The successful completion of the Beijing 2022 Winter Olympics was a "great victory" with strong measures to control the spread of COVID-19, said Han Zirong, vice president and secretary-general of the Beijing Organizing Committee for the event, in a press conference on Sunday.

"No cross-infection happened between foreign participants and local people," she explained. "We achieved a great balance between quality and safety."

To ease people's COVID-19 concerns, the organizers created what they call a "closed loop" around all the participants of the Games – no one leaves, and no one enters.

Watch: Pandemic prevention official explains 'closed-loop' management

This method initially drew some doubt from foreigners, with some athletes worried that strict COVID-19 control measures may affect their status and performance.

But days after they entered the loop, many athletes realized it did not disturb their daily routine.

"It's totally normal. Like it's absolutely normal that you would have hundreds of people in PPE all around you," Team USA luger Chris Mazdzer was quoted as saying by NBC.

President of the International Olympic Committee (IOC) Thomas Bach hailed the closed-loop management system as "very successful as it has made everyone in the bubble feel safe and comfortable."

The closed loop may sound like a bubble limiting people's freedom, but it turned out that life inside the bubble could be pretty interesting. Besides their daily coronavirus tests, athletes and officials could enjoy the special Lantern Festival celebration and try out the fancy, hi-tech mobile toilets.

IntraHealth International, a global health nonprofit based in the U.S., evaluated the bubble's performance from three perspectives, and the results are highly positive.