As COVID-19 cases continue to spike in Massachusetts, there's another troubling sign that things may continue to get worse before they get any better.
Traces of COVID-19 at the sewage plant that treats wastewater for Boston and many of its suburbs are higher right now than at any point during the pandemic, according to public data shared by the Massachusetts Water Resources Authority.
Get top local stories in Boston delivered to you every morning. Sign up for NBC Boston's News Headlines newsletter.
Dr. Ashish Jha, dean of Brown University's School of Public Health, expressed his concerns about the data over the weekend on Twitter, noting that the state's wastewater data "shows more infections in the community than we had in April."
Others have also been sounding the alarm on social media.
Biobot is testing the wastewater at the Massachusetts Water Resources Authority's Deer Island wastewater treatment plant. The company, the first in the United States to try this approach, has shown it can give an early indication of a rise in cases based just on what's in sewage.
Forty-three communities from eastern Massachusetts have their water treated at the plant, including Boston, Cambridge, Framingham and Quincy.
The data extracted from Deer Island cannot be linked to specific cities, towns or neighborhoods, but it is providing public health officials with a big-picture outlook of what is going on in the region.
Unlike coronavirus cases -- which are detected when people get tested -- COVID-19 data from sewage measures how prevalent the virus is in the community at large, including among people who don't have symptoms and don't get tested, since the virus they shed through body waste would contribute to levels found in sewage.
The wastewater spike comes amid a spike on coronavirus cases, which caused Gov. Charlie Baker to implement new restrictions effective Sunday, including a rollback to Phase 3, Step 1 of reopening, strengthened mask guidance and a reduction in gathering sizes.
Massachusetts health officials reported 3,627 new confirmed coronavirus cases Tuesday. The state Department of Public Health also announced 40 more deaths from COVID-19.
There have now been 10,833 confirmed deaths and 253,649 cases, according to the DPH. Another 243 deaths are considered probably linked to COVID-19 at this time.
The average rate of COVID-19 tests was 5.81% as of Tuesday, according to the report — an increase from Monday's 5.46%.
