A record 1.7 million people in the UK tested positive for Covid in the past week, data released on Christmas Eve showed - plunging most of them into isolation on Christmas Day.
The number, for the week ending December 19, is the highest weekly number recorded, said the ONS. London was the epicentre of cases, with around one in 20 testing positive, the highest of any region.
The survey found that one in 35 people in England were likely to have had Covid that week, up from one in 45 people the previous week.
Prime Minister Boris Johnson urged all adults to get their booster jab as ministers bank on the campaign to ward off the impact of the Omicron wave.
A study released by the UK Health Security Agency on Thursday evening suggested Omicron cases in the UK have a lower risk of hospitalisation than Delta cases.
But ministers warn that its sheer transmissibility could still overwhelm the NHS. New restrictions have been ruled out before Christmas Day on Saturday, but have not been ruled out before the New Year.
