GENEVA Flu experts will advise next week whether the world is in a post-peak phase of the H1N1 pandemic, signaling infections are falling in most countries but new waves may still occur, the World Health Organization said on Friday.
The U.N. agency declared last June that the new virus was causing the first influenza pandemic in more than 40 years and raised the alert level to the maximum 6.
The WHO's emergency committee, comprising 15 experts, will review the situation by teleconference on Tuesday but will not declare an end to the pandemic, WHO spokesman Gregory Hartl said.
"We stay at phase 6 or we move to post-peak, those are the only two possibilities," Hartl told a news briefing.
"The post-peak means basically a transition period where most countries have probably seen the peak of activity but it doesn't mean that all countries have. We could see additional waves," he said.
Previous influenza pandemics have been marked by waves of disease activity spread over months, meaning the post-peak period could last for some time, according to the WHO.
"This virus is expected to be a significant threat to people as we go into the fall and winter period," the WHO's top influenza expert, Keiji Fukuda, said on Thursday.
Younger people, especially those with chronic medical conditions, and pregnant women continue to be at a higher risk of infection and viral pneumonia from the H1N1 virus, he said.
The final stage, called the post-pandemic period, is when disease activity returns to levels normally seen for seasonal influenza, according to the Geneva-based agency.
Hartl, referring to next week's agenda, said: "Post-pandemic is not on the cards. It would be to move to what is called a post-peak situation. We would still be in the pandemic."
"So we are not out of a pandemic, this is still not behaving like a seasonal influenza virus," he said.
Australian John MacKenzie heads the 15-member committee, whose confidential recommendations will go to WHO director-general Margaret Chan late on Tuesday.
She is then obliged to inform the 193 member states and Vatican of the decision, which will only be made public on Wednesday at 1000 GMT, according to Hartl.
(WHO pandemic alert scale is at r.reuters.com/cex22j)
(Editing by Jonathan Lynn)