THE outbreak of a virulent stomach bug, which is striking thousands of victims, is expected to last for up to two months.
The huge spike in cases of the winter vomiting bug, which causes violent vomiting and diarrhoea, may not peak until the new year.
A spokesman for the country's disease watchdog said it is difficult to predict its pattern but the existing high rates of illness are likely to continue for another eight to 10 weeks.
It is estimated that between 1,000 and 5,000 people a week are being laid low by the virus, which is hitting hospitals, schools, nursing homes, creches, hotels and workplaces.
The current strain, which is highly infectious, has been circulating here for the past five years, the Health Protection Surveillance Centre revealed.
It emerged earlier this week that there has been a fourfold increase in reported cases of the bug in recent weeks.
Outbreaks in a number of hospitals will mean that adult and child patients who cannot go home for Christmas will also have to endure restricted visits from family and friends.
A spokesman for St Vincent's hospital in Dublin, which is struggling with a particularly bad outbreak, said 92 patients and 70 staff were laid low by the illness.
He told the Irish Independent:"So far there are approximately 10 beds closed to new admissions.The strain on services is a result of so many staff being affected. So far no service has had to be suspended."
Asked if the visitor restrictions will continue over Christmas he said: "As of now, it is intended to maintain visitor restrictions at the current level."
The hospitals that are worst affected are concerned that there will be an increase in the numbers of children visiting during the Christmas holidays, and have asked that children under 12 years of age be not brought on visits.
People who have symptoms such as 'upset tummy' should not attend hospital but contact their GP in the first instance.
"Patients who attend hospital for appointments or need emergency care should attend the hospital as normal."
Temple Street children's hospital in Dublin said its visiting restrictions remain in place due to a rise in infections including the winter vomiting bug.
"These infections can be severe if they spread among children already in hospital," a spokesman said.