Ireland could be facing the deadliest outbreak of flu seen in the country in over 50 years, experts have warned.

The first flu deaths have been recorded in Ireland as the dreaded 'Aussie flu' sweeps the country.

The HSE is urging people in high-risk groups to get the flu vaccine.

Until last week there had been no reported deaths from flu so far this winter. However, the HSE has now confirmed that they have been notified of a a small number of deaths - less than 10 - directly related to flu.

The main strain posing a risk in Ireland is the so-called 'Aussie flu', a virulent strain of influenza A. The H3N2 subtype triggered two-and-a-half times the normal number of cases in Australia.

The elderly who may have compromised immune systems are particularly susceptible.

Cases of swine flu and the B strain have also been detected.

Some experts have warned this could be the most serious flu epidemic since the 1968 pandemic that began in Hong Kong and killed a million globally.

In recent days, GP services in Ireland are being put under massive pressure as a result of the number of infections.

Ireland is facing a rise in those hospitalised with flu, and a number of breakouts in nursing homes.

Emergency doctors in Dublin, Limerick, Donegal and Galway all reported a substantial increase of calls from those suffering flu-like symptoms.

Dublin’s ‘D Doc’ service last night had only a small number of appointments left.

The ‘Aussie flu’ is a mutated strain, meaning the vaccine in Australia has been less effective than anticipated. The HSE has confirmed that the vaccine here should be “a moderate to good match” and encouraged people to get the jab.

However, it will not know the success of the Irish vaccine until flu season is over.

Dr Kevin Kelleher, Director of the HSE’s Health Protection Surveillance Centre said: “Influenza-like illness has increased in all age groups except in those aged 0-4 years. Hospitalised cases of influenza and influenza associated outbreaks in residential care facilities have also increased. The HSE has in the last fortnight also been notified of a small number of deaths directly related to influenza (less than 10).

"These indicators tell us that flu is actively starting to circulate in the community, yet it’s not too late for people at risk to get the vaccine from their GP or Pharmacist. Prevention is better than cure, and the increase in flu activity means it is even more important to get your flu jab if you are in an at-risk group. Initial indications so far point to more people in at risk groups and more healthcare workers getting the flu vaccine this year. The HSE would urge those who have not yet been vaccinated to join their peers and their colleagues in getting the flu vaccine."

The HSE have said that high-risk groups are:

All those aged 65 years and older

People including children with chronic illness requiring regular medical follow-up such as chronic lung disease, chronic heart disease, chronic neurological disorders, neurodevelopmental disorders and diabetes

Those with lower immunity due to disease or treatment and all cancer patients

All pregnant women. The vaccine can be given safely at any stage of pregnancy.

Those with morbid obesity i.e. Body Mass Index ≥ 40

Residents of nursing homes, old people's homes and other long stay facilities

Health care workers and carer’s of those in risk groups.

“People in ‘at risk’ groups can get the flu vaccine itself free of charge (people without medical or GP visit cards may be charged an administration fee). This is because they are at much greater risk of becoming seriously unwell if they catch flu, and may need specific treatment or hospital care," Dr Kelleher added.

It comes as the HSE's latest weekly influenza surveillance report, for the week ending December 17, recorded an increase in influenza activity.

Flu cases have led to 73 hospitalisations so far this winter, 19 of which occurred last week. It has now been confirmed for the first time that lives have been lost.

"There are deaths every year that happen directly as a result of the flu," Dr Kelleher said "which account for about 18 to 20 fatalities. On average, there are about 400 to 600 deaths a year which are associated with the flu indirectly.

"For example, these are people who may have died because of the heart disease, linked to the flu."

He warned influenza B particularly affects those aged between five and 14.

Flu scientists are predicting that 2017's outbreak could be one of the worst in half a century. This is based on the recent epidemic in Australia - our flu season follows theirs - where there were twice as many cases and deaths as the year before.

Dr Kelleher stressed it was not too late for people to be vaccinated. The more people who get it, he said, the less likely there will be a serious flu problem in the country.

"The most important thing is that if people think they've got it is to stay at home and look after themselves.

"The vast majority of people - 99pc of cases - can look after themselves at home."

The HSE's Health Protection Surveillance Centre (HPSC) has urged people in high-risk groups to get the flu vaccine. Those over 65, pregnant women and those under 65 with various health conditions are particularly at risk.

The flu virus indirectly resulted in the death of 1,000 people in Ireland last season.There are three main types of flu virus - A, B and C - and hundreds of different subtypes.

The A virus has caused some of the worst outbreaks in history, including the infamous Spanish flu in 1918 and swine flu in 2009. It mutates about three times faster than B, making it more likely that a new strain of A will cause a pandemic.

Australia - whose winter occurs during the Irish summer - had one of its worst outbreaks on record, with two-and-a-half times the normal number of cases.

Some of the Australia's A&E units had 'standing-room only' after being swamped by more than 100,000 cases of the H3N2 strain.

D-Doc, North Dublin's out-of-hours GP service, has temporarily suspended its phone lines due to a high number of calls.

The service said that all appointments were filled and that patients in need of emergency care should go to their local A&E departments.

Online Editors