The woman was from the south of the country and had “an underlying medical condition,” the Department of Health stated.
Neither the department nor the HSE was prepared to disclose any further details last night.
Health Minister Mary Harney, on behalf of her own department and the HSE, offered sympathy to the family and friends of the patient.
In the past week five people with the H1N1 virus have died, including a teenage boy.
Meanwhile, a senior EU official has warned that schools, arts and sports events with confirmed swine flu cases should face “immediate” closure and cancellation.
Speaking after the EU claimed 30% of people could become infected across all member states over the coming weeks, European health commissioner Androulla Vassiliou said the closure plans are vital to prevent further illnesses.
The senior official said the virus is spreading at such a level that one in three people could be infected by the end of the year. And in a clear warning over the seriousness of the virus, the EU official added that without the tough measures a rise in mortalities is likely.
“From the information we have, up to 30% of the [EU] population could catch swine flu. In this event we must unfortunately expect a significant number of deaths,” the Cypriot commissioner said.
“The virus may evolve and become significantly more aggressive in the coming months,” she explained, adding that such a situation meant the temporary cancellation of work at infected schools and sporting events should be compulsory.
Ms Vassiliou’s comments were made after outbreaks at two Irish primary schools left almost half the pupils of one school reporting symptoms of the virus.
Approximately 40 pupils in one Co Carlow school, which had one confirmed case last Friday, have reported flu-like symptoms and have been advised to remain at home.
The second school, which is located in Co Kildare and has two confirmed cases, has experienced a high rate of absenteeism with parents reporting their children to be experiencing symptoms associated with the illness.
Ballinkillen National School, Mhuine Beag, Co Carlow, had issued a letter to parents last week under HSE guidance that if students were showing flu-like symptoms they should be kept out of school.
There are 109 students in the four-teacher school.
Two cases of the virus were also confirmed at the Patrician Primary School in Newbridge, Co Kildare, last week.
Further cases in recent days have also included three footballers and two backroom staff at Bolton Wanderers FC in Britain who are suspected to have contracted the virus.
GPs in Ireland are treating 7,000 new cases every week, with the rate of infection rising dramatically from 97.1 per 100,000 population a fortnight ago to 158.8 per 100,000 last week. Updated national figures are due to be released by the Department of Health and HSE tomorrow.
Meanwhile, staff at one of the country’s most overcrowded prisons are examining whether an inmate has been infected by swine flu.
It is understood that a prisoner from Dublin who is suspected to have contracted the virus was transferred to Cork prison in recent weeks, and has since developed symptoms which could be linked to the infection.
A spokesperson for the Irish Prison Service said while a number of suspected cases have been reported in jails across the country, no cases have been confirmed in any facility. The spokesperson added that each prison has a site-specific “contingency plan”.