As autumn bleeds into winter, public health officials are anticipating another wave of COVID infections, just like the two years previous — with some experts anticipating as many as 100 million infections this time around.
In spite of evidence to the contrary, President Joseph Biden recently declared that the COVID pandemic is "over," before walking back those comments. What Biden allegedly meant to say is that we're not in the same situation we were before, which is mostly true. Compared to the start of the pandemic, we have far more tools to fight COVID than ever before — especially the vaccines, but also antiviral drugs and monoclonal antibodies. And of course, masks still work at preventing infection.
Even the World Health Organization (WHO) seems to think these defenses will be enough in the coming months.
"We have never been in a better position to end the pandemic. We are not there yet, but the end is in sight," Dr. Tedros Adhanom Ghebreyesus, the WHO's director-general, said in a September 14th press conference. "We can see the finish line. We are in a winning position but now is the worst time to stop running."
Of course, all of this optimism could be erased overnight if another brutal COVID variant emerges, not unlike what happened with the delta and omicron variants. In both cases, the loosening of pandemic restrictions turned out to be premature, followed by surges in infections, deaths and the disabling condition known as long COVID.
But whether a new variant will emerge remains an open question. SARS-CoV-2, the virus responsible for COVID, is constantly mutating. Every new infection gives the pathogen new opportunities to evolve evasive maneuvers against vaccines and medications or immunity acquired from past infections.
Right now, the most dominant strain of SARS-CoV-2 is BA.5, a lineage of omicron that emerged last April and has made up the majority of cases through late spring and summer. As of September 17, BA.5 was responsible for about 85 percent of cases, according to the Centers for Disease Control and Prevention (CDC).
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There's a lot we still don't know about BA.5, but it is considered the most contagious version of the virus yet known — and also the most contagious virus to ever exist by most metrics, according to scientists. Compared to other strains, so far BA.5 seems to be less likely to trigger hospitalization or death, although the risk is still very real. Developing long COVID is also a substantial risk, especially in the unvaccinated or following multiple infections.
Could a new variant dethrone BA.5? It's possible, but we don't know just yet. However, scientists are keeping a watchful eye out for what may emerge.
One of these omicron subvariants is called BA.2.75, but that name was a little overlong, so it was dubbed "Centaurus" by Twitter folks and the media ran with it. Concerned by its ability to evade immunity, making vaccines and prior COVID infections less protective, the WHO began tracking Centaurus in July. But now it seems to have all but fizzled out (only accounting for 1.3 percent of infections, as of Sept 17) and Centaurus is no longer considered a major threat. For now.
However, attention has shifted to one of Centaurus' kids. An off-shoot called BA.2.75.2 is now causing concern among health experts because it exhibits "extensive escape" from neutralizing antibodies. BA.2.75.2 is "the most neutralization resistant variant evaluated to date," according to a study that hasn't yet been peer-reviewed, but is still alarming many experts.
BA.2.75.2 (perhaps we should call it Centaurus 2) features a spike protein that binds to human cells more tightly than any other variant so far, Dr. Raj Rajnarayanan, assistant dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Arkansas, told Fortune.
Health officials are also monitoring BA.188.8.131.52, a strain that is often shortened to just BF.7, which is currently spreading in multiple countries across Europe. In Belgium alone, BF.7 makes up 25 percent of cases. While only 1.7 percent of cases in the U.S. are linked to BF.7, that still makes up 12 percent of the global total. And the evidence from other nations suggests the U.S. may be next to see a comparable increase.
"The same growth advantage in multiple countries makes it reasonable to think that BF.7 is gaining a foothold," Dr. Stuart Ray, vice chair of medicine for data integrity and analytics at Johns Hopkins Department of Medicine, told Fortune.
So far, the most prevalent strain after BA.5 is BA.4.6, which accounts for 10.3 percent of cases in the U.S. and is also spreading in the U.K. While there are only seven amino acid differences throughout the entire genome between the two viruses, even small alterations like this can have a big impact. Notably, BA.4.6 carries a mutation to the spike protein called R346T that, in other COVID viruses, has been found to help it escape immunity. But we won't know how well our defenses do against it until more time passes.
"We will not know the potential impact of BA.4.6 for some time," William Haseltine, president of ACCESS Health International, wrote in Forbes. "It may fade into relative inconsequence along with many variants that have come before it, but it may also emerge as the newest variant of concern. As such, we must prepare for the latter, continuing to identify and develop treatments that can neutralize the variant."
It's hard to rank which subvariant could be the most concerning. BF.7, Centaurus 2, BA.4.6 or even a yet-to-be-discovered variant could dominate COVID cases this year, but until we have more data, it's difficult to forecast what this winter will look like. And it may be getting harder to predict where the next variant could come from or how dangerous it could be. The World Health Organization on Thursday said it was tracking about 200 omicron lineages, but warned that it was losing the ability to identify and track new COVID variants as many countries roll back testing and surveillance measures.
So while we clearly have the tools to monitor and prevent COVID infections, they aren't any good unless we use them. Right now, it's not clear how the new booster vaccines will fare against emerging COVID variants. That means that even if the President wants to say this pandemic is over, it wouldn't take much to land us close to where we started.