The Health Protection Surveillance Centre says the rate of influenza-like illness in the country is the highest seen since the winter of 2000-2001.

During the first week of January, more than 100 people out of every 100,000 have been diagnosed with influenza or an influenza-like illness, according to the latest figures.

The agency is urging people in high-risk categories, such as those over 65 and children with chronic conditions, to get vaccinated.