COVID levels in wastewater trend up, indicating current surge will continue

Detecting the virus in wastewater is more important than ever, as fewer tests get reported to the state.

Wastewater from much of eastern Massachusetts is analyzed at the sewage treatment plant on Deer Island. David L Ryan/Globe Staff

In recent weeks, Massachusetts has seen an uptick in positive COVID-19 cases. Will this trend continue? Wastewater data, a powerful tool used to predict future cases, indicates that it will. 

The levels of COVID-19 in wastewater is an important early warning sign, as the process generally picks up infections before those that have the virus can confirm it with an actual test. At this stage of the pandemic, more residents are relying on rapid at-home tests. These results are normally not reported to public health officials, further increasing the importance of wastewater data.

The levels of COVID-19 detected at the Massachusetts Water Resources Authority’s Deer Island Treatment Plant are now back to levels not seen since late January, The Boston Globe reported

“The surge we’re seeing is real and ongoing,” Andrew Lover, an assistant professor of epidemiology in the School of Public Health and Health Sciences at the University of Massachusetts Amherst, told the Globe. “Statewide we’re seeing quite a lot of virus in wastewater.”


On Thursday, the Massachusetts Department of Public Health reported 4,957 new confirmed cases of the virus. The seven-day average of confirmed cases is now 2,985.7. This number has dipped slightly since May 15, but had been steadily climbing since mid-March. 

The MWRA Deer Island plant analyzes wastewater from 43 communities, including Boston, the Globe reported. Testing identifies the number of SARS-CoV-2 RNA copies per milliliter of water. Data is split up between the southern and northern regions of the MWRA system. 

In the northern region, the seven-day average was 1,273 RNA copies/mL as of Wednesday. That number peaked on Jan. 5, with 8,644 copies. The lowest number of copies was identified on March 9, which saw 101 RNA copies/mL, the Globe reported.

In the southern region, the average was 1,332 RNA copies/mL on Wednesday. The lowest levels this year were seen on March 1, with 92 copies/mL.

Some in the state are raising the alarm, putting pressure on officials to reinstate certain pandemic response tactics that have gone by the wayside. On Wednesday, a group led by the Massachusetts Coalition for Health Equity called on Gov. Charlie Baker and state agencies like the MBTA to issue an advisory recommending people wear masks when indoors and to avoid large gatherings.


Members of the coalition, which include healthcare workers, public health advocates and community leaders, cited the fact that not as many positive tests are being reported to the state. This could heighten the importance of wastewater analysis. 

“Everything is on the rise and on the rise quite rapidly,” said Jon Levy, chair of the Department of Environmental Health at Boston University, during a virtual press conference. “But it’s only the tip of the iceberg, and we all know that there’s a lot of at-home tests being done right now (and) not all positives are being reported to the state.”

Across the country, wastewater analysis appears to be robust on the state level but faltering on the local level. In total, 92 percent of state public health agencies and only 38 percent of local agencies had monitored wastewater for the virus, according to an April report from The Rockefeller Foundation, the Pandemic Prevention Institute, and Mathematica. 

Of course, collecting this data is not easy. Just 7 percent of the local agencies that had not monitored wastewater have what they need to begin doing so, according to the report. The most significant barrier to beginning this process is a lack of internal staff, the report found. Rural agencies were more likely to report barriers for wastewater data collection than non-rural areas. 


It also appears that although public health officials agree that wastewater data is a potent tool, many agencies based their pandemic response on other factors. The agencies that monitored wastewater rated the data as the least influential among factors that informed pandemic management. 


This discussion has ended. Please join elsewhere on