The new COVID-19 variant first detected in South Africa was given the name Omicron by the World Health Organization on Friday.
An advisory panel classified Omicron as a highly transmissible virus of concern and gave it its name under its Greek-letter system.
It marks the first time in months that WHO has classified a COVID-19 variant with such a name – and is only the fifth variant to be given the designation amid the pandemic.
It is the same category that includes the Delta variant, which quickly became the world’s most prevalent strain.
It could take weeks for scientists to fully understand the variant’s mutations, but the WHO panel said early evidence suggests an increased risk of reinfection.
Health authorities are rushing to determine if Omicron is more transmissible or infectious than other variants — and if the vaccines are effective against it.
The advisory panel convened on Friday after South African scientists alerted them to the new variant earlier this week.
Scientists first detected the Omicron variant on Tuesday in samples dated from Nov. 14-16.
The discovery sent a chill through much of the world as countries rushed to ban flights from southern Africa and markets fell sharply.
Britain has already put six African countries, including South Africa, Namibia, Lesotho, Botswana, Eswatini and Zimbabwe, on its red list – which means arriving travelers have to quarantine for 10 days in a government facility.
The EU said Friday it would move to ban flights from southern African countries.
Dr. Anthony Fauci, however, said the US needed more data on the variant before deciding on a travel ban.
Fauci told CNN that US scientists would be speaking with South African counterparts later on Friday.