Beijing's Olympic 'bubble' will be the most ambitious Covid quarantine ever attempted. Will it work?

The Winter Games is just two weeks away and outside Beijing's Olympic venues, the banners and decorations are up. But so too are long rows of metal fences and guard posts, dividing the Chinese capital and barring anyone without an official Covid-safe pass.Having been largely sealed off from the world for two years, Beijing is bracing itself for the arrival of thousands of foreign Olympians,