TORONTO - The H1N1 pandemic is likely to be officially consigned to the history books in the next week or so, says Dr. Margaret Chan, director general of the World Health Organization.

Chan suggests that the global health agency and the experts that advise it on this matter are feeling increasingly confident the virus responsible for the 2009 pandemic is acquiring the patterns of seasonal flu viruses.

"All in all, people feel that the overall picture looks like we are ready to declare post-pandemic globally very soon," Chan said in an interview from Hong Kong.

The so-called emergency committee is likely to convene a meeting this week, she suggests. The committee is a panel of external and as yet unidentified experts who have advised Chan on major matters related to the pandemic. Chan, who has been harshly criticized for not identifying the members of the committee, has promised to do so once the pandemic is declared over.

The "all clear" could be sounded after that meeting, though outbreaks of H1N1 in schools in parts of New Zealand may delay the decision a little.

"We need to look at the situation. Another week or two? I cannot predict," Chan says.

The call will be made on advice from the emergency committee and with input of the countries currently most affected by H1N1 activity. New Zealand officials will be questioned on how the virus is behaving there. And the committee will likely want to hear from India, which is reporting quite a bit of H1N1 activity of late.

The fact that the announcement still remains to be made may take some people by surprise. In much of the Northern Hemisphere, H1N1's second wave peaked last fall and there's been remarkably little flu activity since the start of the year.

Chan concedes she's been queried about why the WHO hasn't declared the pandemic over before now.

"If I were a scientist, a minister of health living in a country in the Northern Hemisphere, I would ask the same question," she says.

"(But) I can't do it just for the Northern Hemisphere. Because I have no idea how the Southern Hemisphere will behave (during its winter). And what if they turn a bad corner?"

The WHO has been watching for a number of signs it believes are key to determining that H1N1 is morphing into a seasonal flu virus.

One critical indicator is the timing of flu activity. In the Northern and Southern Hemispheres, flu viruses mainly circulate during winter months. But during pandemics, widespread out-of-season transmission can occur.

That's exactly what happened last summer in parts of the Northern Hemisphere. But H1N1 hasn't given a repeat performance this summer.

The WHO has also been looking for evidence that -- as is normal with seasonal flu -- a variety of viruses are circulating. For months after H1N1's emergence, there was virtually no sign of other influenza A or influenza B viruses. Lately it's been much more of a mixed picture.

"In a nutshell I'm looking for several things," explains Chan, who concedes most of these criteria appear to have been satisfied.

"Lack of out-of-season outbreaks. Reduced intensity of outbreaks. And reduced dominance of the H1N1 pandemic virus and evidence of some population immunity (to the virus)."

Chan admits she's eager to move to the post-pandemic phase so the agency can focus on analyzing what happened and incorporating the knowledge gained into plans for future pandemics.

While it has claimed at least 18,500 lives globally, the outbreak was far milder than flu experts had been anticipating. Hospitals didn't get pushed beyond capacity. Doctors didn't have to make the awful choice of who got a ventilator and who did not.

But despite the relative mildness of the disease H1N1 caused, plenty of cracks appeared in the public health responses.

Estimates of how soon vaccine could be made proved to be overly optimistic and redistributing donated vaccine to developing countries proved to be a far slower process than anticipated.

In Canada, mass vaccination efforts were chaotic in places. As Ontario's chief medical officer of health, Dr. Arlene King, put it in her report on the outbreak, there wasn't enough vaccine when people wanted it, and when vaccine was plentiful people were no longer interested.

Chan knows already there are changes that need to be made.

"We planned for the worst case scenario," she says, referring to the fact that pandemic planners were driven by fears the dangerous H5N1 bird flu virus would trigger the next pandemic.

"If there's something we can do better ... I think we would advise people in pandemic preparedness planning in future, (that) we should look at the best case scenario, the intermediate scenario and the worst case scenario."

"That would provide us flexibility to move up and down the scale."

The difficulty of tailoring the plans on the fly to a much milder threat created the impression that the response was expensive overkill. In Europe, in particular, the WHO and national governments have come under heavy fire for wasting money on vaccine and drugs that critics graced with the luxury of hindsight have deemed were unneeded.

The WHO has even faced allegations it called the pandemic to pad the pockets of Big Pharma -- a charge Chan has fiercely denied.

Instead of excruciating medical dilemmas, this pandemic posed tough communications issues, Chan suggests.

"Having a virus causing a mild disease is the biggest challenge for all of us to manage the perception and the expectation," she says.

"And that is actually why we say that next time around, we really need to provide flexibility for different scenarios."

"And then countries need to upgrade or downgrade based on their country-specific situation. And when they do that, they should not be criticized for changing the goal posts."

She says she doesn't mind criticism; in a position like hers, she expects it and doesn't personalize it. But Chan does see irony in the flak aimed at her agency and at pandemic preparedness planners in general, who for years operated under the mantra "Hope for the best and prepare for the worst."

"You look at the criticism against BP," she says, referring to the disastrous oil spill in the Gulf of Mexico.

"One of the very fierce criticisms is that they have no worst case scenario planning for contingency. And in this case I have to say public health officials in all the countries where they can afford it have really done their best in terms of planning a worst case scenario. And that's why they have spare vaccines."