A coronavirus variant recently identified in South Africa is leading to a new round of travel restrictions just as many had finally begun to ease. The risks of the new variant are largely unknown, but governments around the world are not waiting for scientists to better understand the variant to impose flight bans. The moves have renewed a debate over whether these travel restrictions work to prevent the spread of new variants. Some say at best the restrictions can buy time. At worst, they do little to stop the spread and give a false sense of security.