BA.5 Covid Variant Becomes Dominant

SARS-CoV-2, repped by the Omicron clan, is now spewing out globe-sweeping subvariants at a blistering clip. In the United States, the fall of BA.2 and BA.2.12.1 have overlapped so tightly with the rise of BA.5 that the peaks of their surges have blended into one. And a new, ominous cousin, BA.2.75, is currently popping in several parts of the world.



At the same time, our countermoves are sluggish at best. Pathogens don’t spread or transform without first inhabiting hosts. But with masks, distancing, travel restrictions, and other protective measures almost entirely vanished, “we’ve given the virus every opportunity to keep doing this,” says David Martinez, a viral immunologist at the University of North Carolina at Chapel Hill.

More variants mean more infections; more infections mean more variants. It’s true that, compared with earlier in the pandemic, hospitalization and death rates remain relatively low. But a high rate of infections is keeping us in the vicious viral-evolution cycle. “The main thing is really this unchecked transmission,” says Helen Chu, an epidemiologist and vaccine expert at the University of Washington. We might be ready to get back to normal and forget the virus exists. But without doing something about infection, we can’t slow the COVID treadmill we’ve found ourselves on.

The speed at which a virus shape-shifts hinges on two main factors: the microbe’s inherent capacity for change, and the frequency with which it interacts with hospitable hosts.

Coronaviruses don’t tend to mutate terribly quickly, compared with other RNA viruses. And for the first year or so of the pandemic, SARS-CoV-2 stuck to that stereotype, picking up roughly two mutations a month. But then came Alpha, Delta, Omicron and its many subvariants—and SARS-CoV-2 began to outstrip the abilities of even flu viruses to birth versions of itself that vaccinated and previously infected bodies can’t easily recognize. BA.1 sported dozens of typos in its genome; BA.2 was able to rise quickly after, in part because it carried its own set of changes, sufficient to stump even some of the defenses its predecessor had raised. The story was similar with BA.2.12.1—and then again with BA.4 and BA.5, the wonkiest-looking versions of the virus that have risen to prominence to date.

Three things, Koelle told me, could slow SARS-CoV-2’s roll. First, the virus’s genome could get “a little more brittle, and less accepting of mutations,” she said. Maybe, for instance, the microbe’s ability to switch up its surface will hit some sort of ceiling. But Koelle thinks it’s unwise to count on that.

Instead, we, the virus’s hosts, could give it fewer places to reproduce, by bolstering immunity and curbing infections. On the immunity front, the world’s nowhere yet near saturated; infections will continue, and make the average person on Earth a crummier place to land. Better yet, vaccinations will shore up our defenses. Billions of people have now received at least one dose of a COVID-19 shot—but there are still large pockets of individuals, especially in low-income countries, who have no shots at all. Even among the vaccinated, far too few people have had the three, four, or even five injections necessary to stave off the worst damage of Omicron and its offshoots. Simply getting people up to date would increase protection, as could variant-specific updates to vaccine recipes, likely due soon in the U.S. and European Union.

But the appetite for additional shots has definitely ebbed, especially in the U.S. Retooled recipes also won’t see equitable distribution around the globe. They may even end up as a stopgap, offering only temporary protection until the virus gets “pushed to a new point” on its evolutionary map and circumvents us again, Hill said.

Which leaves us with coordinated behavioral change—a strategy that exactly no one feels optimistic about. Precautionary policies are gone; several governments are focused on counting hospitalizations and deaths, allowing infections to skyrocket as long as the health-care system stays intact. “Everyone just wants some sense of normalcy,” UW’s Roychoudhury said. Even many people who consider themselves quite COVID-conscious have picked up old social habits again. “The floodgates just opened this year,” Martinez said. He, too, has eased up a bit in recent months, wearing a mask less often at small gatherings with friends, and more often bowing to peer pressure to take the face covering off. Ajay Sethi, an infectious-disease
epidemiologist at the University of Wisconsin-Madison, still works at home, and avoids eating with strangers indoors. He masks in crowded places, but at home, as contractors remodel his bathrooms, he has decided not to—a pivot from last year. His chances of suffering from the virus haven’t changed much; what has is “probably more my own fatigue,” he told me, “and my willingness to accept more risk than before.”

The global situation has, to be fair, immensely improved. Vaccines and treatments have slashed the proportion of people who are ending up seriously sick and dead, even when case rates climb. And the virus’s pummel should continue to soften, Hill told me, as global immunity grows. Chu, of the University of Washington, is also optimistic that SARS-CoV-2 will eventually, like flu and other coronaviruses, adhere to some seasonality, becoming a threat that can be managed with an annually updated shot.

But the degree to which the COVID situation improves, and when those ease-ups might unfold, are not guaranteed—and the current burden of infection remains unsustainably heavy. Long COVID still looms; “mild” sicknesses can still leave people bedridden for days, and take them away from school, family, and work. And with reinfections now occurring more frequently, individuals are each “more often rolling the die” that could make them chronically or seriously ill, Hodcroft, of the University of Bern, told me. In the Northern Hemisphere, that’s all happening against the backdrop of summer. The winter ahead will likely be even worse.

And with transmission rates this high, the next variant may arrive all the sooner—and could, by chance, end up more severe. “How much do we want to restrict our own freedoms in exchange for the injury that may be caused?” Hodcroft said. “That’s something that hard science can’t answer.”