high levels, Smith said he thinks wastewater surveillance, both at a micro and macro level, remains a cost-effective way to keep people informed about potential outbreaks and the accompanying risks.

Smith, a foremost expert in the field, led a group of USC researchers in 2022 that for the first time discovered bacteria in L.A. wastewater that is resistant to a last-resort antibiotic. His team sampled untreated wastewater from two of L.A. County’s largest treatment plants, showing that the resistant bacteria is more rampant than previously thought, the Los Angeles Times reported.

Looking forward, Smith hopes to test for more viruses at USC. He also wants to raise awareness by creating a public dashboard, or website, that “anybody can access and that would give you a good sense of the levels of each of these infectious diseases on campus at any time.”