Data suggests Covid cases in the US have peaked just weeks after the recent surge in infections.
Scientists tracking the spread of the virus through nationwide wastewater testing say the number of samples coming back positive has fallen 5 percent in the past week.
Dr. Cristin Young, an epidemiologist involved in the wastewater surveillance project, said: “We’re keeping our fingers crossed that the wave will plateau and possibly decline.”
If true, it would mark the end of a months-long surge in infection numbers sparked by two highly infectious new variants, Eris, or EG.5, and Pirola, or BA.2.86.
The sharp increase – which never resulted in a large increase in deaths or intensive care unit admissions – unsettled many hospitals, schools and businesses and renewed calls for masks.
Americans wear face masks while waiting in line to vote in the 2020 presidential election. Some colleges and companies are reintroducing mask requirements as Covid cases rise in the US
Scientists tracking the spread of the virus through nationwide wastewater testing say the number of samples coming back positive has fallen by 5 percent in the past week (see figure).
The decline was due to a decline in positive samples in mid-Atlantic states such as Virginia and Maryland. Collection sites in the Midwest and Northeast, on the other hand, are seeing a steady increase in Covid spread
Dr. Young and his team at Biobot Analytics are using wastewater from 257 sites across the country to track the spread of the virus, a technique pioneered during the pandemic.
Their findings show that in the week ending September 13, the number of daily new Covid cases was estimated to be around 60,000, a decline of around 5 per cent in a week.
The decline was due to a decline in positive samples in mid-Atlantic states such as Virginia and Maryland.
Collection sites in the Midwest and Northeast, on the other hand, are seeing a steady increase in Covid spread.
Biobot’s findings are supported by surveillance in North Carolina, said Jessica Schlueter, an associate professor in the department of bioinformatics and genomics at the University of North Carolina Charlotte.
She is responsible for wastewater testing at a dozen sites in her state.
The increase in Covid wastewater samples over the past six months “seems to be peaking and gradually tapering off,” she said, which could mean a decline in some cases.
Official data shows the rate of increase in Covid hospitalizations has also slowed, after rising 7.7 percent in the latest week for which data is available – marking the slowest increase since early July, when hospitalizations rose were at a record low.
Recent data shows there were 20,538 Covid admissions to US hospitals in the week ending September 9th.
There are also signs that the number of Covid deaths is gradually decreasing.
A total of 844 were recorded in the week ending August 19, the latest available. Data for the following week is incomplete, but currently suggests there were 860 deaths related to the virus in that period – an increase of 1.8 percent.
But not everyone is so optimistic.
Dr. Amy Kirby, director of the CDC’s wastewater surveillance program, said NBC News: “We’ve seen enough data over the years to know that around the time school starts, we’ll start to see increases.”
These are expected to “plateau and then fall again” before rising again in the winter, she warned.
Wastewater surveillance has “proven to be beneficial as a robust, highly adaptable platform for monitoring SARS-CoV-2 transmission at the community level,” a CDC report said last week.
According to the latest CDC data, weekly Covid hospitalizations are increasing
Deaths are starting to fall again, but rising from near historic lows
With testing for Covid now largely eliminated, wastewater surveillance is one of the only ways officials can track the spread of the virus in the US.
In a pilot study during last year’s flu and RSV seasons, concentrations of RSV and flu in wastewater samples from three large cities in Wisconsin were collected and compared to the number of emergency room visits related to the viruses in the region.
Not everyone tests for flu and RSV, so wastewater could be an important early warning sign.
Anyone infected with a virus sheds tiny fragments of their DNA in their feces.
Higher concentrations in wastewater were associated with more emergency room visits for flu and RSV.
Higher levels of the virus in wastewater often preceded emergency room visits and suggested a surge was imminent, the CDC said.
This could be used as an effective warning system for emergency department medical staff of an impending outbreak in the region.
“With updated vaccinations, hopefully we will not see as large a winter surge as we have seen in the past,” Dr. Kirby. “But it’s really too early to tell.”
