The largest number of positive flu cases this season have been detected in children and young adults, according to the latest statistics from the National Disease Surveillance Centre.
Of the 47 cases confirmed since October, 33 cases were found in people under 34 years of age. Some 13 cases were found in people aged between 25 and 64.
While older people are in the high risk group for contracting the virus, only one positive case of flu has been reported in an over 65-year-old since last month. This could be attributed to the stronger uptake of the flu vaccine by the older age group.
The largest number of positive flu cases have been found in the Eastern Region Health Authority area (22), followed by the South Eastern Health Board area (8) and the Mid Western Health Board region (6).
Last week, the North Western Health Board and the Western Health Board were the only regions to report no flu activity.
The week saw a dramatic rise in the number of flu-like illnesses reported by GPs who record the information for the National Disease Surveillance Centre.
Almost 68 people per 100,000 of the population reported with such illnesses last week, compared with under 30 people in the previous week.
Meanwhile, the Irish Medical Organisation has urged people not to panic about reports of lethal flu viruses.
Dr James Reilly, chairman of the IMO's GP committee, said he would not like to think that the extent of the virus was being hyped up. "We need to be always alert to the dangers of any new virus but I think that people should not be panicked into believing that every runny nose and cough means they have this very serious illness," he said.
Thousands of viruses were in the air, Dr Reilly said, and people often believed they had influenza when it was something much milder.
"People should be alert and informed but not panicked or over-alarmed," he said. "However, it is a timely reminder for high risk groups to avail of the flu vaccine if they have not already done so."
High risk groups include over 65-year-olds, people with chronic heart conditions, chronic respiratory disease, diabetes mellitus and those who are immuno-suppressed.
