Coronavirus spiked, and then sputtered, at the Winter Games.

The “closed loop” is a bubblelike environment in which athletes, officials, broadcasters, journalists and a large Games work force eat, sleep, work and compete.Credit...Doug Mills/The New York TimesAs athletes, journalists and others prepared to travel to Beijing amid the Omicron surge, and China carried out sweeping lockdowns to keep the highly contagious coronavirus variant from spreading, the world held its breath to see if the virus would plunge the Winter Games into chaos.

Cases spiked at the beginning of the Games as many of those heading to Beijing tested positive even before arriving. But cases never soared within the closed environment known as the Olympic bubble, as had been…