The discovery of a new coronavirus variant named Omicron triggered global alarm on Friday as countries rushed to suspend travel from southern Africa and stock markets on both sides of the Atlantic suffered their biggest falls in more than a year.
The World Health Organisation (WHO) said Omicron may spread more quickly than other forms and preliminary evidence suggested there is an increased risk of reinfection.
Epidemiologists warned travel curbs may be too late to stop Omicron from circulating globally. The new mutations were first discovered in South Africa and have since been detected in Belgium, Botswana, Israel and Hong Kong.