Michael Boylan, managing partner at Augustus Cullen Law and head of its medical negligence group, said there are challenges recruiting expert witnesses because of the links many have with major pharmaceutical companies and with various health product regulatory agencies.

Regulatory authorities, including in Ireland, licensed the use of Pandemrix, a vaccine made by GlaxoSmithKline, to combat the H1N1 virus.

“Without being conspiratorial, very many of the experts in this area have connections with ‘big pharma’; in other words, drug companies who funded their research. A lot of them are also involved with the regulatory agencies who licensed their research. So it’s been a long search to get the experts,” Mr Cullen said.

They had recruited a number of experts, but were “still adding” to the list.

Augustus Cullen Law is representing 46 families in Ireland affected by vaccine-induced narcolepsy, a chronic incurable sleep disorder. SOUND (Suffers of Unique Narcolepsy Disorder), the lobby group working on behalf of those affected, said it has upwards of 70 members, the bulk of them children or adolescents.

Mr Boylan’s firm has initiated legal proceedings on behalf of at least a dozen clients against GlaxoSmithKline Biologicals SA, the health minister, and against the State.

GSK has invoked a government indemnity agreed with the Department of Health in 2007, which requires any compensation claims and costs to be paid out of government funds.

Mr Boylan said they are expecting the State to lodge its defence by the end of the year “if they don’t concede liability”.

However there was “no admission of liability as things stand”, he said.

Mr Boylan said part of their case against GSK would be that its vaccine was in breach of the Liability for Defective Products Act, 1991.

“If we can establish that it was a defective product, and on the face of it, it was not as safe as the consumer was entitled to expect, the onus passes on to Glaxo to prove that it was as safe as could be made given the level of scientific knowledge available and the time to put it into circulation,” he said.

Mr Boylan said they are looking at the addition of the adjuvant ASO3 to Pandemrix as a possible link between the vaccination and narcolepsy. Adjuvants act as a booster for the vaccination and increase the body’s immune response to it.

Mr Boylan said they believe the adjuvant had been added to the vaccine manufactured in the GSK plant in Dresden but not to the vaccine manufactured at GSK’s Canadian plant.

He said “no one has come up with a plausible reason” why in Europe, more than 1,000 people developed narcolepsy post-vaccine, while no spike in narcolepsy was noted in Canada.

An Irish study found there was a 13-fold risk of narcolepsy in vaccinated people in Ireland compared to unvaccinated individuals.