All of that suggests that in a world dominated by Omicron, the proportion of infected people who die could fall well below the 1% to 2% death rate that’s prevailed across much of the pandemic. Likewise, the surges in hospitalizations that have strained healthcare systems and exhausted medical professionals could be dampened.

If cases tended to be more mild and COVID-19 vaccines could still protect the most vulnerable people from dying, a kinder, gentler Omicron — even a highly contagious one — could be the break health officials and scientists have been waiting for…

COVID-19 death rates across South Africa also have fallen precipitously despite the Omicron wave. If there is no massive surge in hospitalizations or deaths in the next two to three weeks, that “may well mark [a] turning point in [the] pandemic,” Dr. Shabir Madhi, an infectious-disease expert at the University of the Witwatersrand, wrote on Twitter.

A variant that combines high transmissibility with greatly reduced virulence would be welcomed by many scientists. If an infection with Omicron is unlikely to make a patient severely ill but leaves some immunity in its wake, it could act as a “natural vaccine,” said Dr. Bruce Walker, an immunologist and founding director of the Ragon Institute in Cambridge, Mass.