Isolation may be reduced from seven days down to five, but only if it is recommended by health experts.
If approved, the rule change would only apply to those who are fully vaccinated against Covid-19.
Those who are unvaccinated would still be required to self-isolate for 10 full days.
Speaking during a visit to a vaccination clinic in Uxbridge, the Prime Minister said: “There’s a similar argument to be had about the quarantine period – whether to come down from seven days to five days.
“The thing to do is to look at the science. We are looking at that and we will act according to the science.”
Ministers are currently under pressure to ease restrictions and reduce the isolation time for positive cases down to five days, in line with the United States.
The Centre for Disease Control (CDC) in the US recently cut the isolation requirement from 10 days to five, providing people are not showing symptoms and masks continue to be worn for a further five days.
Chancellor Rishi Sunak is reportedly among the ministers keen on reducing the quarantine period from seven to five days due to the economic benefits, according to the Daily Telegraph, while Education Secretary Nahim Zahawi has suggested the move could help to ease coronavirus-related staff shortages.
He said the decision will be investigated by the UK Health Security Agency, telling Sky’s Trevor Phillips on Sunday: “It would certainly help mitigate some of the pressures on schools, on critical workforce and others.
“But I would absolutely be driven by advice from the experts, the scientists, on whether we should move to five days from seven days.
“What you don’t want is to create the wrong outcome by higher levels of infection.”
PM to set out ‘living with Covid plan’
Boris Johnson is expected to set out a plan for how the UK can live with Covid-19 and what measures will be needed in the months ahead.
The PM is understood to be drawing up a ‘living with Covid’ strategy, which could include reducing self-isolation periods and potentially scrapping free lateral flow tests, although the latter has been denied by Mr Zahawi.
It has yet to be confirmed when Mr Johnson will outline a plan, but it is unlikely to be set out while case rates remain so high and the NHS is facing significant pressure due to staff absences.