The coronavirus could get worse

We can’t precisely predict what worse will look like. 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. No one yet knows exactly where that tipping point is—just that we will probably, eventually, collide with it…

The cyclical nature of this game might sound disheartening. But nothing will ever put us back at square one. Even as the virus evolves away from us, we can give chase. As immunity builds, our dalliances with the virus will trend milder, shorter, and less frequent. With vaccination on our side, we’re giving the virus fewer turns at the board, and slowing the pace at which the game is played. Although we can’t yet trounce SARS-CoV-2 for good, we can buy ourselves time to make our next decisive move.