By ELIZ­A­BETH ME­LIMOPOU­LOS, Al Jazeera

■ The World Health Or­ga­ni­za­tion names new coro­n­avirus vari­ant Omi­cron and des­ig­nates it as a ‘vari­ant of con­cern’ ■

Glob­al au­thor­i­ties have re­act­ed with alarm to a new coro­n­avirus vari­ant de­tect­ed in South Africa, with the Eu­ro­pean Union and the Unit­ed King­dom among those tight­en­ing bor­der con­trols as re­searchers sought to find out if the mu­ta­tion was vac­cine-re­sis­tant.

Hours af­ter the UK banned flights from South Africa and neigh­bour­ing coun­tries and asked trav­ellers re­turn­ing from there to quar­an­tine, the World Health Or­ga­ni­za­tion (WHO) cau­tioned against hasty mea­sures and a South African sci­en­tist la­belled Lon­don’s de­ci­sion a symp­tom of “vac­cine apartheid”.

Eu­ro­pean Com­mis­sion chief Ur­su­la von der Leyen said the EU al­so aimed to halt air trav­el from the re­gion and sev­er­al oth­er coun­tries in­clud­ing In­dia, Japan and Is­rael tough­ened curbs.

The Unit­ed States top in­fec­tious dis­ease of­fi­cial An­tho­ny Fau­ci said no de­ci­sion had been made on a pos­si­ble US trav­el ban.

The WHO said it would take weeks to de­ter­mine how ef­fec­tive vac­cines were against the vari­ant, which was first iden­ti­fied this week.