GENEVA, Switzerland (UPDATE) - The World Health Organisation will announce later on Tuesday whether the H1N1 flu outbreak has been downgraded from a pandemic after influenza experts reviewed its status in previously undisclosed talks, the WHO said.
The Emergency Committee of experts has given its assessment to the WHO, a United Nations agency, and its director-general Margaret Chan, after reviewing epidemiological data about current cases, mainly from the southern hemisphere, spokesman Gregory Hartl said.
"The Emergency Committee made its recommendation to the director-general who is in the process of finalising the wording of the recommendation," Hartl told a news briefing.
Chan, who participated in the experts' debate from her native Hong Kong, will make the announcement at a virtual news conference starting at 1300 GMT, a WHO statement said.
The experts' discussions by teleconference -- shrouded in secrecy -- lasted nearly three hours on Tuesday, Hartl said.
Health officials from countries currently reporting human cases of H1N1 -- including Argentina, Australia, India, New Zealand and South Africa -- made presentations about the situation to the experts, according to Hartl.
In June 2009, the WHO declared that a new swine flu virus, H1N1, which emerged in the United States and Mexico, was causing the first pandemic in more than 40 years. A full pandemic corresponds to phase 6 on the WHO's six-point scale for measuring the spread of a disease.
'Post-peak' or 'post-pandemic'?
Experts have advised Chan on whether the world is still in a pandemic or has moved either to a "post-peak" or "post-pandemic" phase, Hartl said.
They analysed the current level of infections in the southern hemisphere, where it is winter, and examined whether H1N1 is behaving more like a seasonal flu.
The WHO's assessment of whether the disease is a pandemic or not is important for national health authorities, and would affect government plans to stockpile and distribute vaccines.
Dozens of companies make influenza vaccines, including Sanofi-Aventis, GlaxoSmithKline, Novartis, AstraZeneca and CSL.
The WHO, in its latest weekly update issued last Friday, said: "Globally, pandemic influenza transmission remains most active in parts of South Asia and in limited areas of tropical South and Central America. In the temperate zone of the southern hemisphere, overall seasonal and pandemic influenza activity remains low, except in South Africa..."
In Argentina, Chile, New Zealand, and Australia, "overall influenza activity remains low and below levels observed during recent, mild, pre-pandemic influenza seasons", it added.
More than 18,449 people worldwide are confirmed to have died from H1N1 infections, including many pregnant women and young people. But the WHO says that it will take at least a year after the pandemic ends to determine the true death toll, which is likely to be much higher.
John MacKenzie, an Australian expert, chairs the committee of 15 external international experts.
The identities of the experts apart from MacKenzie are kept secret to shield them from influence from the pharmaceutical industry, governments and other interest groups.
Editing by Jonathan Lynn and David Stamp