New COVID-19 variant increasingly showing up in wastewater samples

BA2 More Contagious Than Omicron

MEDWAY, Mass. — The rapid demise of the Omicron variant, coupled with increasing vaccination rates, gave many cities and states enough of a ‘comfort level’ to lift mask mandates and restrictions on gatherings.

But was that move premature?

Recent wastewater data suggest COVID-19 is clawing back.

In the 15-day period of February 25 - March 11, about 40 percent of the sites that make up the National Wastewater Surveillance System (NWSS) saw COVID numbers rise. Two-thirds of those sites reported COVID increases of 100 percent and higher.

One of those sites is in Hampden County, Massachusetts — the only one in the state participating in the NWSS. It saw a 15-day increase of 1000 percent or higher.

Monitoring sites in Boston, not affiliated with the NWSS, show a slight upward trend in viral shedding.

Measuring virus fragments in wastewater is especially useful because it can pick up cases that would otherwise go undocumented — such as those with asymptomatic infection, or those testing at home.

COVID’s revival is both foreseeable and frustrating.

“We see this curve dropping and we’re like, yay we’re free — and then we open and the curve increases again,” said Colleen Naughton, PhD, an assistant professor at the University of California, Merced — and developer of a Covid-19 Wastewater Dashboard.

“So we kind of know what’s going to happen. We just want it to be over.”

Naughton said it’s not just the drop in restrictions causing the wastewater numbers to go up — there’s a new form of COVID circulating, as well. It’s called BA2.

“We’re seeing it rise as a proportion in the wastewater for those that are monitoring separately for variants,” she said. “It’s a lot more transmissible even than the original strain of Omicron.”

Dr. Richard Ellison said BA2 should qualify as a new variant.

“It’s not like it’s son of Omicron or daughter of Omicron,” he said. “It really is a separate strain.

And suddenly, BA2 has taken off in the U.S. — just as it did in Europe.

“We first saw B-A-2 and there was not a real increase in cases,” Ellison said. ”But, having said that, it clearly is more contagious.”

The CDC reports BA2 now makes up about 23 percent of U.S. COVID cases — that’s up from 12 percent the week before.

Ellison said he’ll become most concerned about BA2 if hospital cases begin to rise — but the wastewater data nonetheless gives him pause.

“I think that it makes sense for all of us to be a little more cautious,” he said.

Naughton agreed.

“We should be taking it to be put on our guard,” Naughton said. “Just be a little more cautious and use the tools we’ve learned throughout the pandemic.”

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