Hong Kong announced a ban on passengers from more than 150 nations transiting its airport as China ramps up strict anti-virus travel measures ahead of the Winter Olympics, Reuters reports.

Hong Kong business hub ranks territories into categories based on how widespread their Covid-19 infections are, with 153 countries currently classified as Group A — from which arrivals must spend 21 days in quarantine.

Last week, it banned incoming flights from Pakistan, India, Australia, Canada, France, the Philippines, Britain and the United States, including interchanges.