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The coronavirus levels in Eastern Mass. waste water keep increasing, suggesting cases will continue rising

Waste water coming into the Deer Island treatment plant is tested for traces of the virus that causes COVID-19David L. Ryan/Globe Staff

The levels of coronavirus detected in Eastern Massachusetts waste water have continued to climb this week, suggesting the current wave of COVID-19 cases and hospitalizations could rise still higher.

Officials say waste water virus data can be an important early warning signal, detecting COVID-19 infections before people get tested and the tests are officially reported. As more people are using rapid, at-home tests, whose results are usually not reported to state public health officials, waste water testing conducted by the Massachusetts Water Resources Authority has become a key indicator of the virus’s prevalence.

The waste water levels have now rebounded to where they were in late January.


Andrew Lover, an assistant professor of epidemiology in the School of Public Health and Health Sciences at the University of Massachusetts Amherst, said in an e-mail that “statewide we’re seeing quite a lot of virus in wastewater,” noting results of testing not just by the MWRA in Suffolk County but in five other counties around the state.

The increases come as the state’s COVID-19 cases and hospitalizations have been gradually rising for weeks, and the CDC has warned that most of the state is seeing high levels of the virus. The CDC recommends that when virus levels are high, people should mask in indoor public spaces.

With both waste water and case numbers rising, “I think it’s pretty clear at this point that we are in a wave,” Matthew Fox, a professor of epidemiology and global health at the Boston University School of Public Health, said in an e-mail.

“The surge we’re seeing is real and ongoing,” said Lover.

Fox said people should not panic “because we know what to do. For anyone not vaccinated or boosted, go out and get your vaccine. For the rest of us, it’s time to consider masking again indoors, keeping in mind that this is a time-limited measure just until the wave subsides.”


Federal health officials warned Wednesday that cases are increasing nationally and could get worse over the coming months, as the wave spreads out from the Northeast and Midwest.

Worried about the rising COVID-19 metrics, a coalition of Massachusetts public health leaders, infectious disease doctors, and community organizers on Wednesday called on the Baker administration to reinstitute mask mandates in public schools and on transportation. The group also urged the state’s Department of Public Health to issue an “immediate advisory” recommending use of masks inside public spaces and for people to avoid large gatherings until the current COVID surge subsides.

Governor Charlie Baker indicated he was not planning to reinstate a broad-based mask mandate. “We believe that the best thing to do at this point is to make clear to people that vaccines work,” he said Wednesday. “There are treatments that now work as well.” He pointed out that Massachusetts still requires masks in long-term care and in other health facilities.

Experts have raised concerns that the arrival of the Omicron subvariants BA.2 and now BA.2.12.1, are breathing new life into the pandemic at a time that the public is trying to return to normal after more than two years of pandemic disruption.

Some models have offered hope that the current Massachusetts wave could crest in the coming weeks. Experts think that would happen for a variety of reasons, including the immune protection people have gotten from vaccinations and previous infections.


How much protection people have gotten from being infected during the original Omicron wave earlier this year is a key question that has yet to be answered. Dr. Ashish Jha, the White House COVID-19 response coordinator, said at a briefing Wednesday, “If it generated a lot of population immunity, then we’re going to see fewer infections into the summer, fall, and winter. If it generated only a modest amount of immunity, we’re going to see more infections.”

Early this year, the Eastern Massachusetts waste water levels dropped precipitously from their Omicron peak. They bottomed out in early March, then began rising again. The rise was interrupted by a dip last month, but the levels have now more than bounced back.

The numbers remain at much lower levels than they were when the Omicron surge hit the region during the winter. The number of confirmed reported daily COVID-19 deaths has been in the single digits for weeks, only edging back over 10 in recent days.

Waste water from 43 communities, including Boston, converges at the MWRA’s Deer Island plant on Boston Harbor for treatment before being piped miles into the ocean. The water is tested for traces of the deadly virus. The MWRA reports numbers for both the southern and northern regions of its system. The testing determines the number of SARS-CoV-2 RNA copies per milliliter of waste water.

In the northern MWRA region, the seven-day average was 1,273 RNA copies/mL as of Tuesday. That’s up from a low of 101 on March 9. The levels peaked at 8,644 on Jan. 5.


In the southern region, the seven-day average was 1,332 RNA copies/mL on Tuesday, up from a low of 92 copies/mL on March 1. But it’s a far cry from the high of 11,446 RNA copies/mL reached on Jan. 3.

Kay Lazar of the Globe staff contributed to this report. Material from prior Globe stories was used in this report.

Correction: A previous version of this story listed the incorrect day for the most recent MWRA waste water test results.

Martin Finucane can be reached at martin.finucane@globe.com. Christina Prignano can be reached at christina.prignano@globe.com. Follow her on Twitter @cprignano.