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Coronavirus levels in Boston-area waste water have surged to second-highest point since pandemic began

The MWRA Deer Island waste water treatment plant.David L. Ryan/Globe Staff

Levels of coronavirus in Boston-area waste water have surged in recent weeks, reaching their highest level since the ferocious Omicron surge in the winter of 2021-2022, data from the Massachusetts Water Resources Authority show.

On New Year’s Day, the seven-day average of coronavirus RNA copies per milliliter of waste water reached 2,743 copies/mL in samples taken from the northern system — which includes parts of Boston and communities north of the city — and 2,583 copies/mL in samples from the southern system, which includes southern portions of the city and communities to the south.

Those levels are about 10 times higher than early November, and higher than any point since January 2022. Still, it’s important to note that in terms of waste water levels, the current surge is a small fraction of the Omicron surge two years ago. At that time, levels soared past 11,000 copies/mL in samples before quickly dropping back down.

As home testing has become the norm, waste water readings are an increasingly important way to track the amount of COVID-19 circulating in the community. Waste water testing captures traces of the virus regardless of whether a person was symptomatic or tested for the disease. During past surges, waste water spikes coincided with increases in cases and hospitalizations reported by the state, offering something of an early warning system.


Doctors told the Globe last week that they are indeed seeing more patients with COVID in emergency rooms, and that fewer people are up to date on COVID vaccines. Data from the Massachusetts Public Health Commission shows that COVID-19 is currently responsible for about 6 percent of statewide hospital admissions, up from 2 percent in early November.

Experts told the Globe that staying up to date on vaccines, wearing masks more frequently, and minimizing large indoor gatherings remain good precautions against contracting COVID-19. In addition, it’s a good idea to take a rapid test if you’ve been exposed to the virus, even if you don’t have any symptoms.


Christina Prignano can be reached at christina.prignano@globe.com. Follow her @cprignano.