One of the facets of Colgate University’s strategy to detect signs of SARS-CoV2 on campus is the broad use of wastewater testing to find any early indications of spreading coronavirus. The plan received national attention, with news outlets like CBS mentioning the effort as a stand out among many of the college reopening plans across the country.
But wastewater sampling to detect signs of a virus isn’t new. According to Associate Professor of Biology Geoff Holm, co-chair of the Colgate Taskforce for the Reopening of the Campus, the first widespread use of this wastewater sampling was more than 20 years ago in the nation’s fight against other waterborne viruses such as rotavirus and norovirus.
“Contaminated water can be the source for many viral disease outbreaks,” Holm said. “There has been a lot of effort over the past couple of decades to detect viruses in wastewater, so this is not new as we look to detect SARS-CoV2.”
Because RNA from SARS-CoV2 appears in wastewater prior to outward signs of infection in an individual, Holm said this method of testing can help discover potential outbreaks before they would normally be detected, and the early notice can give the University critical time to conduct testing on locations that become a concern. Holm said studies have shown that viral RNA shows up about a week before symptoms occur.
Seven locations across campus are designated as collection sites where biology lab technicians, in concert with a newly hired wastewater and surveillance technician, collect samples every 24 hours. The sampling system takes small amounts of wastewater every 15 minutes from the source pipes, and that collected sample is then analyzed.
“What we’re really monitoring is the relative levels of RNA in each of those sources,” Holm said. “If that trend increases, then that is cause for concern. With the help of the Facilities Department, we have a wastewater map of campus, so, if we see increasing RNA in the waste stream at one of our locations, we know which buildings it’s coming from. At this point, what we’re doing is adding additional targeted testing above our weekly surveillance testing to locations where we see continued presence of RNA in the wastewater stream.”
Because someone who has recovered from coronavirus and is no longer infectious can still shed SARS-CoV2 RNA in wastewater, Holm said low levels of viral RNA are to be expected in these tests. But, what they are really looking for is any change in numbers that would indicate an upward trend.
“We take these data very seriously,” said Associate Vice President for Campus Safety, Emergency Management, and Environmental Health and Safety Dan Gough, who leads the University’s Emergency Operations Center. “We continue to conduct random tests of 6% of our population each week, and we have some additional test capacity for targeted sampling based on the wastewater results.”
Holm said testing everyone in a building when there are low levels of RNA in wastewater isn’t always the best answer, as this type of surveillance testing is best when trends are analyzed.
“Given what’s in the waste stream, we can’t really differentiate new cases from what may be previous cases shedding RNA,” Holm said. “It’s the trend that we’re concerned about. In some cases, the reaction to just go ahead and test everyone is misguided because you’re not using the instrument in a way that is most effective.”