Detecting Infections Early to Keep Yolo County Healthy
In September of 2020, just as the COVID-19 pandemic was ramping up for a grim fall and winter, California’s Yolo County named Dr. Aimee Sisson as its new Public Health Officer. It was a trial by fire but about a year into her tenure Yolo County joined Healthy Central Valley Together (HCVT), a project aimed at increasing access to infectious disease data using wastewater monitoring in rural and disadvantaged areas in California. HCVT uses small samples of sludge taken several times a week from wastewater treatment plants in the county.
“I don’t know if there was wastewater monitoring before COVID. If there was, I never paid any attention to it,” Dr. Sisson recalls. “When Healthy Central Valley Together came along, that’s when I really started to see the value of wastewater monitoring to see what was happening throughout the county.”
HCVT, a collaborative project between UC Davis and UC Merced, joined forces with WastewaterSCAN in December 2022, extending wastewater monitoring in the Central Valley into 2024. With data made immediately available by WastewaterSCAN, Dr. Sisson knows whether infections are rising or falling across Yolo County. Perhaps more crucially, she often knows these key metrics before those citizens even have so much as a sniffle.
Today, if someone asks her, “What’s going on with COVID right now?” Dr. Sisson will immediately pull up the WastewaterSCAN dashboard. “In fact, that’s what I’m doing this afternoon, at one o’clock, I’m doing the county’s monthly [public information officer] call. The first slide is wastewater levels.”
In addition to the WastewaterSCAN dashboard, HCVT offers Dr. Sisson and its partners across the Central Valley a weekly synthesized report on the current trends of various pathogens, including SARS-CoV-2, influenza, respiratory syncytial virus (RSV), human metapneumovirus (HMPV), norovirus, and mpox.
Sisson’s story is not unique. The data that WastewaterSCAN generates is now a go-to resource for public health officials in more than 180 communities in 36 states, for reliable, timely, and accurate infectious disease data not just for COVID-19 but more than ten other pathogens, ranging from viruses like flu and RSV, to the virus that causes hepatitis A, and the infectious fungus Candida auris. More than 40 million Americans are now within WastewaterSCAN’s purview—12 percent of the entire U.S. population.
“In the beginning, I thought WastewaterSCAN was just bonus data. Now, I feel like it’s core data. We started to rely on wastewater data,” Sisson recalls. Almost overnight, it was as if the old metrics, cases rates and PCR testing, meant nothing, she says. “Case rates are helpful, but if you’re waiting for hospitalizations to go up, you’ve missed a two-week window where people could have been preventing disease.”
And so, infectious disease data from wastewater became indispensable to Dr. Sisson. It is near real-time and comprehensive, too, testing the majority of Yolo County and other nearby Central Valley counties’ populations at once and providing relative infection rates on a daily basis. It’s also completely anonymous. No infected individual can be identified from any sample.
Today, Dr. Sisson never makes a public health recommendation or alert about COVID-19 without consulting the wastewater data—and she is watching the data while entering the flu and RSV season to look for early warning signs of disease spread.
“Wastewater levels have become the center of my communications,” Sisson says. “I check WastewaterSCAN’s dashboard three or four times a week now to see what’s happening in Yolo County. In fact, it’s actually the farthest-left tab in my browser. It never gets closed. That’s how valuable this is to me.”