Coronavirus lockdown restrictions may be lifted earlier in Northern Ireland than in the rest of the UK, the first minister, Arlene Foster, has said, as it emerged that extra critical care capacity is not expected to be needed during the first wave of the pandemic.

The death rate in Northern Ireland is half that of England, and the projected death toll from coronavirus in Northern Ireland was revised down this week to 1,500. Earlier modelling had suggested a worst-case scenario of 15,000 deaths.

The health minster, Robin Swann, said on Thursday: “For the time being our latest data modelling indicates that further critical care capacity will not be required during the first wave of transmission in Northern Ireland.”

A virologist at Queen’s University Belfast has put the lower than expected death toll down to Northern Ireland’s low population density compared with other parts of the UK.

There have been 263 deaths in Northern Ireland to date, a rate of 14 deaths per 100,000 population, compared with England’s 30 deaths per 100,000, based on the latest daily figures on hospital deaths published by NHS England.

The three smaller UK nations all recorded their first deaths later than England, which may mean the disease began circulating later, while less urbanisation in Scotland, Wales and Northern Ireland could also be a contributory factor.

But Swann warned against complacency in any moves to ease the clampdown on social, business, travel and other activities over the next few weeks.

Foster said lockdown measures would be eased when scientific and public health criteria were met and she would give no timetables or dates.

Foster told Cool FM radio on Thursday that any lifting of the lockdown would have to be “set down and agreed” with both the power-sharing Northern Ireland executive and the government in London.

“And because of that, you could well see different parts of the United Kingdom move in different time to other parts, because it will be criteria-led,” she said. “What do I mean by that? We will have to look at the amount of admissions to hospital, the admissions to intensive care units, the number of deaths we have, what it means for us in terms of the science.”

Northern Ireland’s chief medical officer, Dr Michael McBride, said local health officials had recorded a flattening of the Covid-19 infection curve in the region.

Dr Lindsay Broadbent, a virologist and research fellow at the Wellcome/Wolfson Institute for Experimental Medicine at Queen’s University of Belfast, said there were some grounds for optimism that aspects of the local lockdown could be lifted.

“There may be regional differences to ending the lockdown across the UK and Ireland. This will have to be guided by the science,” she told the Guardian.

Broadbent said Northern Ireland’s lower projected death toll from the coronavirus was “due to population density and hospital and ICU capacity, for example”. Another factor was that “stricter measures may have been in place longer than somewhere like London.” All of Northern Ireland has been in lockdown since 17 March.

Swann, appeared more sceptical about lifting restrictions compared with the first minister. He said it was too early for his department to confirm that the number of Covid-19 deaths had peaked in the region.

“While there are grounds for hope that the outbreak can be brought under control, the outbreak has not reached a point where some of the measures can be relaxed,” he said.

One of the most controversial measures of Northern Ireland’s lockdown has been the closure of all cemeteries. Members of the public unable to visit loved ones’ graves have complained that while cemetery gates are locked, large queues snake outside off-licences, which remain open.

The Northern Ireland executive remains split over cemetery closures, with Sinn Féin in favour of keeping them closed while the Ulster Unionists have argued they could be reopened with strict distancing measures.