Is flu pandemic waning? Not yet, experts say

WASHINGTON (Reuters) - Has the swine flu pandemic peaked globally? Not quite, World Health Organization advisers decided on Tuesday.

WHO is taking a big risk in making such an announcement at all, and the wording of WHO Director-General Dr. Margaret Chan's decision, to be announced on Wednesday, will affect whether governments, companies and the public pay attention, or decide, wrongly, that the crisis is all over, public health experts say.

No matter what happens, some public health officials fear that the moderate nature of the H1N1 pandemic, which emerged in April and is dying down in the Americas and Europe, may make people complacent about the next one.

And the risk remains that H1N1 could come roaring back -- something viruses have done in past pandemics.

"Our recommendation is certainly that countries don't change their policies if we were to move to post-peak," WHO spokesman Gregory Hartl said in a telephone interview.

"We would recommend that countries continue to do what they have been doing."

So why even make an announcement?

"That certainly was a question that was debated today," Hartl said.

WHO declared in June that H1N1 swine flu was causing a pandemic -- the first flu pandemic in 40 years -- after it was first discovered in Mexico and the United States and spread around the world within six weeks.

It was the U.N. agency's first chance to use its six-phase pandemic plan, which was broadly criticized because it describes the extent and spread of a new infection but has little way to convey virulence.

Dr. Nancy Cox of the U.S. Centers for Disease Control and Prevention is a member of WHO's emergency committee and one of the world's leading influenza experts. She said the group has been struggling to make sure it gets the point across correctly.

"It is very, very difficult to get the wording exactly right," Cox said in a telephone interview.

COMPLEX MESSAGE

"We expect the 2009 H1N1 virus to be around for a long time. It is a complex kind of message."

Risk communications expert Peter Sandman says WHO and other public health agencies will be keen to make clear that influenza is unpredictable.

"Whether they declare that we are in the post-peak phase or not, it will be very important for them to say that the decision is tentative," Sandman said in a telephone interview.

"Either they will be saying that it looks like we are in a in post-peak phase but don't let down your guard because there could be another wave...or they are going to say it is a little early to declare it post-peak and we are going to wait," he added.

Adding to the difficulty, H1N1 caused at worst a moderate pandemic, in terms of numbers. Seasonal influenza kills 250,000 to 500,000 people globally and 36,000 people in the United States alone every year. WHO has no global estimates but the CDC projects that H1N1 has killed up to 17,000 people.

It also appears to have displaced seasonal influenza, at least for the time being, although that could change at any moment as well.

"People were thinking that a pandemic has to be some kind of cataclysmic event. It is a loaded word," Cox said.

But H1N1 was worse than seasonal flu in some ways. Ninety percent of victims were children and young adults, in contrast to seasonal flu, whose toll is usually largely among the frail elderly.

And it hit during spring, summer and autumn months in the northern hemisphere, when there is usually little or no flu activity.

Nonetheless, the nature of the pandemic has created a load of skeptics, Sandman said.

"We came into the pandemic with a very high expectation of deadliness. We are going to come into the next pandemic with a very low expectation of deadliness," Sandman said.

"And the next pandemic could be next week. Whatever it is, it is going to be incredibly hard to get people to take it seriously."

(Editing by Cynthia Osterman)