In total, 1,570 new cases of influenza were confirmed last week (April 11-17) across the country, data from the Health Board shows.
While the number of cases increased by 27 percent, the growth rate has slowed, the agency said.
The virus is spreading fastest amongst those aged between 70-79 and 0-4. Of those newly infected, 48 percent are children.
Hospitalizations rose by 13 percent and almost 50 percent of patients receiving treatment are children. It is expected that there will soon be a rise in the number of elderly patients in hospitals.
Since the beginning of flu season, 195 people have been treated in hospital for severe influenza or influenza-related pneumonia. Three people over 70 have died and none were vaccinated.
So far, 9,965 cases have been confirmed by laboratories.
Editor: Helen Wright