Omicron spreads faster, reduces vaccine efficacy: WHO

United States, Dec 12: The Omicron coronavirus variant appears to be more transmissible than the Delta variant and early evidence suggests it causes a "reduction in vaccine efficacy against infection and transmission," the WHO said in a technical brief.

"Given the current available data, it is likely that Omicron will outpace the Delta variant where community transmission occurs," AFP quoted WHO as saying.

The WHO said Omicron had spread to 63 countries as of December 9. Faster transmission was noted in South Africa, where Delta is less prevalent, and in Britain, where Delta is the dominant strain.

The world heald body stressed that a lack of data meant it could not say if Omicron's rate of transmission was because it was less prone to immune responses, higher transmissibility or a combination of both.

Omicron infections have so far caused "mild" illness or asymptomatic cases, but the WHO said the data was insufficient to establish the variant's clinical severity.

The first omicron case was reported from South Africa on November 24. Vaccine manufacturers Pfizer/BioNTech last week said three doses of their jabs were still effective against Omicron.