Omicron BQ variants dominant in US, last antibody therapies falter
According to the latest modeling from the Centers for Disease Control and Prevention (CDC), a pair of Omicron subvariants (BQ.1 & BQ.1.1) now account for half of all SARS.CoV.2 infections in the United States, swiftly surpassing the previously dominant BA.5 variant. Related new research also indicates our current monoclonal antibody treatments may be ineffective against BQ variants.
Following several months of relative consistency, the BA.5 Omicron subvariant has been swiftly replaced in a matter of six weeks by two new subvariants. BQ.1 and BQ.1.1, descendants of BA.5, were only added to the CDC variant models in early October after being first detected in late August. According to the latest CDC modeling the pair of BQ variants now account for 50% of samples analyzed in the United States. BA.5 is rapidly diminishing from week to week, currently accounting for less than a quarter of infections.
As with most twists in the story of SARS-CoV-2 over the past three years, it's unclear what the emergence of BQ means for the future of the pandemic. Those tracking the specific mutations in the virus indicate these new subvariants are finding novel ways to slip past our pre-existing immunity. But, that doesn't necessarily lead to disastrous new waves of infection and death.
France was one of the first countries to face a major BQ wave in October. And while infections did spike for a short period of time, they quickly leveled off, without any serious increase in hospitalizations.
On top of those epidemiological observations researchers are not seeing major differences in disease severity from BQ subvariants. According to Eric Topol, founder of the Scripps Research Translational Institute, these are all really promising signs that an optimist could interpret as the world traversing the path to COVID becoming endemic.
"Under pressure from prior infections, vaccinations, boosters and combinations of these, the virus is having a harder time finding new hosts," Topol speculated recently on his blog Ground Truths. "You might think that BQ.1.1 would qualify as an acid test and so far its outcome looks far more favorable than initially projected."
Despite BQ.1 and BQ.1.1 not immediately turning into the doomsday variants some hyperbolic commentators have predicted, the story of the pandemic is far from over. BQ is not the end of the line for SARS-CoV-2 mutations. Variant trackers have already detected several extensions of the BQ lineage (BQ.1.1.2, BQ.1.1.8, BQ.1.1.10), as well as other lineages that have converged on similar mutational advantages, such as the recombinant lineage XBB, which has moved past it original form into XBB.1, XBE and XBF variants.
Some musings on SARS-CoV-2 evolution— Moritz Gerstung (@MoritzGerstung) November 17, 2022
TLDR: The share of the variant zoo increased further with BQ.1* and XBB* at the top.
But there are interesting patterns underneath which can be illustrated by one exotic lineage: CH.1.1.
It’s rare, but it rises as fast as BQ.1.1. Why? pic.twitter.com/arJBGbMgXO
On Twitter, German researcher Moritz Gerstung mused about a newly emerged exotic lineage dubbed CH.1.1. The subvariant is derived from BA.2 but independently acquired the same key mutations seen in BQ.1.1. Gerstung described the appearance of CH.1.1 as a "curious exemplar of convergent evolution" highlighting how predictable the movement of the virus is at the moment.
Although each new recent iteration of Omicron has yet to lead to a major new wave there are still plenty of concerns over the direction the virus is heading. For example, recent research has found BQ variants present significant resistance to our last few monoclonal antibody treatments.
Following the spread of early Omicron variants this year, clinicians were left with just one monoclonal antibody treatment that works: bebtelovimab. A second preventative monoclonal antibody cocktail, called Evushield, has also remained effective. Unlike bebtelovimab, which is administered as a treatment for those already sick with COVID-19, Evushield was developed to prevent infections for up to six months in those most vulnerable to illness.
A correspondence published in The Lancet Infectious Diseases has reported testing all currently clinically used antibodies against emerging Omicron subvariants. The research indicates BQ.1.1 is the first novel Omicron subvariant to show resistance against all current monoclonal antibody treatments. The advice for doctors in regions with high levels of BQ.1.1 transmission is to move quickly to antivirals such as Paxlovid in vulnerable patients instead of relying on these previously effective antibody treatments.
Jeremy Luban, from the Massachusetts Consortium on Pathogen Readiness, said the loss of these two antibody treatments will be felt most by those with weakened immune systems. And the lack of any clinical antibody options right now means all we have left are vaccines and a couple of antiviral therapies.
"If you know anyone who has cancer or is immunocompromised for some other reason, it's pretty scary not having this," Luban said. "It's a big problem."