How Bad Could BA.2.86 Get?

Atlantic

Until the future of the new COVID variant becomes clear, three scenarios are still possible.

Since Omicron swept across the globe in 2021, the evolution of SARS-CoV-2 has moved at a slower and more predictable pace. New variants of interest have come and gone, but none have matched Omicron’s 30-odd mutations or its ferocious growth. Then, about two weeks ago, a variant descended from BA.2 popped up with 34 mutations in its spike protein—a leap in viral evolution that sure looked a lot like Omicron. The question became: Could it also spread as quickly and as widely as Omicron?

This new variant, dubbed BA.2.86, has now been detected in at least 15 cases across six countries, including Israel, Denmark, South Africa, and the United States. This is a trickle of new cases, not a flood, which is somewhat reassuring. But with COVID surveillance no longer a priority, the world’s labs are also sequencing about 1 percent of what they were two years ago, says Thomas Peacock, a virologist at the Pirbright Institute. The less surveillance scientists are doing, the more places a variant could spread out of sight, and the longer it will take to understand BA.2.86’s potential.

eacock told me that he will be closely tracking the data from Denmark in the next week or two. The country still has relatively robust SARS-CoV-2 sequencing, and because it has already detected BA.2.86, we can now watch the numbers rise—or not—in real time. Until the future of BA.2.86 becomes clear, three scenarios are still possible.

The worst but also least likely scenario is another Omicron-like surge around the world. BA.2.86 just doesn’t seem to be growing as explosively. “If it had been very fast, we probably would have known by now,” Peacock said, noting that, in contrast, Omicron’s rapid growth took just three or four days to become obvious.

Scientists aren’t totally willing to go on record ruling out Omicron redux yet, if only because patchy viral surveillance means no one has a complete global picture. Back in 2021, South Africa noticed that Omicron was driving a big COVID wave, which allowed its scientists to warn the rest of the world. But if BA.2.86 is now causing a wave in a region that isn’t sequencing viruses or even testing very much, no one would know.

Even in this scenario, though, our collective immunity will be a buffer against the virus. BA.2.86 looks on paper to have Omicron-like abilities to cause reinfection, according to a preliminary analysis of its mutations by Jesse Bloom, a virologist at the Fred Hutchinson Cancer Center, in Washington, but he adds that there’s a big difference between 2021 and now. “At the time of the Omicron wave, there were still a lot of people out there that had never been either vaccinated or infected with SARS-CoV-2, and those people were sort of especially easy targets,” he told me. “Now the vast, vast majority of people in the world have either been infected or vaccinated with SARS-CoV-2—or are often both infected and vaccinated multiple times. So that means I think any variant is going to have a very hard time spreading as well as Omicron.”

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