Writing for The Atlantic, Katherine Wu details four potential shapes the next Covid-19 variant could take—and explains how each scenario would elicit a specific public health response.

Radio Advisory: What surprised us most about Covid-19, two years later

'The sharpshooter'

In the worst-case (and least likely) scenario, the next variant would be more transmissible, more deadly, and more capable of evading the defenses from vaccines and prior infection with other Covid-19 variants, according to Wu.

In this scenario, Wu writes, we could see high rates of severe Covid-19—even among immunized individuals. In fact, additional boosters might not even provide sufficient protection.

Unfortunately, this type of virus might mutate so much that it could go undetected by some of our diagnostic tests—and many antibody-based treatments may stop working altogether.

As a result, hundreds of thousands of people in the United States alone could lose their lives in just a few months, and countless others would be hospitalized or experience long Covid. This scenario would be a near-reversion to "the first year of the pandemic," said Crystal Watson, a senior associate at the Johns Hopkins Center for Health Security.

To combat this type of variant, Wu says manufacturers would immediately need to start working on a new vaccine—a process that would take at least three months. Until a new vaccine could be manufactured and distributed, Americans would have to rely on safety measures, including high-quality masks, restricted travel, and capacity limits—and possibly even brief closures at public venues like restaurants, bars, and gyms.

However, "a variant quite this bad would be hard to come by. Viruses can't rejigger their genomes infinitely—not if they want to keep efficiently infecting their preferred hosts," she writes.

According to John Wherry, an immunologist at the University of Pennsylvania, it is not very difficult for a virus to slip out of the grasp of antibodies, but "just statistically speaking, I don't think it's possible to escape T-cell immunity."

'The escape artist and the brute'

In a less "catastrophic" scenario, Wu says the next variant could still impact a significant portion of the population by "ratcheting up one trait at a time." For example, a variant that causes a "juice-up in immune evasion," or a variant that causes a "surge in virulence."

"All else equal, each could spark waves of serious disease and push the health care system back to a breaking point," Wu adds.

With an evasive variant, the coronavirus would face enormous pressure to locate an "immunological escape hatch." This scenario could result in an even more dramatic version of the recent omicron wave—no one would be immune to the variant or its effects. By the numbers alone, this scenario could result in increased hospitalizations and could be even more deadly than omicron. 

"Depending on the extent to which the variant eroded vaccine effectiveness, especially against hospitalization and death, we might still need to update our shots and launch a massive revaccination campaign," Wu writes.

According to Wu, a more virulent variant could be easier to address. In this scenario, public health officials would likely focus on shielding the most vulnerable populations, including the unvaccinated, the elderly, the immunocompromised, and those with heavy or frequent exposures to the virus.

'The sprinter'

In another scenario, a mutation—or combination of several mutations—could make the virus more transmissible. However, without an accompanying increase in virulence or extreme immune evasion, "I'm not sure there'd be much of a response, to be honest with you," Watson said.

As a result, Wu writes, "[s]ome people might feel motivated to sign up for a booster. A few localities might push for masking again. Or not." 

"I have a hard time believing anyone's going to care, unless there's more severity," said Adam Lauring, a virologist at the University of Michigan.

We could potentially see this variant's annual hospitalization and death rates mirror the flu's. However, "souped-up transmissibility is an insidious parlor trick," Wu writes. "It helps viruses catch entire populations off guard. Even a somewhat defanged variant can sow chaos if it's given the opportunity to spread far and wide enough, and find the vulnerable among us."

Even if the virus becomes completely benign, total complacency could still be dangerous. A virus that spreads freely suddenly has "more hosts in which to evolve," said Jemma Geoghegan, an evolutionary virologist at the University of Otago in New Zealand.

"We can't say when the next threat will appear, or how formidable it will be. But we do have some control over its emergence: The more chances we give the virus to infect us, the more chances we give it to change itself again," Wu writes.

Ultimately, each variant will require a slightly different response—and the ideal approach will largely depend on "how sick are people getting, and which people are getting sick," said Angela Shen, a vaccine-policy expert at Children's Hospital of Philadelphia. (Wu, The Atlantic, 3/9)