Governments around the world are urgently scouring databases for recent cases of COVID-19 infections, screening travelers and decoding the viral genomes of the new variant as they try to measure how far it has spread.
The pace of the work highlights the pressure on governments and public health authorities to decide quickly whether they need to take unpopular, economically damaging steps to curb omicron's spread.
Data shows it was circulating before it was officially identified in southern Africa last week and it has since been detected in more than a dozen countries. Work to establish if it is more infectious, deadly or evades vaccines will take weeks.