But do residents really need to be concerned about it?
In a new weekly series, "COVID Q&A," NBC10 Boston asked three top Boston doctors on Tuesday for their thoughts on the delta plus variant.
Here's what they had to say:
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So what is the delta plus variant, exactly?
Known as AY.4.2, the so-called "delta plus" variant is believed to be even more contagious than the highly transmissable delta variant. One expert said it could be 10% more contagious than delta.
"This is basically a subvariant of the delta virus," Boston Medical Center's Dr. Davidson Hamer said. "It has two additional mutations in the spiked protein. I think there may be a few cases in the U.S. It's up to like 6 or 7% of sequences in the U.K. There's been speculation that the rising cases there may be associated with this. I think the rising cases there have more to do with opening up the economy, schools and so forth, and reducing some of the restrictions in place."
"There's speculation, but I'm not sure there's really good data yet, that this might be a little more transmissable -- maybe up to 10% more transmissable than delta itself, which is something," he added. "Delta was definitely much more transmissable than alpha. I think we need better quality data to understand it. And we'll see over time, as we continue sequencing, is this going to displace the current delta? If it's more fit and better able to be transmitted, then it will."
Is this a big deal, or will we forget about it in a month?
"We could go either way on that," Dr. Shira Doron of Tufts Medical Center said. "We watch them and sometimes they turn into something and sometimes they just don't."
U.K. government health officials have said it's too early to tell whether the mutation poses a greater risk to public health than the delta variant, which itself is significantly more infectious than the original COVID-19 strain.
"I think it's early days still," Dr. Daniel Kuritzkes of Brigham and Women's Hospital said. "Although we have seen an uptick in the U.K. of delta plus cases, at this stage it's very hard to know is that because the variant is more transmissable or is there a founder effect where the person who happens to have introduced this infected a whole bunch of people because of their circumstances and those people all went on and infected other people. Is this by chance the virus got transmitted? It can be very challenging to sort out founder effects from the true effects of transmission fitness. So a lot more work needs to be done to sort that out. We'll see over time."
"It hasn't been labeled as a varient of interest or variant of concern, so at this point it's really something that health authorities are keeping their eye on," Doron added. "I wouldn't hit the panic button yet."
How concerned should we be?
"I'm not concerned at present," Kuritzkes said. "I don't think there are data yet to suggest this variant is more likely to escape from the vaccine and neutralizing antibody control. I don't think it's so much of a quantum leap as delta was or alpha. And it doesn't have as much resistance as beta and gamma had."
"I would say ask us that question again in two weeks, four weeks. Maybe we'll be better situated," Hamer added. "A couple weeks ago we were talking about mu. I haven't heard anything about mu recently."