New evidence suggests that the Omicron variant may be charging across New England and the rest of the country at a breakneck pace, threatening to push legions of additional patients into hospitals already overwhelmed with patients sick from the Delta variant, the flu, and other illnesses.
Boston on Wednesday reported three new cases in young adults, who had mild symptoms. And researchers at the Broad Institute of MIT and Harvard, which does the lion’s share of COVID testing in the state, told the Globe they have reported about 15 Omicron cases to Massachusetts and federal public health agencies.
But the Baker administration has so far reported only a single Omicron infection in the state, and declined to answer questions from the Globe about cases linked to the new variant.
“Omicron is moving extraordinarily fast, faster than even the most pessimistic among us thought that it was going to move,” said Jacob Lemieux, an infectious disease specialist at Massachusetts General Hospital and co-leader of the viral variants program at the Massachusetts Consortium on Pathogen Readiness.
A new study from researchers in Hong Kong found that Omicron infects the airways to the lungs around 70 times faster than Delta or the original COVID-19 strain. That paper added weight to early on-the-ground observations from South African doctors.
Dr. Anthony Fauci, the top US infectious disease specialist, said in a briefing Wednesday that studies so far show booster shots provide strong antibody responses against Omicron. The protections are weaker with just two doses, he said. Fauci added that, as of now, there’s no need to develop a specialized vaccine just for Omicron.
“Our booster vaccine regimens work against Omicron. At this point, there is no need for a variant-specific booster,” said Fauci, who also leads the National Institute of Allergy and Infectious Diseases.
Hints of the virus’s accelerating spread in Massachusetts come from preliminary tests that are strongly suggestive but not definitive. That data, along with experiences in other countries, points to an Omicron wave coursing over the now-dominant Delta, experts said.
“The surge that is going to unfold over the holidays is likely going to be a mixed Delta-Omicron surge,” said Lemieux.
Some laboratory tests can detect a genetic change in the coronavirus that often indicates the presence of Omicron. The lab at Massachusetts General Hospital has seen sharp increases in samples with the genetic anomaly, with 19 percent of samples tested Wednesday showing signs of likely Omicron, up from 13 percent just the day before, Lemieux said. Researchers from Yale New Haven Hospital and the University of Washington this week posted data showing increasing numbers of samples with the genetic change.
But it takes seven to 10 days to complete the full genomic sequencing that would confirm the presence of Omicron. As a result, the official case counts probably represent a fraction of the current infections, Lemieux said.
“It is alarming to see how quickly this virus is spreading,” said Bronwyn MacInnis, director of pathogen genomic surveillance at the Broad Institute. “We need to continue to be vigilant about what an Omicron wave could mean for our communities.”
Among New England states, Connecticut has reported 11 Omicron cases as of last week (with an update expected Thursday). New Hampshire and Rhode Island each reported one case, while Maine and Vermont have not recorded any.
The Centers for Disease Control and Prevention estimates that Omicron accounts for 2.3 percent of COVID-19 cases in the Northeast and 3 percent nationwide, but experts said that is probably an underestimate.
“The Omicron wave is moving so fast that it has exceeded our ability to track it precisely,” Lemieux said. “What’s clear is that the Omicron wave has already started. We need to prepare to deal with that reality, now.”
That means people need to take the measures they are most tired of hearing about: getting vaccinated and getting a booster shot if eligible, wearing masks in public places, avoiding crowds, and reconsidering holiday plans.
“The virus has spread around the globe in under two weeks. It’s already present throughout the US. There’s a high likelihood that it will come to your holiday gathering,” Lemieux said.
With Delta infections already surging in Massachusetts, Governor Charlie Baker on Wednesday announced that Fenway Park would open in January to administer booster shots to eligible adults. And he urged Massachusetts residents to take advantage of the 2.1 million rapid tests his administration is distributing this week to 102 hard-hit communities.
“It’s very important for folks, if they want to protect themselves and their family members, especially their elderly or vulnerable family members, [to] get tested before you go to that event,” Baker said. “And if you test positive, take it seriously. Isolate yourself.”
Local experts have already started rethinking their holiday plans.
“I and many of my friends and colleagues are reevaluating whether some of the things that were planned make sense,” said Lemieux. “And that’s frustrating for everybody.”
Omicron is so highly transmissible that in other countries with comparable vaccination rates to the United States, cases have doubled about every four days, MacInnis said. It is now the most common variant in the London area and represents 30 percent of cases in Toronto, she said.
“That’s alarming because our hospitals are already filling up,” Lemieux said. “There may be limits on the capacity to handle the kinds of caseloads that we see from an Omicron wave superimposed on a Delta surge.”
Adding to the stress, some of the treatments for people sick with the coronavirus, such as certain monoclonal antibodies, don’t work against Omicron.
As Omicron increases across the state, it’s unclear how it will interact with the dominant Delta, MacInnis said. It may outcompete Delta, or it may just add to it.
But either way, it poses several risks. The most vulnerable people, such as the elderly and people with weakened immune systems, “will suffer the most,” she said. And with the virus spreading so much, there’s a greater risk of more mutations that will “throw a wild card into the trajectory of the pandemic.”
“It’s going to be an interesting winter, to say the least,” MacInnis said.
This story has been updated to more precisely describe the results of the Hong Kong study on Omicron.