The levels of virus in Boston-area wastewater appear to have dropped from the latest peak, according to new wastewater data from a Massachusetts Water Resources Authority tracking system, a promising sign as the region and state deal with all-time-high levels of COVID-19 cases. It's a development that makes public health experts cautiously optimistic Boston will soon be past the worst of the omicron-fueled coronavirus wave.

According to the latest data, COVID levels are averaging around 6,000 RNA copies per milliliter, which is down from a peak around 10,000 in recent weeks. That data corresponded with high levels of cases — more than 20,000 per day in the past week, according to figures from the state health department, more than double Massachusetts' previous counts.

"Hopefully it means that there's light at the end of the tunnel in the sense that we have peaked and we are coming down," said Nour Sharara, a public health scientist with Biobot Analytics, the Cambridge-based company that runs the MWRA's tracking system. "And this is similar to what happened in South Africa where we're hoping that we see something similar where by when it started falling, it fell fast."

Tufts Medical Center epidemiologist Dr. Shira Doron said Tuesday that the new figures offer a glimmer of hope that the Boston area will soon turn a corner — and quickly.

“We really try not to ever make any predictions about this virus — because it always throws us for a loop — but in this particular case, we hoped that we would follow in the footsteps of South Africa and see a steep downturn like they did,” she said. “We could have seen a peak and a slow decline, like we were seeing with delta before omicron came along, but at least the wastewater is suggesting a steep decline, and so we hope that means cases will decline steeply as well, and then hospitalizations and deaths will follow.”

Even with the signs that case counts will soon drop, Dr. Bill Hanage, an epidemiology professor at the Harvard T.H. Chan School of Public Health, says it’s important to keep mitigation efforts in place to protect vulnerable groups.

“We still have to be concerned about infections among older adults, especially those unvaccinated, which are likely to be a problem for some time. So we should not let up mitigations protecting those age groups,” Hanage wrote in an email to GBH News. “We also do not know yet whether there will be a long tail in cases, fueled by schools reopening or other changes in the sorts of contacts we make.”

Sharara cautioned that while the levels of COVID in wastewater are coming down, they're dropping from a high number, so the commonwealth isn't out of the woods yet.

A chart from March 2020 to present day with some ups and downs, a dramatic spike up starting around December 2021 and then a steep drop down.
The prevalence of COVID-19 in Boston-area sewers dropped steeply in the latest data, released Tuesday, Jan. 11.
Courtesy of Biobot

"I think this is the next thing that we're curious about to look at in wastewater is, it's coming down, is it going to plateau? Or is it really going to fall fast and hopefully bring us back to levels as low as what we had before Thanksgiving?" she said.

Sharara said that wastewater has tracked clinical case data closely since the start of the pandemic and is optimistic that a drop in cases will follow in a few days.

"Hopefully this is good news for our communities, it's also good news, hopefully, for the healthcare system," she said. "Of course, hospitalizations always lag cases by about two weeks and deaths lag cases by about three weeks, so I think that this impact will be seen in a few weeks, and as I said the levels in wastewater is still high. But it's reassuring that it's on its way down."

Massachusetts healthcare system was already taxed, Doron recalled, even when COVID-19 cases were at their lowest last June.

“Then delta came along [in the fall] and that was already really pushing us to limits,” she said. “And so we didn't have any leeway for this omicron wave, and so it is really beyond difficult — just between the extra COVID patients and then the massive amounts of staff illness. ... It is just nearly impossible to manage.”

Sharara added just because the wastewater level is down doesn't mean it can't come back up.