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Coronavirus levels in waste water remain elevated in Eastern Mass. as BA.5 uncertainty persists

Getting vaccinated and boosted is still key. Governor Charlie Baker receiving his second booster in April.Jessica Rinaldi/Globe Staff

The levels of coronavirus detected in Eastern Massachusetts waste water remained stubbornly elevated last week, below a recent peak in mid-May but still cruising above the reassuring lows reached in March.

Officials say waste water virus data from the Massachusetts Water Resources Authority 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 has become a key indicator of the virus’s prevalence.

The numbers are refusing to drop as experts worry that the arrival of new subvariants, particularly BA.5, could push up cases and, after that, hospitalizations and deaths. As of last week, the Broad Institute of MIT and Harvard estimated that 60 percent of Massachusetts COVID-19 cases were caused by BA.5 and 20 percent by another subvariant, BA.4, as they elbowed out previous subvariants.

Massachusetts COVID-19 hospitalizations have edged up slightly in the past three weeks, according to data posted Friday by the state Department of Public Health.


Dr. Ashish Jha, the White House COVID-19 response coordinator, said Saturday on Twitter that the country is at “a new inflection point” where it’s possible a new rise in infections followed by serious illness is ahead.

“Do we know exactly how BA.5 will play out in the US in the upcoming weeks to months? We don’t. No one does,” he said.

He noted that South Africa had a BA.5 surge but deaths “thankfully remained low,” while Portugal had “a sizeable wave of infections followed by a sizeable wave of serious illness and death. ... We don’t know which path the US will take — or whether different parts of the US will take different paths.”

Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, warned in a podcast Friday, “It is certainly not a time to let our guard down. The coming weeks will be very telling.”


He noted that the Fourth of July weekend had just passed and said, “We could have the perfect storm here with the transmission levels high, large numbers of people traveling, shifting attitudes about the pandemic, and a new dominant strain that has been shown to increase hospitalizations levels in several countries across the globe. We all need to keep our eye on things in the US for the coming weeks.”

Andrew Lover, an assistant professor of epidemiology in the School of Public Health and Health Sciences at UMass Amherst, said, “Unfortunately, it’s too soon to tell if we’re out of the woods yet. It may well take another week or two at least for any obvious upticks in hospitalizations, but these are occurring now in NYC, which tends to be running a bit ahead of us.”

“BA.5 has been having major impacts in many other countries, including France, Germany, and especially Israel, which is seeing increased hospitalizations and mortality. We have to assume we’ll see similar trends, especially as boosting uptake has stalled,” Lover said Monday in an e-mail.

The latest waste water data posted by the MWRA covered tests up to Thursday.

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 sections of its system. The testing determines the number of SARS-CoV-2 RNA copies per milliliter of waste water.


The northern MWRA section saw six days of gradual increases, bringing the seven-day average to 728 copies/mL on Thursday. The number had been as high as 1,273 on May 17 during the spring bump in infections. But it had dropped as low as around 100 in March.

In the southern section, the numbers wobbled up and down over the same period, ending with a seven-day average of 709 copies/mL. The number had gone as high as 1,332 on May 17. In March, it had plummeted to the low 90s.

In a different indicator of the status of the pandemic, the US Centers for Disease Control and Prevention said Friday that six Massachusetts counties — Suffolk, Middlesex, Norfolk, Plymouth, Barnstable, and Nantucket — now have medium community levels of COVID-19, and one county, Dukes, had high levels. The rest of the state’s 14 counties had low levels.

The numbers suggested the state was seeing more COVID-19. On June 23, all the state’s counties had been seeing low levels, except for Dukes, which was at medium.

The CDC calculates community COVID-19 levels each week by reviewing the number of hospital beds being used, hospital admissions, and new COVID-19 cases in an area.

The CDC recommends an increasing number of precautions, depending on how high the COVID-19 community level is, beginning with basics such as getting vaccinated and staying up to date on boosters, improving ventilation, and getting tested if you’ve been exposed to COVID-19 or have virus symptoms. If community levels are high, the CDC recommends everyone mask in indoor public spaces.


Martin Finucane can be reached at