Boris Johnson is “responding to treatment” for his coronavirus symptoms, Downing Street has said.

The prime minister has now spent two nights in intensive care in St Thomas’ Hospital in London.

Providing an update on his condition on Wednesday afternoon, the PM’s spokesperson said: “The prime minister remains clinically stable and is responding to treatment.

“He continues to be cared for in the intensive care unit at St Thomas’ Hospital.”

The spokesperson added that Johnson remained “in good spirits” and was “receiving standard oxygen treatment and is breathing without any other assistance”.

Foreign secretary Dominic Raab, who is standing in for the PM where necessary, yesterday said he was “confident” Johnson would pull through and that the prime minister was a “fighter”.

Downing Street confirmed today Johnson is no longer working and Raab had been deputising for the PM since Monday evening.

The spokesman refused to comment on claims in The Times that Johnson’s high temperature had gone down.

“You know my view on anonymous sources who speculate on the condition of people in intensive care,” he said.

Johnson’s top aide Dominic Cummings, who has been self isolating with coronavirus symptoms, “has been in contact with No.10 but he’s not working inside the building”.

Asked whether Larry, the Downing Street cat, was being kept indoors after the British Veterinary Association said felines from self isolating households should not be allowed outside as a precaution, the spokesperson said: “Larry is absolutely fine, I’ve seen him myself this morning, he’s going about his business in the usual way.”

Meanwhile, the spokesperson confirmed that the current lockdown will be reviewed by the government “on or around” the three-week deadline on Monday. It is widely expected to be extended.

“We set out that we would make further announcements in three weeks and there is no change to that,” the spokesperson said. “There is no change at all to the timeline.”

At the same time, he said the chief scientific adviser, Sir Patrick Vallance, and the chief medical officer for England, Professor Chris Whitty, had both made it clear that it was too early to say when the coronavirus pandemic would reach its peak and it would be safe to ease the restrictions.

It came as former health secretary Jeremy Hunt said it would be “reasonable” to assume the lockdown will be extended for another month, taking it into the middle of May.

Hunt, who chairs the Commons health committee, told BBC Radio 4′s World At One: “When you have a lockdown you would expect the impact of that lockdown to feed its way through into the levels of hospital admissions after about two weeks.

“But as we have seen from Italy and other countries you don’t get a peak and then an immediate reduction, you stay at that peak level for some time, and of course it’s at different points in different parts of the country.”

Hunt added: “It seems to me you hit the peak, perhaps at the beginning of next week, then you have two to three more weeks before you start to see the numbers really decisively turning.

Asked if lockdown could continue for another month, Hunt said: “I think that’s a reasonable assumption as someone from the outside who’s not seen on a daily basis the scientific recommendations, I think that’s reasonable to assume.”

The second NHS Nightingale Hospital, which has been built at the National Exhibition Centre in Birmingham, will open on Friday with 500 beds to treat coronavirus patients, with the capacity to expand to 2,000, No.10 also confirmed.

The third Nightingale hospital is expected to be opened in Manchester in the next week, the spokesman added.