Eleven people in Northern Ireland have now died from flu, the Public Health Agency has said.
Officials also recorded 64 flu-related admissions to intensive care.
The figures come as thousands across the UK have been hospitalised by flu, with four strains of the killer virus identified, including the 'Aussie' and 'Japanese' strains.
Japanese flu is believed to be responsible for nearly half the hospitalisations recorded, while the dreaded H3N2 strain that rocked Australia caused a sixth of them.
New data shows that the number of flu cases being presented in the first three weeks of 2018 in Northern Ireland was double the number from last year, but figures are now said to be declining.
A PHA spokeswoman said that while "flu activity decreased last week", it still "remains at moderate levels".
"Flu can be a serious disease every year, however, to date, the current flu viruses circulating are not causing more serious disease than in previous years," she said.
"Up to January 21, there have been 64 cases of flu requiring admission to the intensive care unit, and a total of 11 deaths in ICU with confirmed influenza."
Seasonal flu activity in Northern Ireland is monitored throughout the year to inform public health action and to prevent spread of the infection.
Dr Lucy Jessop, a consultant at the PHA, called for caution, adding: "People are still falling ill with flu, so we should all take steps to prevent its spread".