3 possible scenarios for BA.2.86

Scenario 1: BA.2.86 surges worldwide

The worst-case scenario, and the least likely one, according to Zhang, is one in which BA.2.86 surges around the world similar to how omicron did in 2021.

However, according to Thomas Peacock, a virologist at the Pirbright Institute, BA.2.86 doesn't seem to be spreading as quickly as omicron did. "If it had been very fast, we probably would have known by now," he said, noting that it only took three or four days for Omicron to become obvious around the world.

Experts aren't willing to totally rule out a potential surge, however. Given that COVID surveillance isn't a priority anymore, labs around the world are only sequencing about 1% of what they were two years ago, Peacock said, making it more likely for a variant like BA.2.86 to spread silently.

Even if there's an omicron-like surge, collective immunity to the coronavirus should act as a buffer, Zhang writes. BA.2.86 appears to have reinfection capabilities similar to omicron, according to a preliminary analysis by Jesse Bloom, a virologist at the Fred Hutchinson Cancer Center, but Bloom noted there are big differences 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 said. "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."

Scenario 2: BA.2.86 spreads like other post-omicron variants

Another potential scenario is one in which BA.2.86 operates similarly to other post-omicron variants, like BA.2, BA.2.12.1, and XBB.1.5, where it becomes transmissible enough to beat out a previous variant but not transmissible enough to cause a new surge, Zhang writes.

However, if BA.2.86 continues to circulate, it could pick up new mutations that could give it an advantage, like XBB.1.5. That variant's predecessor wasn't particularly successful at first, as its spike protein bound weakly to receptors in human cells, Peacock said. But then, the variant acquired a mutation in its spike protein that compensated for that shortcoming, allowing XBB.1.5 to become more dominant.

Scenario 3: BA.2.86 disappears

It's also possible that BA.2.86 could simply fizzle out and disappear, Zhang writes.

Experts believe that highly mutated variants like BA.2.86 are the results of chronic infections in immunocompromised patients, where the virus remains in the body for a long time, attempting to figure out new ways to dodge the immune system.

It could end up with new mutations that would make its spike protein less recognizable to antibodies, but those mutations could also make the spike protein less functional, making the variant less effective at transmitting from person to person, Zhang writes.

"Variants like that have been identified over the last few years," Bloom said. "Often there's one sample found, and that's it. Or multiple samples all found in the same place." (Zhang, The Atlantic, 8/29)

Pfizer and  Moderna have both separately announced that their updated COVID-19 vaccines, which are slated to become available this fall, are effective against new coronavirus variants that are now circulating, including EG.5.1, nicknamed "Eris," and FL.1.5.1, nicknamed "Fornax."