![]() ![]() "A virus' job is just to keep propagating," says Green. For example, in the case of a respiratory virus like COVID-19, the ability to travel longer distances in the air, and to latch more firmly onto cells in the nasal passage, would likely make a new strain a better contender to become a widely spreading variant. What specific features will help the mutation become a better replicator and spreader in the population is determined by the environment. To become a significant variant, a mutated virus has to out-replicate the far more numerous copies of the virus that already predominate in the population, and to do that it needs features that give it big advantages. Most of the mutations we've seen so far represent tweaks to these spikes, which means it only takes a minimal change within any of the few viral genes that control the spikes to create a newly threatening mutation.īut even when a virus hits the jackpot with a mutation that sharpens its ability to wreak havoc, that doesn't mean a dangerous new variant has emerged. What's more, much of what makes the virus dangerous has to do with a relatively small portion-the so-called spike proteins that protrude from its surface and enable the virus to latch onto and penetrate human cells. Read more COVID-19 Could Increase Dementia, Other Brain Disorders for Decades to Comeīut once in a while-perhaps every million trillion times-a random mutation confers some potentially dangerous new characteristic. "Having billions of people infected presents a breeding ground for variants unlike anything we've ever seen with these sorts of viruses," he says. Even more important, he adds, scientists underestimated the sheer scale the pandemic would eventually achieve-a critical factor, because the more people a virus infects, the more opportunities it has to develop significant mutations. In the absence of data, scientists assumed it would follow other viruses in being relatively slow to spin off much more contagious mutations. But unlike most other pathogens, Eisen notes SARS-CoV-2 was largely unknown when it emerged. It may seem surprising that scientists were caught off-guard by the rapid emergence of a more dangerous variant. "But we didn't think the mutations would so strikingly affect transmissibility and possible evasion of immunity." ![]() "All coronaviruses mutate, and we knew this one was mutating, too," says Sharone Green, a physician and infectious disease researcher at the University of Massachusetts Medical School. NIAIDĭelta, more than any other variant, has reset scientists' understanding of how quickly a virus can evolve into devastating new forms. "We probably only need to worry about it on a timescale of about five years." Today he calls Delta and other COVID-19 variants "the pandemic within the pandemic."Ĭolorized scanning electron micrograph of an apoptotic cell (tan) heavily infected with SARS-COV-2 virus particles (orange), isolated from a patient sample. "They don't seem to make much of a difference," said Richard Neher, an evolutionary biologist at Switzerland's University of Basel, in August last year. Early in the pandemic, most experts closely studying COVID-19 mutations downplayed the notion that variants would cause such serious problems. "The next variant," says Osterholm, "could be Delta on steroids." Caught Off-Guard ![]() Its extreme contagiousness, with room to run freely through the tens of millions of Americans who haven't been vaccinated and millions more who have no access to vaccines in developing countries, has good odds of turning into something even more troublesome. Delta has already shown how much worse things can get. The odds are not high that we will see such a triple threat, but experts can't rule it out. But it's a good time to wonder: Just how destructive can these variants get? Will future variants expand their attack from the lungs to the brain, the heart and other organs? Will they take a page from HIV and trick people into thinking they've recovered, only to make them sick later? Is there a Doomsday variant out there that shrugs off vaccines, spreads like wildfire and leaves more of its victims much sicker than anything we've yet seen? It's too soon to say whether Lambda will turn out to be the next big, bad thing that COVID-19 unleashes on us. Read more Delta-Variant COVID Questions Answered, From Booster Shots to Returning to the Office
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