Northern Ireland's chief scientific adviser, Professor Ian Young, has warned that as many as one in 40 people may have Covid-19 in some areas there.
He said one in 100 people there have had a Covid-19 diagnosis in the last week, but said that this 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.
An additional 17 deaths with Covid-19 have been reported in Northern Ireland, the Department of Health said.
Another 1,410 people have tested positive.
Hospital occupancy across Northern Ireland was put at 103%.
There are a total of 599 Covid-confirmed inpatients, 44 of whom are being treated in intensive care.
It comes amid stricter lockdown measures, including a legally enforceable stay-at-home order, that have been agreed by Stormont ministers to stop a rise in transmission of coronavirus.
Ministers agreed earlier this week to give police the power to enforce the stay-at-home order, taking effect from Friday.
First Minister Arlene Foster said the R rate of spread of the virus was towards the upper end of that predicted, nearing 1.8.
She repeated that the last two weeks of January could see a peak in hospital admissions.
"It is a very concerning time and we will need to get through this."
No public worship until next month
Public worship in Northern Ireland will cease until February due to the high level of Covid-19.
The Church of Ireland, the Presbyterian Church in Ireland and the Catholic Bishops of Northern Ireland have issued statements this evening urging people to stay at home.
The decision comes following a briefing today with Northern Ireland's Chief Medical Officer and its Chief Scientific Officer in consultation with the Executive Office.
The faith leaders have expressed support for the message from the public health authorities that the movement and gathering of people should be minimised.
Gatherings for worship will cease from midnight tonight until Saturday, 6 February.
The Methodist Church in Ireland and other denominations and faith communities have also called on people to stay at home.
Meanwhile, GCSE, AS and A-level schools examinations, which are due to take place later this month, next month and in May and June, have been cancelled in Northern Ireland due to the pandemic.
No information is available on the alternative awarding arrangements that will replace the exams system.
Additional reporting Ailbhe Conneely