The omicron coronavirus variant is spreading at an unprecedented rate and current Covid-19 vaccines may be less effective at preventing infection, transmission, severe disease and death, the World Health Organization (WHO) has warned.

       The omicron variant, first detected in South Africa and Hong Kong last month, has now been reported by 77 countries and is probably present in most nations, WHO Director-General Tedros Adhanom Ghebreyesus said late on Tuesday.

       "Omicron is spreading at a rate we have not seen with any previous variant," Tedros told an online briefing. "Even if omicron does cause less severe disease, the sheer number of cases could once again overwhelm unprepared health systems."

       "Evolving evidence suggests a small decline in the effectiveness of vaccines against severe disease and death, and a decline in preventing mild disease or infection," he said without giving specifics.

       Pfizer-BioNTech’s Covid-19 vaccine has been less effective in South Africa at keeping people infected with the virus out of hospital since the omicron variant emerged last month, a real-world study published on Tuesday showed.

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       And preliminary evidence indicates that vaccines may be less effective against infection and transmission linked to omicron, which also carries a higher risk of reinfection, the WHO said on Wednesday.

       The WHO, in its weekly epidemiological update, said that more data was needed to better understand the extent to which omicron may evade immunity derived from either vaccines or previous infection.

       Nevertheless, Mike Ryan, WHO’s emergencies director, said that vaccines are not failing and still do provide significant protection against severe disease and death.

       "The question is how much protection are the current vaccines that we are using, which are currently life-saving against all the variants, and to what extent do we lose any protection against severe illness and death against omicron. The data is pointing towards there being significant protection."

       Ryan said the peak of this wave of infections remains "a number of weeks" away given the very rapid spread of the omicron variant, which has outpaced the dominant global strain delta.

       The WHO noted that the emergence of omicron had prompted some countries to roll out Covid-19 booster programmes for their entire adult populations, even while researchers lack evidence for the efficacy of boosters against this variant.

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       “WHO is concerned that such programmes will repeat the vaccine hoarding we saw this year, and exacerbate inequity," Tedros said.

       Reuters