TORONTO - It's too soon to think about consigning the H1N1 pandemic to the history books, the World Health Organization's top flu expert said Thursday.

Dr. Keiji Fukuda said though flu activity caused by the pandemic virus appears to have peaked in the United States and Canada, that isn't true for other parts of the Northern Hemisphere. And he said it remains to be seen whether places will experience a third wave of infections. "In the Northern Hemisphere, we continue to see an up and down pattern by countries. And so what you see in one country is not necessarily what you are seeing in another country," Fukuda, special adviser to WHO Director-General Margaret Chan on pandemic influenza, said in a teleconference briefing.

"Still at this point overall it's too early to say whether activity is peaking in the Northern Hemisphere. And at this point it is also not possible to predict what we are going to be seeing in the springtime."

He said the WHO will probably explore the issue of when to declare the pandemic over at some point in 2010.

When it does, Fukuda said, it will seek counsel from outside experts and advisory bodies, "to try to get the best scientific picture of where we are in the pandemic, whether we should expect third waves to come in countries or not and whether we think that there's convincing information to say that we are really moving away from the pandemic period."

It appears the WHO's reliance on expert advisers has provoked suspicions in some quarters, with media reports from Northern Europe suggesting some of those who counsel the global health agency have ties with the pharmaceutical industry that may colour the advice they give.

The WHO issued a statement Thursday on the allegations, which are also levelled on some blogs on the Internet.

The agency said all experts who advise the WHO do so for free and must disclose any potential conflicts of interest. Those statements are available on the WHO's website.

"Allegations of undeclared conflicts of interest are taken very seriously by WHO, and are immediately investigated," the statement said.

It suggested the relative mildness of this outbreak -- which followed on years of preparations inspired by fears a disastrous pandemic caused by the H5N1 virus might be looming -- may be contributing to the belief conflicts of interest might have been at play in the declaration of the pandemic.

"Adjusting public perceptions to suit a far less lethal virus has been problematic," the WHO admitted.

"Given the discrepancy between what was expected and what has happened, a search for ulterior motives on the part of WHO and its scientific advisers is understandable, though without justification."

On the issue of the relative lack of severity of the pandemic, Fukuda said a more accurate picture of the toll of the virus will take a couple of years to come into focus. And in the meantime, it would be best to remember the virus isn't done yet.

"I think at this point it's fair to say that we still haven't fully gone through the pandemic and that it is possible that there could be unexpected events which occur as we continue to go through."

"But I think the other point is simply true that it is quite possible to have a pandemic on the milder side. And if we are experiencing that and the number of serious cases is kept down, then it is something again for which we should all be thankful."