Pressure mounts on Harris as he admits knowing of hepatitis probe last January
Health Minister Simon Harris was informed as early as last January that an Irish patient had tested positive for hepatitis B which was "probably transmitted" through a blood transfusion.
However, the serious incident was not made public by the Irish Blood Transfusion Service (IBTS) until this week.
The delay in making the incident public has raised major questions, particularly in light of the blood scandal which engulfed the service in the 1990s, leading to the infection of more than 1,000 mothers with hepatitis C.
The Irish Independent has learned that the IBTS found out in December last year that one of its donors, who had given blood, had hepatitis B, but it had not been picked up at the time of donation.
This was because the donor was newly infected and the virus cannot be detected during the first two-week window period.
The IBTS made public this week that the donor's blood had contaminated a transfusion which was given to a hospital patient, and caused them to be infected with the virus as a result.
Hepatitis B is a serious infection. While many patients clear it, the virus, if untreated, can attack the liver and cause cirrhosis or cancer.
Asked why the minister did not go public, a spokeswoman said: "He was aware the IBTS would make a public statement on the matter at the appropriate time, bearing in mind donor and recipient confidentiality."
It needed to be confirmed the virus was passed on by transfusion and "this has now happened".
The minister told the Irish Independent: "The IBTS advise that this is a one in two million event. When the hepatitis B infection was diagnosed, the matter was reported and followed up in an effective and timely way. There is no ongoing risk to the blood supply or to patient safety."
The IBTS said it was investigating the incident until August, including recalling all donors whose blood was used in the transfusion given to the patient who ended up being infected.
Asked if the minister is to instigate any external inquiry, the Department of Health said the IBTS takes part in external quality assurance schemes operated by international institutions.
Earlier yesterday, Dr Stephen Field, medical and scientific director of the IBTS, told Kfm radio in Kildare that it could probably have made the incident public before this week.
However, he insisted it needed to be investigated.
When pressed further on the delay by Kfm's Shane Beatty, he ended the phone interview.
The blood contamination scare is one of a litany of major issues which has confronted the minister and the health service.
He faces into a winter of another potentially serious trolley crisis. Earlier this week, there were 415 patients on trolleys across the country, including 36 in Cork University Hospital.
The gridlock comes before the onset of the cold and flu season which will see even more intense overcrowding, particularly due to admissions by elderly patients.
Mr Harris is also faced with hospital waiting lists that have reached record levels.
The latest figures show a massive 687,00 on some form of waiting list.
The numbers jumped by 9,000 in just a month between June and July. There are 86,111 patients waiting for surgery.
The minister will also be expected to deliver a new contract for GPs by the end of the year, as pressure mounts to provide free GP care for children aged under 12.
Hospitals are also beset with a shortage of specialist staff, including consultants with an ongoing lack of nurses.