Pair of subvariants is gaining on BA.5
LOS ANGELES — The rise of new coronavirus subvariants is continuing to erode the grip the omicron strain BA.5 has held for months, worrying health officials that a winter resurgence of COVID-19 may be ahead.
Eating into BA.5’s longrunning dominance are a pair of its own descendants: BQ.1 and BQ.1.1. Like BA.5, the two are subvariants of the original omicron coronavirus strain that walloped the world last fall and winter.
According to data from the U.S. Centers for Disease Control and Prevention, BA.5 has long accounted for the vast majority of new coronavirus cases nationwide. That these two other strains are increasing in their respective share of cases, however, could indicate they enjoy an additional growth advantage.
But what that ultimately means for this fall and winter — a period when many health experts have
already predicted some degree of COVID-19 resurgence — remains to be seen.
Los Angeles County Public Health Director Barbara Ferrer noted recently that “emerging variants and subvariants of the virus have played a large role in driving past surges.”
“We ought to prepare for the possibility of another winter surge. We want to be realistic because every COVID surge brings additional risk,” she said. “However, we’re also optimistic because we have powerful tools, including therapeutics and the new bivalent boosters, that can blunt the impact.”
At this point, BA.5 remains the most common version of the coronavirus in circulation in the U.S. — making up an estimated 49.6 percent of new cases over the weeklong period ending Saturday, CDC data show.
As recently as a month ago, federal health officials estimated it was the culprit behind nearly 82 percent of new cases.
During that same time, BQ.1 has increased its estimated share from 1.2 percent to 14 percent, CDC data show. BQ.1.1 has swelled from an estimated 0.5 percent to 13.1 percent.
“While there are no data on severity or immune escape from studies in humans, BQ.1 (and its sublineages are) showing a significant growth advantage over other circulating omicron sublineages in many settings, including Europe and the U.S., and therefore warrant close monitoring,” according to a statement Thursday from the World Health Organization’s Technical Advisory Group on SARS-CoV-2 Virus Evolution.
“It is likely,” the statement continued, “that these additional mutations have conferred an immune escape advantage over other circulating omicron sublineages, and therefore a higher reinfection risk is a possibility that needs further investigation.”
There are no epidemiological data currently suggesting that BQ.1 or its descendants are associated with increased disease severity or that they will significantly diminish vaccine protection against serious illness, according to the statement.
Even if BQ.1 or BQ.1.1 don’t make people sicker, that’s not to say their rise is riskless. As has been seen throughout the pandemic, higher numbers of infections threaten to put additional stress on the health care system.
‘Challenges ahead’
Coronavirus-positive patients, whether admitted for COVID-19 illness or with an incidental infection, require particular attention and resources to keep them from spreading the virus to others. Greater community transmission also can sicken health care workers, causing staffing interruptions and even shortages.
The circulation of other respiratory illnesses — namely influenza and respiratory syncytial virus, or RSV — also could compound any challenges presented by a coronavirus rebound. Both RSV and the flu are much more active now than typical for this time of year, a development some worry could foreshadow particularly severe seasons.
“We know that winter is a time when viruses like COVID spread more easily,” Dr. Ashish Jha, the White House COVID-19 response coordinator, said last week. “We’re also seeing a rise of other seasonal viruses like flu and RSV. And we know that COVID is still evolving. We’re seeing new subvariants. We’re seeing an increase in cases and hospitalizations in Europe.”
But while “there are some challenges ahead,” Jha said, “the great news here is that, unlike past winters, we are in control.”
“We have the tools we need to ensure folks have a safe and healthy holiday season,” he said. “And the single most important tool is the updated COVID-19 vaccine.”
Bolstering boosters
Because vaccine protection wanes over time, many could be at higher risk, depending on how long it’s been since they were last inoculated.
As of mid-October, the California Department of Public Health said about 21.9 million people — roughly 78 percent of all vaccinated recipients — were at least six months removed from their last dose.
Uptake of the updated bivalent boosters, designed to protect not only against the original coronavirus strain but also the omicron subvariants BA.5 and BA.4, also has been slow.
Nationwide, bivalent coverage among eligible recipients is 7.3 percent, according to the CDC.
Included in that percentage is President Joe Biden, who received his shot on camera last week to promote the updated vaccine.
“It’s incredibly effective, but the truth is not enough people are getting it,” he said. “We’ve got to change that so we can all have a safe and healthy holiday season.”
In terms of booster coverage, “we’re nowhere near where we need to be to actually enter into the colder months, the holidays, with that sort of additional layer of community protection,” Ferrer said.
“We’re so lucky to live in this country where we have ample access to one of the best protections against serious consequences of either influenza or COVID, which are making sure that we’re getting our vaccine,” she said. “So we’d like to make sure everyone understands we’re not helpless here. And we’re particularly not helpless on trying to really dampen the impact that a lot of transmission can have on our health care system.”
The U.S. averaged roughly 400 COVID-19 deaths a day in October, higher than the springtime lull of about 300 daily deaths.
“We still have hundreds of people dying each day from COVID in this country — hundreds. That number is likely to rise this winter,” Biden said. “But this year is different from the past. This year, nearly every death is preventable.”