Omicron spreads faster and weakens vaccine immunity, says WHO

WHO stresses lack of data means it cannot ascertain reason for variant's fast transmission rate

Children walk through the settlement of Vlakfontein outside Johannesburg in South Africa. Although children under 12 are not taking part in the country's Covid-19 vaccination campaign, cases in young children are on the rise since the discovery of the Omicron variant. AP

People wearing face masks to protect against Covid-19 cross the Concorde square in Paris. The World Health Organisation says early evidence suggests the omicron variant may be spreading faster than the highly transmissible delta variant, but brings with it less severe coronavirus disease. AP

President Joe Biden delivers remarks in the state dinning room at the White House in Washington. The US president and the vice president held a meeting with members of the White House Covid-19 Response Team on the latest developments related to the Omicron variant. EPA

Dr Anthony Fauci, chief medical advisor to President Joe Biden, attends a Covid-19 meeting at the White House. EPA

People wait in line to get tested for Covid-19 in Times Square, New York. AFP

The Omicron variant of Covid-19 has been detected in at least 19 US states. Health officials are urging Americans to get vaccinated and receive their booster shots. AFP

Leonardo Velasco, 4, reacts as he receives a dose of the Sinopharm vaccine in Caracas, Venezuela, Reuters

People wear face masks as they ride a bus after the first case of the Omicron variant was detected in Pakistan. The case was reported in a private hospital in Karachi by a patient with a history of international travel. EPA

A health care worker prepares a dose of the Pfizer vaccine in Johannesburg, South Africa. Reuters

A medical worker holds a sign for visitors to prepare for coronavirus tests at a temporary screening clinic in Seoul, South Korea. AP

A child waits to receive a dose of the Sinofarm vaccine in La Paz, after Bolivian President Luis Arce authorised the vaccination of children between five and 11 years old. AFP

Ice skaters take a selfie on the ice rink at the Natural History Museum in central London. AFP

A health professional points to a Christmas tree made with Covid-19 and flu vaccine vials at the Public Health Basic Unit 'Ernani Agricola' in the Lapa neighborhood in Rio de Janeiro, Brazil. AFP

Skaters, most wearing face masks to combat the spread of coronavirus, skate on the ice rink at the Natural History Museum in London. AFP

A medical worker prepares a Moderna vaccine on the first day of the re-opening of a Covid-19 vaccination centre in Merignac, on the outskirts of Bordeaux, France. AFP

Live updates: follow the latest news on Covid-19 variant Omicron

Early data shows the Omicron coronavirus variant is more transmissible than the Delta strain and reduces vaccine efficacy, but causes less severe symptoms, the World Health Organisation said on Sunday.

The Delta variant, first identified in India this year, is responsible for most of the world's coronavirus infections.

But South Africa's discovery of Omicron, which has a large number of mutations, last month prompted countries around the world to impose travel bans on southern African countries and reintroduce domestic restrictions to slow its spread.

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.

But the WHO 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.

Early evidence suggests Omicron causes "a reduction in vaccine efficacy against infection and transmission", the agency said in a technical brief.

"Given the current available data, it is likely that Omicron will outpace the Delta variant where community transmission occurs," it said.

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.

South Africa reported Omicron to the WHO on November 24.

Vaccine makers Pfizer and BioNTech last week said three doses of their inoculations were still effective against Omicron.

Countries with sufficient vaccine supplies, such as Britain and France, have encouraged their populations to receive a third "booster" shot to fight Omicron.