China's meticulous plans to prevent an Olympics-seeded COVID-19 outbreak by sealing all participants inside a "closed loop" for the upcoming Winter Games will be tested by the emergence of the highly infectious omicron variant.

The country has reported only a handful of omicron cases and has largely succeeded in containing COVID-19 since it first emerged in the central city of Wuhan two years ago, thanks to a zero-tolerance policy that includes rigorous contact tracing, strict targeted lockdowns, and travel curbs that have drastically cut international arrivals.

But more than 2,000 international athletes are set to come to China for the Games that start Feb. 4, plus 25,000 other "stakeholders," a large number from overseas. Organizers did not say how many of those people would be in the closed loop.