ITHACA, N.Y.—While available information about current COVID-19 levels has shrunk, the rate of infection itself has continued to fluctuate, seemingly settling into a cyclical ebb and flow of rising and falling infections every few months without an end in sight.
But those still justifiably interested in the pandemic’s current trends, locally and nationally, are facing fewer avenues for information. One that has emerged, though, is from an unlikely source: wastewater, which is now being tested for COVID-19 levels at the Cayuga Heights and Ithaca wastewater treatment facilities. Cayuga Heights has been doing so since early this year, but Ithaca just started a few weeks ago.
Current testing shows a mixed bag, though some encouraging signs. Over the last two weeks in Ithaca, the “intensity” of COVID-19 in local wastewater has been trending steeply downward. In wastewater testing, “intensity” translates to the ratio of COVID-19 gene copies detected in a certain sample of fecal matter.
Cayuga Heights’ data is not as optimistic. Both areas fall into the “substantial to high” range of community transmission, the highest category for transmission that the state lists (the others are “low” and “moderate”). See both of these graphs here.
To put numbers to those two-week trends, there’s been a 15% uptick in Cayuga Heights COVID-19 RNA in wastewater sampling, while there’s been a 79% decrease in Ithaca’s. The latter number should be viewed with some skepticism, considering the volatility that can accompany such a small sample size so far — another few weeks of testing should provide a more stable trend map.
Cayuga Heights Supervisor Linda Woodard said the village was originally supplying samples to Syracuse University in 2020, but funding for that program ran out by the end of the year. In February 2022, the village restarted sending the samples to Syracuse through a new state Department of Health program.
Wastewater testing actually looks for similar material as is tested for during the more conventionally employed nose or throat testing for COVID-19. Waste is collected and analyzed, then the RNA therein is assessed for the presence of COVID-19. Certain levels of COVID-19 RNA in the waste can correspond to a certain prevalence of infection in the community whose waste is collected at the plant.
Kruppa said that the relatively small size of the Cayuga Heights testing sample made it so that the health department wasn’t publicizing the results (though they have been available through New York State since February). Cayuga Heights’ plant is listed as serving about 10,000 people, whereas Ithaca’s is listed as serving nearly 60,000. He said considering the geographic proximity, trends and levels in Cayuga Heights will likely match those founds in Ithaca’s wastewater now that it is being tested.
“We’ve worked with the state and have been able to add the Ithaca Wastewater Treatment Plant, which, being larger in size and being impacted both by residents and people commuting in for work and business, will have a better sampling for what’s going on in the county,” Kruppa said.
Sampling started in late April in Ithaca — a better-late-than-never situation.
“It’s really to give an early warning indicator of the prevalence of the disease in the community,” Kruppa said. “It’s there for places or times when you don’t have a lot of individual testing going on. For example, if things quiet down over the summer and less people are getting tested and testing becomes less readily available, then sampling the wastewater would give us an indication if disease levels were increasing in the community.”
Everybody’s waste goes to the same place (the same dump, perhaps), so it’s not like a COVID-19 case can be discovered and traced back to a singular person through wastewater testing. Pinpointing spread in an exact community also seems nearly impossible, unless the communities are specifically tested separately. Kruppa said the method is more of a way to keep tabs on community spread at a more bird’s eye view level.
“More information is always good,” he said.