Hospital admissions for coronavirus have increased by almost 50% in some parts of the country amid a pattern of “regional differences” in the spread of Covid-19, the government has said.

Speaking at the daily Downing Street press conference on the coronavirus outbreak, cabinet secretary Michael Gove said the rate of admissions in the Midlands had increased by 47% between 1 and 2 April, while rates in the Yorkshire and the North East had risen by 35%.

London had seen a slight drop in the rate of admissions, while the rate in Wales remained “steady”, he added.

It comes as the total number of recorded coronavirus deaths in UK hospitals rose by 708 to 4,313 as of 5pm on Friday – the steepest rise since the outbreak began.

Stephen Powis, England’s chief medical director, said it “was not unexpected” to see geographic variations in the spread of a the epidemic.

“I think it’s difficult to give an explanation as to why any particular part of country has a higher rate at any one time. I would say that, not unsurprisingly, London, as a major urban centre, has an infection rate that is a week or so ahead of the rest of the country.

“If you look at the normal winter and look at the spread of flu in a normal winter, it’s not unusual to see flu rates in the winter pop up in one area of the country before they rise up in other areas of the country.”

The news follows reports on Friday that hospitals in the West Midlands could reach maximum capacity by next weekend, with the region’s mayor Andy Street saying it was set to become the UK’s next hotspot.

Gove would not be drawn on the government’s “exit strategy” for the crisis, stating that “there’s no fixed point, no specific date in the calendar at which we can say things will change, we are keeping them under review”. Boris Johnson is set to review the lockdown measures currently in place on 13 April.

Earlier on Saturday the government’s key adviser, Prof Graham Medley, warned that a prolonged lockdown risked causing more harm than good and that Britain had “painted itself into a wall” with no clear exit strategy.

During the briefing, Powis said: “I don’t like the term exit strategy. It is very likely that this virus will become established in populations throughout the world and so we need a strategy to manage this over time, not just in the next few weeks or the next few months.” He said the current strategy was to “save lives and protect the NHS”.

Gove thanked China for sending 300 ventilators to the UK, and said hundreds more were being manufactured in the UK every day.

A team from University College London working with Mercedes-Benz has produced a new non-invasive respirator that has been clinically approved. Gove said the machines would be vital in reducing the number of patients who would eventually need to be intubated.

“They produced 250 yesterday, they will produce the same number today and tomorrow, rising to 1,000 a day next week,” he said.

“We are also increasing the capacity of the NHS to deploy invasive ventilation. We have been buying invasive ventilators from partners abroad including Germany and Switzerland. And today 300 new ventilators arrived from China.”