Newer coronavirus subvariants ticking up in California amid concerns of winter wave
LOS ANGELES — Amid concerns about a potential winter COVID-19 wave, cases linked to newer coronavirus subvariants are starting to creep up in California as officials in both Los Angeles County and the San Francisco Bay Area warn that a lengthy decline in new infections appears to be stalling.
Whether this trend in coronavirus cases can be blamed on the rise of the newer strains is unclear — especially since the omicron subvariant BA.5 remains the dominant version nationwide, as has been the case for months.
But officials have long warned that any new subvariant could imperil the progress against COVID-19, either by being inherently more infectious or better able to evade protection from vaccinations or previous infections.
The latest generation of alphanumerically designated omicron subvariants may have such an advantage, even over the hyper-infectious BA.5.
BA.5 “appears to be gradually accounting for fewer sequenced specimens, indicating that other variants could become more dominant in the future,” according to Los Angeles County Public Health Director Barbara Ferrer.
The erosion of BA.5’s dominance has been slow but steady. Such changes “could indicate the beginning of a growth advantage by some of the other strains,” Ferrer said Thursday during a weekly briefing.
According to the latest data from the U.S. Centers for Disease Control and Prevention, BA.5 accounts for an estimated 62% of all new coronavirus cases nationwide. However, that share has fallen markedly from mid-August, when it was thought to be behind more than 86% of cases.
In the southwestern U.S., which includes California, Arizona, Nevada, Hawaii and the U.S. Pacific territories, BA.5 remains more common, accounting for an estimated 72% of all new cases during the latest analysis period.
A few other omicron subvariants also have risen in prominence. BQ.1.1, which some officials have pointed to as a potentially problematic strain, went from an estimated 0.2% of cases nationwide in mid-September to 7.2% this month. During that same time, BQ.1 has swelled its estimated share from 0.5% to 9.4%, while BF.7 — also known as BA.5.2.1.7 — has increased from 1.9% to 6.7%.
In L.A. County, data from the week ending Oct. 1 also point to a decline in BA.5’s dominance and new subvariants making up an increasing share of cases.
But while BQ.1 and BQ.1.1, both descendants of BA.5, are gaining ground nationwide, only a handful of such cases have been documented in L.A. County. Seven have been attributed to BQ.1 and three to BQ.1.1.
Another omicron subvariant, BA.2.75.2, represents only 0.2% of cases per week in L.A. County, a rate that has been stable for three weeks. L.A. County also has not reported any cases of the XBB subvariant that has been spreading in Singapore, according to Ferrer.
Some researchers in China have found evidence that XBB “can evade antibody protections developed after BA.5 infection. We don’t yet know the full implications of this,” Ferrer said.
“Some of these mutations make it easier to evade prior immunity, meaning that many of us can be reinfected even if we were previously infected with a strain of omicron earlier this year,” she added. “And while there’s no immediate risk given the relatively low numbers of recently sequenced specimens of these new sublineages in L.A. County, we do need to be vigilant.”
While newer strains have some mutations that could provide a growth advantage, it’s unclear whether any will cause more severe symptoms than their predecessors.
And many officials and experts remain generally optimistic that available vaccines — particularly the recent released bivalent boosters — should continue to provide strong protection against the latest round of subvariants.
“We understand that there may be COVID fatigue, but we cannot let our guard down,” the California Department of Public Health wrote in a recent statement to the Los Angeles Times. “Our statewide COVID-19 vaccination campaign is still working with community partners across the state to emphasize the importance of staying up-to-date on their COVID-19 vaccines and boosters.”
The updated boosters are designed to target the original version of the coronavirus — incorporating the same formula as the vaccines available since late 2020 — and the BA.4 and BA.5 omicron subvariants. Many of the newer strains are descendants of those subvariants.
“Do I worry about the alphabet soup of new variants of concern, today’s biggies: BQ.1 & XBB? Sure, but there’s nothing we can do about them other than watch their prevalence; get boosted — even if they’re partly immune evasive, you’ll be better protected with the boost than not,” Dr. Robert Wachter, chair of UC San Francisco’s Department of Medicine, wrote on Twitter Wednesday.
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