GENEVA, April 14 (Reuters) – The H1N1 flu pandemic is as severe as influenza pandemics in 1957 and 1968 and remains a threat, especially to healthy young adults, the chairman of the WHO’s Emergency Committee said on Wednesday.

John Mackenzie, the Australian expert who heads the independent but secretive advisory body, also said that he was not aware of any of its 15 members being approached by drug companies seeking to influence their decision-making.

“This is just as severe as we saw in 1957 and 1968, with one major difference. We are not seeing deaths in the elderly but we are seeing them in a more important group of the population, healthy young adults,” Mackenzie said in a rare presentation.

“It is much more severe than people tend to talk about,” he told a three-day meeting called to review the way the World Health Organisation (WHO) handled the pandemic.

The official death toll so far from H1N1 is 17,700, but WHO says it will take at least a year or two after the pandemic ends to establish the true number.

The 1957 and 1968 pandemics killed around 2 million and 1 million respectively, according to the WHO. Seasonal flu kills up to 500,000 a year, 90 percent of them frail elderly people.

The Emergency Committee played a key role in advising the United Nations agency on progressively moving up its six-phase scale, leading to declaration of a full pandemic last June.

Phase changes have implications for switching from production of seasonal flu vaccine to pandemic vaccine. Moving to phase 6 also triggered advance purchase agreements that some Western countries had with drug companies.

Swine flu has turned out to be less severe than feared, and critics have said the WHO created needless panic and caused Western governments to stockpile vaccines that went unused.

Mackenzie said he expected the committee to convene again in two or three weeks to advise WHO director-general Margaret Chan on whether the world has moved to a post-peak phase. But he indicated that such a decision remained premature.

“STILL IN A PANDEMIC”

“We still have evidence of the pandemic in Asia and in West Africa,” he said. “We also want to see what happens in a second wave in the southern hemisphere. We have no idea what will happen and have some concerns.

“I would say, yes, we are still in a pandemic phase 6 … We cannot lower our guard.”

Mackenzie said the committee had taken unanimous decisions on difficult issues based on what evidence was available.

“I as chairman was not approached at any stage by the pharmaceutical industry. I don’t know of any member being approached and I would very much doubt it,” he said.

“We did not want to see production of seasonal vaccine discontinued if the pandemic was going to disappear.”

No Emergency Committee members apart from Mackenzie are identified publicly — a policy intended to protect them from commercial or political influence.

David Salisbury, head of the WHO’s vaccine advisory body, the Scientific Advisory Group for Emergencies (SAGE), said it had become clear only last October that a single dose of vaccine would be sufficient to provide immunity for adults, and not two as generally expected.

He also denied that SAGE’s members had been coerced:

“No attempt was made at any time to influence the advice we gave either in terms of the time we gave it or the content. To my knowledge, the industry has done nothing to us other than provide scientific information.”

GlaxoSmithKline (GSK.L) and Sanofi-Aventis (SASY.PA) are among firms that have raced to produce H1N1 vaccines. (Editing by Jonathan Lynn and Kevin Liffey)