The Covid self-isolation period could be cut from seven to five days if scientists give the change the green light.
Boris Johnson has said he will act “according to the science” over reducing the time people have to stay at home if they test positive.
Ministers believe a two-day cut could help ease staffing crises in the public services and other workplaces across the country.
Chancellor Rishi Sunak is among those in the Cabinet keen on the economic benefits of the change, which would bring the UK into line with the United States.
It came as the UK Health and Security Agency admitted it had misread US guidance to argue their five-day period started “some days” later than the British seven-day rule.
Asked about the issue on a visit to a vaccine clinic, Mr Johnson said: “The thing to do is to look at the science. We are looking at that and we will act according to the science.”
No 10 said it wanted to reduce the isolation period “soon” but scientists have yet to assess whether it was safe for people to return to work if they tested negative after five days.
Mr Johnson also pledged that free lateral flow tests would be available for “as long as it is necessary” as ministers considered how to move to a position of living with Covid.
The PM said testing was an important line of defence, along with vaccinations, in the face of the Omicron wave.
Mr Johnson is under pressure from Tory MPs to commit to ending restrictions and shift to a position where Covid is treated in a similar way to other illnesses.
Former chief whip Mark Harper, an influential lockdown-sceptic within the Tory party, urged the PM to declare an end to coronavirus restrictions.
Mr Harper warned the PM he could suffer an even greater rebellion than when he introduced his Plan B measures if he tries to extend them later this month.
The PM, however, was understood to be unlikely to set out further plans while cases rates remain so high and the NHS strains under significant pressures.
A No 10 source told the Mirror it was “too early” to be focusing on anything other than supporting the health service.
UK cases were down on the previous week for the fifth day but changes to testing rules mean from today people no longer need a confirmatory PCR if they test positive.
But a total of 17,120 people were in hospital in England with Covid as of today – a rise of 20% from a week before.
