Up to 53,000 Irish people could be killed if a severe flu pandemic were to strike now, according to estimates from the national group which has been planning for the eventuality.
The group, which published its plan yesterday, estimated that in "a worst case scenario" the pandemic could result in two million people in the Republic becoming infected, 78,000 people being hospitalised and around 53,000 deaths.
If the pandemic was less severe, the group estimates that one million Irish people would be infected, around 6,000 people could be hospitalised and 4,000 deaths could occur.
The figures are modelled on what happened during previous pandemics and do not take into account the fact that antivirals are now available and have been stockpiled to treat 40 per cent of the population.
Prof Bill Hall, chairman of the expert group which drew up the plan, said he believes the number of deaths will not reach 53,000 because of the availability of antivirals.
Experts agree that another flu pandemic is inevitable but say it is difficult to predict when it will occur. Prof Hall said it could happen "next week".
The World Health Organisation has advised countries, particularly since the most recent outbreak of the H5N1 strain of avian influenza, to be prepared.
An influenza pandemic can start when a new influenza virus subtype appears, infects humans and spreads easily between humans. The last pandemic was in 1968/1969.
The Health Service Executive, in addition to stockpiling antivirals and the H5N1 vaccine for healthcare workers, is stockpiling 500,000 surgical masks, five million pairs of disposable gloves and 150,000 surgical gowns.
Arrangements for dealing with the burial of the thousands who could die are being worked out.
In the event of a pandemic, public gatherings would be banned, schools would close and people who had symptoms of the virus would be advised to call a telephone hotline for advice and stay at home rather than going to their GP or attending A&E.
The reason for this would be to prevent them infecting others as well as swamping an already burdened system.
The aim would be to get antivirals such as the stockpiled Tamiflu or Relenza to those infected in their homes within 48 hours. It is not clear yet however how these would be delivered. Discussions with the Irish College of General Practitioners and pharmacists are taking place.
The pandemic influenza expert group, in its plan, "advises that it is critical that sufficient attention is given to the significant logistical problems that will arise in achieving timely and appropriate distribution and delivery of antiviral drugs, and that sufficient resources are put into planning a robust capacity to deliver antiviral drugs as needed as quickly as possible".
Gavin Maguire, head of emergency planning with the HSE, said the public would have a huge responsibility in managing a pandemic. It will be essential they listen to the advice issued and act on it. He urged the public to read the national pandemic influenza plan. The plan states that "the evidence at this point does not support a recommendation for public use of face masks as a measure to prevent transmission of disease during a pandemic".
Mr Maguire also said all non-essential services in hospitals, such as elective surgery, would be cancelled or postponed during a pandemic to free up beds and staff to deal with other patients.
Meanwhile, Prof Hall said he had asked the makers of Tamiflu for more information on reports of adverse reactions to the drug.