Covid-19 restrictions are to be extended to all of Northern Ireland from 18:00 BST.
There will be no mixing of households indoors with some exceptions, and no more than six people from two households can meet in a garden.
The move followed an urgent meeting of the Northern Ireland Executive on Monday afternoon.
In the last seven days, more than 1,000 people have tested positive for Covid-19 in Northern Ireland.
First Minister Arlene Foster said “this is not a return to lockdown”, but “doing nothing is not an option”.
She added: “The restrictions are limited and we are in a better place than at the height of the pandemic.”
Mrs Foster told the briefing that Northern Ireland is now dealing with outbreaks in every county and without action there was a real risk of increasing spread.
She said it could lead to increasing hospital admissions and deaths.
Deputy First Minister Michelle O’Neill said the fact that over 1,000 cases were recorded across the island of Ireland at the weekend should act as a “wake-up call to everyone”.
According to the Department of Health dashboard, another 125 new positive cases have been recorded since Sunday.
Thirty-three people are currently in hospital, with five in intensive care.
In the Republic of Ireland 188 new cases of coronavirus were reported in the past 24 hours. No deaths were recorded there.
The Chief Scientific Officer Professor Ian Young said there has been some evidence of a reduction of cases in Ballymena following local restrictions there.
“So we do have some evidence that the measures may be effective and it will take a little longer to see their full effect in other areas,” he said.
He also said Northern Ireland is now averaging well over 100 new cases per day and the percentage of positive tests is also increasing.
He told the briefing, the R rate, which is how quickly the virus spreads, is currently at 1.4 and in some places stands at 2.Prof Young said the level of cases in Northern Ireland is higher than the Republic of Ireland and the rest of the UK,.
But he added we are currently in a lag period between new cases, hospitalisations and deaths which gives the executive an opportunity to intervene.