Photo used for illustrative purpose.
The variant's global spread suggests it could have a major impact on the COVID-19 pandemic, and the time to contain it is now before more Omicron patients are hospitalised, WHO director-general Tedros Adhanom Ghebreyesus said.
"We call on all countries to increase surveillance, testing and sequencing," he told a media briefing. "... Any complacency now will cost lives."
Tedros Adhanom Ghebreyesus speaks during an event. File
The WHO noted early evidence from BioNTech and Pfizer of the effectiveness of their vaccine against Omicron.
The German and US companies said on Wednesday a three-shot course of their COVID-19 vaccine was able to neutralise the new Omicron variant in a laboratory test, while two doses resulted in lower neutralising antibodies by a factor of 25.
Warning against jumping to conclusions from the test, the WHO's chief scientist said it was too soon to say whether the reduction in neutralising antibodies meant the shot was less effective.
"We do not know that," Soumya Swaminathan told the briefing, adding that coordinated global research efforts were needed.
The WHO also said it would publish a review of its stance on booster doses within days, but with vaccination rates worryingly low in much of the developing world, administering primary doses — rather than boosters — remained its priority. "Wholesale boosters are not the solution," Swaminathan said.
WHO chief scientist Soumya Swaminathan said that the variant was successfully evading some immune responses, meaning that the booster programmes being rolled out in many countries ought to be targeted towards people with weaker immune systems.
Omicron appears to be better at evading antibodies generated by some COVID-19 vaccines but there are other forms of immunity that may prevent infection and disease, WHO officials said.
More than 8.53 million people have been reported infected by the novel coronavirus globally and 453,834 have died, a Reuters tally showed as of 1326 GMT on Friday.
"There is currently no evidence that people who have recovered from #COVID19 and have antibodies are protected from a second infection," WHO said in a statement.
World leaders must not politicise the coronavirus pandemic but unite to fight it, the head of the World Health Organisation (WHO) warned on Monday, reminding all that the pandemic is still accelerating and producing record daily increases in infections.
Sheikh Mohammed said 'Pursuant to the directives of my brother, the President of the UAE, all work teams have been instructed to follow up the effects of the earthquake.'
Sheikh Mohamed directed the dispatch of a search and rescue team and the provision of urgent relief supplies and emergency aid to those affected by the earthquake in Syria to help families in the hardest-hit areas.
Frank Hogerbeets, a Dutch researcher, had warned in tweeted tweeted on Feb.3 that 'sooner or later there will be a ~M 7.5 earthquake in this region (South-Central Turkey, Jordan, Syria, Lebanon).'