Published Thursday, 20 January 2011
The Public Health Agency said 18 had underlying medical conditions, two did not and one case is still unclear.
In the latest flu bulletin published on Thursday, the PHA said that there were 85 new laboratory confirmed cases of swine flu in Northern Ireland last week compared to 219 in the first week of January 2011.
It said the main markers of the level of flu, including new cases and GP consultation rates, have "all decreased significantly in the past week."
Dr Carolyn Harper, Director of Public Health for Northern Ireland, said: "It is reassuring that the number of new flu cases per week has more than halved. If the current trend continues, the peak of this year's flu season has passed."
She said vaccination still remains the most effective way to "protect those who are most at risk from flu and its complications."
At a briefing on Thursday John Compton, Chief Executive, Health and Social Care Board, outlined the impact of flu and seasonal winter pressures on the health and social care services.
He said that as of Wednesday 18 out of 76 adult critical care patients and one out of eight paediatric critical care patients were being treated for flu.
"Of all patients being treated in hospital in Northern Ireland today, approximately 1.66% have been confirmed with swine flu or are suspected as having it", he added.
"This is not unusual at this time of year when flu is most prevalent."
Elective surgery was postponed for 138 people in the last week to meet the demands of swine flu sufferers.
Patients affected by the delay will be contacted directly by their hospital.
© UTV News