Travellers exit the coronavirus disease (COVID-19) pandemic testing area at Ben Gurion International Airport as Israel imposes new restrictions near Tel Aviv, Israel, November 28, 2021. (Photo: REUTERS/Amir Cohen)

The World Health Organization (WHO) said it was not yet clear whether Omicron, first detected in Southern Africa, is more transmissible than other variants, or if it causes more severe disease. The WHO said understanding the level of severity of Omicron "will take days to several weeks".

The detection of Omicron triggered global alarm as governments around the world scrambled to impose new travel curbs.

Omicron, dubbed a "variant of concern" last week by the WHO that is potentially more contagious than previous variants, has now been detected in Australia, Belgium, Botswana, Britain, Denmark, Germany, Hong Kong, Israel, Italy, the Netherlands, France, Canada and South Africa.