Over the past few days, COVID-19 cases and the percent positivity rate in Massachusetts have begun to decline somewhat, giving residents and medical experts alike hope that the current surge might soon be coming to an end.
But top Boston doctors warn that though we are seeing a slight dip, two new omicron subvariants that are causing issues in South Africa -- BA.4 and BA.5 -- could result in another upswing here in the near future.
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Cases had been dropping in South Africa for over a month before the BA.4 and now BA.5 strains began pushing up cases. The BA.4 subvariant now accounts for about half of new infections there.
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Experts say BA.4 seems to be more transmissible than both the original omicron variant and an omicron relative known as BA.2. Scientists are still studying the new mutants, but it doesn’t appear they cause more severe disease than other versions of the virus, WHO said in a recent report.
So far, BA.4 and BA.5 haven't made major inroads in the U.S., where BA.2 and its descendant BA.2.12.1 still account for almost all cases. But BA.4 and BA.5 have been detected in wastewater in parts of the country.
Here's what Boston doctors told us about the current wave and what to expect in the coming months during NBC10 Boston's weekly "COVID Q&A" series.
COVID numbers in Massachusetts trending downward
Massachusetts health officials reported 3,084 new COVID-19 cases and 12 more deaths Wednesday. The state's seven-day average positivity rate went down to 8.33% Wednesday, compared to 8.58% on Tuesday.
Dr. Shira Doron of Tufts Medical Center said she looks at the state data every day but is reluctant to call anything a trend for a while because the number of cases reported to the state represent a vary small proportion of cases since so much testing is now happening at home.
She also said some testing centers take a few days to get the results out, "so there's always a little tail at the end that looks like it's going down."
With that said, Doron said she is now seeing a decrease that goes back to May 15, along with a corresponding decline in Boston's wastewater COVID data.
"So it's an incremental, day-by-day decrease that seems to be real, although again I always reserve judgment until later," she said.
"It looked like we were sort of at a plateau, and now things are creeping downwards a bit -- both the average weekly numbers as well as wastewater," added Dr. Daniel Kuritzkes of Brigham and Women's Hospital. "We've also had sort of a plateau locally at Brigham in hospitalizations at least for the last week or so."
Will BA.4 and BA.5 omicron subvariants keep cases high through the summer?
"The descents have been short-lived lately when we've seen these downturns," Doron said when asked what we might expect to see next. "What we've seen with omicron is it keeps splitting into subvariants and subvariants and subvariants. And there could always be something around the corner, something we know or don't know, and we do know there is BA.4 and BA.5 around the corner that's already wreaking a little bit of havoc in South Africa. It's nothing like BA.1, but that could be around the corner, and so the descent could turn around and go back up. But for now, we do seem to be in a descent."
"As with everything else, we'll tell you for sure once it's done," Kuritzkes noted. "I don't think we can predict right now if we're really at the end of the omicron surge or if we're just transitioning to a difference phase of the omicron surge."
Could Memorial Day weekend fuel COVID spread?
Health officials in Boston are urging caution during the Memorial Day Weekend as COVID-19 rates remain high. Community positivity in Boston is at 11%, local testing data shows. But will the long holiday weekend actually spur a surge in cases as some other holidays have in the past?
"It's hard to say for sure," Kuritzkes said. "On the one hand, likely a lot of people will be gathering, and we continue to have a lot of graduation events. But a lot of that activity is outdoors. It's different from Thanksgiving or the winter holidays. But it's just really hard to know. That's counterbalanced by the fact that very few people are now masking, especially when traveling. That could lead to some cases following the holiday weekend that's coming up."
"I think it will be very interesting," Doron added. "If we do see a descent through Memorial Day Weekend and no new variants or subvariants, it will be a good lesson to see what impact a holiday does or doesn't have when you're in a clear path or direction."
"So much of what we've seen before around holidays has been muddied by the concurrent arrival of new variants, so it's hard to tease out," she said. "There was a lot of emphasis around Fourth of July last year, but that's when delta came to town. Yes, there was a Fourth of July related Provincetown outbreak, but we would've seen a delta wave anyway, with slightly different timing. We found out about omicron on Thanksgiving Day, and that wave had a certain curve through Thanksgiving and Christmas. But it had that shape curve in countries that didn't celebrate Christmas."
"It's really going to be interesting when we look back into time, how much variants came into play, how much the mitigation strategies mattered and how much holidays and events mattered in the grand scheme of the big picture."
