TWENTY-SIX patients, including two pregnant women, are fighting for their lives in hospital intensive-care units around the country after contracting swine flu.
It is now feared that the numbers who are suffering from swine flu could double in the coming weeks.
The seriously ill patients -- whose ability to fight the virus was reduced because of underlying health conditions -- including long-term illnesses, are being monitored for further complications.
Health officials have reported that the number of people struck down with flu doubled in the past week and the number of hospitalisations trebled.
Around 5,400 people have now been treated by GPs for flu-like illness and the spread of the viruses is expected to continue to rise -- particularly next week as children return to school.
Most of those diagnosed with the illness so far this year are suffering from swine flu but other seasonal strains are also circulating and posing a threat to people who have not been vaccinated.
The rate at which people sought treatment for flu-like illness rose to 120.6 per 100,000 population up to last Sunday, up from 59.5 per 100,000 the previous week.
While it is still far off the swine flu high of 200 per 100,000 last year, Chief Medical Officer Dr Tony Holohan warned yesterday that last winter's peak could yet be surpassed.
The rates are expected to rise for two to four weeks before levelling off but officials had "expected and planned" for this kind of surge, he added.
Since October, 114 people have been hospitalised with flu and 33 have ended up in intensive care. Most had swine flu but a significant number were infected with influenza A and B. Twenty-nine were pregnant or had recently given birth.
Twenty went to hospital emergency departments after developing symptoms, but the majority were seen by GPs.
No deaths have been reported this winter from swine flu, which claimed the lives of 27 people last year.
Dr Holohan said there was plenty of flu vaccine available and at-risk groups should avail of the jab. Around one third of the population are immune to swine flu, either because they became ill with the virus last year or have been vaccinated.
Dr Darina O'Flanagan of the Health Protection Surveillance Centre said that unlike last year when children under five years were the worst affected, the highest number of cases currently has been seen in the 15-64 age group.
Those who received the swine-flu vaccine last year would still have immunity but at-risk groups should get this year's seasonal jab because it also protects against the other strains that are circulating.
Dr Kevin Kelleher, head of health protection in the Health Service Executive, said there were around one million doses of antiviral medicines in stock to treat people who have developed symptoms and to stop the illness getting worse.
People who develop symptoms should rest in their rooms and try to isolate themselves from others in the household. They could self-medicate with fluids and paracetamol.
However, those in at-risk groups who develop symptoms should ring their GP and if anyone has a flu which is getting worse they should also seek urgent medical attention.
The Department of Education is to reissue schools with last year's advice and guidelines on how to reduce the risk of swine flu and how to respond if there is an outbreak.