Tallaght Hospital has asked all staff who are pregnant, severely obese, and those with chronic conditions or HIV to make this known to the occupational health department in case of a swine flu outbreak.
In a memo to managers, seen by RTÉ News, the hospital says the response to a previous request for this information last month was poor.
The hospital says it needs to identify staff that have an increased risk of severe influenza complications if they become infected with the H1N1 virus.
The memo says the hospital wants to undertake a risk assessment.
Hospital CEO Michael Lyons told RTÉ News it had a duty of care to employees and to ensure that there is a sufficient number of staff available to care for patients.
Among the other conditions highlighted are asthma, diabetes, significant heart disease, liver disease and people with neurological conditions.
Separately, a soldier from Northern Ireland died after contracting swine flu.
Bombardier Lee Porter, from Coleraine, Co Derry, died in a hospital in England last week, two weeks after contracting the virus. He had underlying health problems.
The 30-year-old, who was serving with the Royal Artillery, is thought to be the first UK serviceman to have died from the H1N1 virus.
He is the 28th person known to have died in England from swine flu.
SFA says preparation is key
The Small Firms Association has said that businesses must have a policy to deal with a swine flu pandemic and that absenteeism alone could cost small businesses with sick pay schemes €90m a year.
Avine McNally, assistant director of the SFA, said that no business should be adopting a wait-and-see approach.
If a major outbreak were to occur in Ireland, some firms may not have sufficient staff in work to ensure continuance of services and products, she added.
The SFA says companies need to plan for an alternative organisational structure, which may include allowing employees work from home or avail of remote access.
