What is the point of travel bans?

It has been a week since South Africa reported the omicron coronavirus variant, and travel bans have been the most visible public health measure that followed. For instance, the US barred entry of only those coming in from African countries even though omicron has been detected in Europe, the UK, and Israel, too. “Travel bans could potentially be prudent if a country needs to buy time to scale up public health measures,” said Brian Wahl, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health.