Before the Olympics began, Japan had feared that the 2020 Games, with thousands of officials, media and athletes descending on Tokyo in the middle of a pandemic, might spread COVID-19, introduce new variants and overwhelm the medical system.

But as the Games draw near their end, the infection numbers from inside the Olympic "bubble" — a set of venues, hotels and the media center to which those coming for the Games had been mostly confined — tell a different story.

Featuring more than 50,000 people, what amounted to possibly the largest global experiment of this kind since the pandemic began, appears to have largely worked, organizers and some scientists say, with only a sliver of those involved infected.