Chief Scientific Adviser Professor Ian Young has warned that as many as one in 40 people may have coronavirus in some parts of the north.
He said one in 100 people have had a Covid diagnosis in the last week, but he said that is an under representation of the true number of cases because many are asymptomatic and are not diagnosed.
"It's very likely that in parts of Northern Ireland there are as many as one person in 40 who currently has Covid," he told the BBC.
He said the Mid Ulster council area has had the highest number of cases in the last week followed by the Armagh, Banbridge, Craigavon area.
Prof Young also warned that with the recent doubling in case numbers, the number of hospital patients with the virus could reach 1,000 in the coming weeks.
"In the past we have had up to around 500 of hospital inpatients being treated for Covid, we could easily before the end of this month rise to 1,000 or more, and indeed depending on the impact of the new variant those numbers could rise even further beyond that," he said.
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He urged the public to listen to the stay at home message as new lockdown measures are set to become law on Friday.
"My message to everyone in Northern Ireland is to please, please listen to the stay at home message which we are trying to give," he said.
"People should only be leaving their home for essential purposes, if they really need to. We all need to minimise our contacts."
The Stormont Executive had been due to meet today but that meeting was postponed until tomorrow following family bereavements affecting two ministers.
However, Health Minister Robin Swann said today that confusion around the rules concerning outdoor gatherings will be "tidied up" later.
Meanwhile. the Belfast health trust hsa announced the cancellation of all planned inpatient surgery this week due to rising numbers of Covid cases.
The Northern Trust said it has cancelled the majority of its planned surgery to both free up staff to support the significant Covid-19 surge.
The South Eastern Trust is still carrying out some elective surgeries, but indicated fewer will be carried out from next Monday due to Covid numbers. Read more
