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All options are on the table to tackle coronavirus, Northern Ireland's health minister has said.
In a lengthy statement, Mr Swann writes that a social distancing strategy will need to take place over months, rather than weeks.
He added the coronavirus outbreak may be "the greatest societal challenge since the Second World War".
His remarks come amid calls from some politicians for further steps - including closing NI's schools.
But he said closing schools at this stage could be "counterproductive".
Special schools in Belfast have announced they will close indefinitely from Monday.
The Irish government has called on pubs to close as part of containment measures, coming into effect on Sunday and lasting until 29 March, while all schools and colleges in the Republic of Ireland are shut.
Questions are being asked about the number of ventilators available in Northern Ireland.
Ventilators are vital in the treatment of patients whose lungs have been attacked by the infection.
Dr Chris Hagan, interim medical director at the Belfast Trust who is overseeing the Mater's response to the outbreak, told BBC Radio Ulster's Good Morning Ulster programme "what scares us is the potential for the numbers of patients that could come".
"We have been preparing for the worst but I am confident we are prepared for that and confident our staff will rise to that challenge," he said.
"All of our patients so far have gone home well. We haven't had to ventilate any patients with Covid-19 yet, but I am sure that will come."
UK Prime Minister Boris Johnson is due to speak to engineering firms on Monday about whether they can shift production lines to building NHS ventilators.
School closures
First Minister Arlene Foster said on Saturday school closures would be introduced when "medical evidence" advised it was necessary but they could last up to 16 weeks.
Deputy First Minister Michelle O'Neill has repeatedly called for schools in Northern Ireland to close immediately.
SDLP leader Colum Eastwood and Archibishop Eamon Martin, the leader of the Catholic Church in Ireland, also said schools should shut now.
Eleven new cases of coronavirus were confirmed in Northern Ireland on Sunday, bringing the total to 45.
Mr Swann said people "want to know that concrete action is being taken".
"Let me make clear that all options are on the table when it comes to protecting our citizens," he said.
"That includes all the social distancing measures that will work but which must also be sustained for long enough to be effective."
Mr Swann said action would be "guided by evidence of what works" and could when necessary "including school closures".
"If it was just a question of shutting everything down for a limited period, then we would have already done it," he said.
"Closing schools by itself will not be effective, if we can't sustain it. It might even be counterproductive at this stage.
"What is needed is a wider and phased social distancing strategy that holds together and works over months not weeks."
He added that social distancing for older people would be "an important phase" and was about "shielding rather than total isolation".
An attempt to mend some damage
Analysis by Marie-Louise Connolly, BBC News NI health correspondent
This is not a time for ambiguity from governments.
But considering what has unfolded over the past couple of days that is what has happened and which has led to confusion, doubt and criticism across the airwaves and especially on social media.
The next couple of weeks are critical to try to manage the effects of the virus.
And Robin Swann in this statement is trying desperately to address that and perhaps even mend a lot of the damage.
The problem is the public witnessed the executive's cohesion falling apart last Thursday.
Things have been said and a number of schools, businesses and health organisations have announced their own steps perhaps feeling others were not doing it for them.
Robin Swann's statement is an attempt to calm the troops.
The problem is will people listen and feel they are being led by one executive?
BBC News NI understands the Department of Education plans to issue updated coronavirus guidance to schools on Monday.
Education Minister Peter Weir said on Sunday he would continue to be guided "by the science and professional health advice".
Meanwhile, Health Secretary Matt Hancock revealed on Sunday every Briton over the age of 70 would be told "within the coming weeks" to stay at home for an extended period to protect themselves.