The Africa Centres for Disease Control and Prevention said it strongly discouraged imposing travel bans on people coming from countries where the variant was reported.

Do travel restrictions work?

They might buy countries more time to speed up vaccinations and introduce other measures, like masking and social distancing, but they are highly unlikely to prevent the entry of new variants, said Mark Woolhouse, a professor of infectious diseases at the University of Edinburgh.

“Travel restrictions can delay but not prevent the spread of a highly transmissible variant,” he said.

Johns Hopkins University infectious disease specialist Dr. Amesh Adalja said travel restrictions only give the public a false sense of security and should stop being the “knee-jerk” reaction by public officials. Adalja noted imposing restrictions makes politicians “look as if they’re doing something” but does not make sense when countries now have countermeasures such as rapid tests and vaccines.

Meanwhile, Sweden’s chief epidemiologist, Anders Tegnell, told a local news agency he does not believe that a travel ban would have any major effect, other than for countries with direct flights to the affected areas. “It is basically impossible to keep track of all travel flows,” he told the Expressen newspaper.

Jeffrey Barrett, director of Covid-19 Genetics at the Wellcome Sanger Institute, said he thought that the early detection of the new variant could mean restrictions taken now would have a bigger impact than when the Delta variant first emerged.

“The surveillance is so good in South Africa and other nearby countries that they found this [new variant], understood it was a problem and told the world very fast about it,” he said. “We may be at an earlier point with this new variant so there may still be time to do something about it.”

However, Barrett said harsh restrictions would be counterproductive and that the South African officials should not be punished for alerting the world to the new variant. “They’ve done the world a service and we must help them, not penalise them for this.”

What does the science say?

Sharon Peacock, who has led the genetic sequencing in Britain at the University of Cambridge, said any decisions to restrict travel were political decisions, not scientific ones. She emphasised that there was still great uncertainty about the new variant, including whether it is actually more infectious or deadly. Although some of the mutations detected appeared worrying, she said there is still no proof that the new variant is any more lethal or transmissible than previous versions.

“It’s possible to keep infection out, but you would need very, very severe restrictions and only some countries would be willing to do this,” she said.

“Buying time is important and worthwhile, but this is a decision for policymakers,” she said. “At the moment, we won’t have any definitive scientific answers for a few weeks.”

What about the economy?

If there is anything the global economy did not need, it is more uncertainty.

“The most worrying thing about the new strain at the moment is how little we know about it,’’ said Craig Erlam, senior market analyst for the currency trading firm Oanda.