Swine flu is this year's big threat to vulnerable
Young people and pregnant women could be among the worst hit by this year's flu season as swine flu is likely to be a dominant strain.
The forecast warning of swine flu, the AH1N1 virus, was made at the recent meeting of the emergency department task force.
HSE public health specialist Dr Kevin Kelleher said if the pattern is the same here this winter as the Australian flu season, it will be this strain that will dominate.
The age profile of those who fall ill will be younger and there tends to be a slight increase in pregnant women when it predominates, he added.
There will be more pressure seen in hospital intensive care units.
But there are usually lower rates in older people, and the number of outbreaks tends to be lower that when another strain of the virus is mostly circulating.
However, he cautioned that there could be a pool of susceptible individuals, particularly children under the age of four, who could pass it on to the elderly.
Dr Kelleher stressed that predicting how the flu season will turn out is difficult.
So far this winter the swine flu is dominant which could mean the scenario outlined will mark this year's season.
However, there is a low level of flu circulating at this stage, and a relatively small number of cases.
Currently the ratio of swine flu to the B virus is around 60:40.
One of the plus sides of the swine flu dominating the winter is that it is better covered by the seasonal flu vaccine.
Flu rates traditionally spiral around the end of December and early January as more people travel and also congregate in homes and social gatherings, increasing the risk of spread.
It contributes to the rush of patients attending A&E departments, fuelling the trolley crisis.
Last winter brought a prolonged flu season with a higher percentage of the B strain of virus.
It has a high impact on the elderly who were hospitalised in large numbers and also admitted to intensive care units.
The outbreaks of flu in nursing homes were the highest ever recorded.
There were excess deaths for 11 weeks.
Overall there were 255 notified flu deaths last winter, the highest ever reported, according to a report.
The median age of those who died was 81 years.
Six deaths were recorded in those aged less than 18 years of age, four associated with influenza B and two with influenza A.
The median age of hospitalised flu cases during the season was 63 years.
Of the 200 notified flu outbreaks reported where one person passes the infection on to another the majority were in residential care facilities such as nursing homes and other centres.
Others happened in hospitals.
The trolley crisis brought record levels of overcrowding last year which increased the risk of one patient passing on the flu to another.
The advice to at-risk groups is to get the flu vaccine which will offer some protection.