The Tribunal's focus yesterday turned to seven patients with haemophilia B, who contracted HIV through a blood product manufactured by the Blood Transfusion Service Board in the mid-1980s.
While the seven represent only a small fraction of the 260 haemophiliac victims of hepatitis C and/or HIV from contaminated blood, their cases are of major significance to the inquiry as, arguably, the board was more responsible for their infection than any of the other victims.
The seven were among the last haemophiliacs to contract HIV, the infection having occurred between July 1985 and August 1986. All but one of the 98 haemophilia A HIV victims, in contrast, were infected before April 1st, 1985.
A further distinction was that, while the haemophilia A sufferers were most likely to have been infected by imported commercial blood products, the source of contamination for the haemophilia B victims was a product made in-house by the BTSB.
The seven patients, five of whom died, were identified only by coded numbers. Each was infected by one of two batches of factor 9, made from plasma from up to 1,000 Irish donors between March 1984 and early 1985.
One of the two batches was tested for HIV but showed up negative. Dr Emer Lawlor, the BTSB's deputy medical director, said a "window period" existed during which recently infected blood might not test positive.
She noted, however, that since the late 1980s, screening tests had improved and now the chance of an infection not showing up was about one in 3.3 million.
The BTSB was already using heat-treated factor 8 products for haemophilia A patients and had begun importing heat-treated factor 9 for haemophilia B patients. Some 910 vials of the latter product had been supplied to the board by a US company between February and October, 1986.
Why, then, did the board release an untreated product - a mere 172 vials in the case of one of the batches - to hospitals as late as October 1985?
Dr Lawlor said one reason was that there were lingering fears about possible side-effects from heat-treating factor 9. In particular, she said, there was a concern of an increased risk of patients contracting thrombosis from the product.
There was a "huge debate" in Britain over the pros and cons of heat-treating factor 9, she said, and the BTSB, because it was comparatively less experienced in the area, was awaiting the outcome of that debate.
However, counsel for the tribunal, Mr John Finlay SC, pointed out that as early as January 1985 Prof Ian Temperley, medical director of the National Haemophilia Treatment Centre, app eared satisfied that heat-treating factor 9 was a necessary step. In a letter to the National Drug Administration Board, he said he was purchasing "only" heat-treated commercial products and had "advised Pelican House factor 9 concentrate will be shortly heat-treated."
Moreover by April 1985, said Mr Finlay, there appeared to be an emerging consensus in the US that heat-treated factor 9 was both safe and effective.
He suggested that, far from following the debate on the issue, the BTSB was merely slow to utilise the new technology.
Mr Finlay noted that references to heat-treatment were "remarkably" absent from the minutes of board meetings of the BTSB. This was despite Prof Temperley's letter to the board in December 1984 advising it to "urgently consider" heat-treating all products, including factor 9.
Dr Lawlor said there may have been a perception that because the home-made factor 9 was "Irish product", it was free of infection and did not need heat-treatment.
She will resume her evidence today.