Experts say older people are particularly vulnerable to the flu and the H3N2 Brisbane 10 flu strain which killed six children in Australia and caused a severe epidemic is spreading within the UK and Ireland, Bulgaria and Spain are also under pressure from the virus - another 11 countries are also affected.
The current flu epidemic is well on the way to being the worst in eight years and experts expected it to peak between January and March.
There has been a sharp increase reported in the number of flu-like illnesses over the past two weeks, with seniors the worst-hit and the health service has been struggling to cope over the Christmas period - among the over-65s, 45 in every 100,000 people now have flu, up from just 18 a week ago - the elderly are the most likely to die from flu.
Doctors surgeries have been closed over the holiday period and sufferers have had to resort to hospital accident and emergency departments for help, many of which were already under increased pressure because of outbreaks of the winter vomiting bug norovirus.
Though it is still the 15 to 44 age group who are reporting the most cases, with a rate of 80 per 100,000, it is the elderly are most likely to die from flu.
This year's outbreak is on course to be the worst since 1999, when 22,000 people died - an outbreak does not become an epidemic until the rate is higher than 200 per 100,000.
Experts say older people often have the most serious consequences with the lungs put under increased pressure and the threat of viral pneumonia and the increased risk of contracting a second bacterial infection - also vulnerable are those with heart problems, diabetes or asthma and those whose are immune systems are compromised.
They say the influenza vaccination programme has been good in some areas but patchy in others but most people with flu would not need to see a doctor and would be fine within two or three days.
The Health Protection Agency advises the public to take up the offer of free flu vaccination at their local surgery and be alert to symptoms which can include a headache, fever, cough, sore throat, and aching muscles and joints and says for most people flu is unpleasant, but not life-threatening.
Flu victims are advised to stay at home, rest, drink plenty of fluids and use over-the-counter remedies to make themselves more comfortable - to avoid passing it on to others hands should be washed regularly, mouths and noses covered when sneezing and used tissues disposed of correctly.
All those over 65 are entitled to the flu vaccine free - around 70% have apparently taken it up - as are others deemed 'at risk' - this includes people with breathing problems or asthma, people with heart problems or high blood pressure, kidney failure, liver disease, diabetes, those who have had a stroke or people on immuno-suppressive drugs.
As well as vaccinating at risk groups doctors are authorised to prescribe drugs called antivirals which combat the symptoms of the disease and can shorten its duration.