Sewerage samples show virus rising again
A worrisome climb in the state’s COVID-19 sewage samples could be tied to the more contagious U.K. variant, infectious disease experts tell the Herald.
The rise is yet another reminder that Massachusetts is “not out of the woods yet” when it comes to another possible surge of cases amid the vaccine rollout.
Recent results in Massachusetts Water Resources Authority’s study to track COVID-19 in Greater Boston shows the highest amounts of viral RNA since January.
There is sometimes “noise” in the data, said Boston University’s Davidson Hamer, but the increase is rather concerning as the B.1.1.7 variant originally found in the U.K. spreads in Massachusetts, he added. The state has confirmed 51 cases of the variant.
There has been some early evidence that people infected with the variant shed more of the virus.
“If the data is true with that study and people with the B.1.1.7 strain shed the virus for longer, then it could result in more virus in the wastewater system,” said Hamer, a professor at BU’s School of Public Health and School of Medicine. “It will be helpful to see what happens in the next measurements.”
Sunday’s wastewater sample in the MWRA southern region recorded 848 viral RNA copies per milliliter.
That figure was around the average for the southern region at the end of January, as state virus cases averaged 3,000 per day. Now the state’s daily average is 1,157 cases.
Last Friday’s wastewater sample in the MWRA northern region showed 579 viral RNA copies per milliliter. That figure was also about the average for the northern region at the end of January.
“It is worrying but not altogether unexpected,” said BU epidemiology professor Matthew Fox. “We don’t know for sure why it is creeping up, but since the wastewater data has been pretty good to date and telling us about changes in cases, it could mean that we’ve reached the bottom of the reduction in cases we have been seeing and this could reflect a new increase.
“But it is too early to say that for sure and we’d want more data before we can say for sure,” he added.
With the more contagious variants here, it’s key to continue doubling down on infection prevention measures, including wearing masks and social distancing, said Todd Ellerin, director of infectious diseases at South Shore Health.
“We don’t want to take our foot off the brakes at all,” he said. “We’re not out of the woods yet as far as another surge between now and the summer.”