There is no playbook for evolution. Delta could continue to ratchet up its rate of spread, or it could be ousted by another super-infectious variant. But the speed that has powered Delta’s transmission for months probably can’t sustain SARS-CoV-2 forever, at least not on its own.
Humanity’s collective immunity to the virus is growing, which means the next variants we encounter might be better off taking a tack that relies a lot more on stealth.
“There’s some sort of tipping point where immune evasion becomes a bigger fitness advantage than transmission,” Stephen Goldstein, an evolutionary virologist at the University of Utah, told me.
A large fraction of us, especially in vaccine-wealthy countries such as the United States, now have some degree of immunity, simultaneously suppressing the pathogen’s ability to pass among us and pressuring it to circumvent those shields. Our defenses are upping the ante for the virus. And the virus will likely rise to meet it.
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The cyclical nature of this game might sound disheartening. But nothing will ever put us back at square one…. As immunity builds, our dalliances with the virus will trend milder, shorter, and less frequent.
