“I think we need to be prepared for the possibility that this could be at least as bad as any previous wave that we’ve seen,” said Justin Lessler, an epidemiologist at the University of North Carolina at Chapel Hill. “We need to be thinking about what the plan is if things get bad.”…

The population of the United States is older, and has a different pattern of vaccination and prior infection, than South Africa’s population, she noted.

And, she said, “even if infection is mild in many individuals, it’s not going to be mild in everyone.”

If Omicron spreads rapidly and infects huge swaths of the population at once, it could still sicken enough people to overwhelm health care systems, some of which are already struggling to manage a surge of Delta cases.