Depressed by all the official statistics showing Omicron surging out of control? A more precise measure — drawn from New Haven’s wastewater — suggests the Covid-19 variant may have already peaked and is actually declining.
Yale engineers have been analyzing primary sludge (wastewater solid that’s separated by settling to the bottom) at New Haven’s sewage treatment facility since the March 2020 outbreak of the Covid-19 pandemic. They’ve analyzed the concentration of virus strands in fecal samples to get an advance look at the prevalence of Covid cases before symptoms manifest. The data is considered more accurate than official statistics because the latter are based on results from tests that people have chosen to take, rather than from everyone’s waste. The trends captured in this analysis generally show up in subsequent days or weeks in official case counts.
The latest wastewater analysis, released Thursday based on samples drawn Sunday, shows a concentration of 95,653 Covid copies per milliliter, according to engineering Professor Jordan Peccia, who leads the Yale team.
That’s a dramatic drop from the peak concentration collected just four days earlier, on Jan. 5, when the concentration was 227,095.
That left Peccia “cautiously optimistic” that New Haven’s Omicron outbreak has “started to turn.”
“The wastewater surveillance serves as a good source to assess disease within the city,” said New Haven Health Director Maritza Bond, whose team keeps a close eye on the engineers’ data. Bond shared in the cautious optimism that the local outbreak has passed its peak.
The results mirror those from wastewater samples in Boston, which showed a “sharp decline” in Covid wastewater levels. While reported Omicron cases and Covid-connected hospitalizations are surging nationally, the Northeast, which was hit earliest by the Omicron wave, has started to see signs of a peak and decline.
Similarly, in New Haven, schools, hospitals, and the police and fire departments have reported Covid-related absences dropping dramatically from a week ago.
The latest data also shows that the Omicron variant — which spreads far more rapidly than its predecessors, but also reportedly causes milder symptoms, especially among the vaccinated — now accounts for close to 100 percent of all local Covid cases.
The Omicron wave is still causing havoc: The governor’s office reported Thursday afternoon that while the official test-positivity rate remains above 20 percent in the state (20.27 percent, to be precise). But the number of Covid-positive hospitalized patients dropped by 22 since Wednesday.
A useful article, which could be even more useful if it discussed the correlation between sewage concentrations and reported cases/hospitalizations/deaths and the lag between concentration and these variables. (The short take is really high and a couple of weeks.) For my fellow wonks, published research has found an R-squared of more than .92 between concentrations and subsequent cases. This suggests (although does not guarantee) that cases here will start declining sharply in a week or so. https://www.frontiersin.org/articles/10.3389/fviro.2021.776998/full