* Global pandemic alert remains at level five out of six * No evidence of sustained flu spread outside North America * WHO official says still expects move to level six (Adds details on virus, alert level, and emergency committee) By Laura MacInnis GENEVA, May 2 (Reuters) - An H1N1 flu pandemic is still "imminent" even though it has not yet spread in a sustained way outside North America, a World Health Organisation official said on Saturday. Michael Ryan, WHO Director of Global Alert and Response, said the alert level would probably be raised from its five now to the top of the six-stage scale. "We have no evidence of sustained community spread outside North America," he told a news briefing at the U.N. agency's Geneva headquarters. "We are still at phase five. "At the present time I would still propose that a pandemic is imminent, because we are seeing the disease spread," Ryan said. "At this point we have to expect that phase six will be reached, we have to hope that it is not reached." WHO Director-General Margaret Chan raised the pandemic alert level from four to five on Wednesday, a move that helped intensify pharmaceutical efforts to produce antiviral drugs and find a vaccine to fight the new strain widely known as swine flu. Level five indicates that a pandemic -- the global spread of a disease -- is "imminent". The new virus strain that sparked alarm when it was found to kill young adults in Mexico has had milder effects as it spread to the United States, Canada, Europe and Asia. Mexican health authorities have revised down their suspected death toll from H1N1 to 101 from as many as 176, after receiving negative lab test results that raised hopes it may not be as serious as first feared. NO RELIEF YET But Ryan, who runs the WHO's monitoring for the new strain as well as other infectious diseases such as Ebola, said it may be too early to breathe a sigh of relief. "I would be very pleased if it turns out this virus is weaker than it could be. I'd be the most happy man in the world," he told journalists, while warning that all viruses can mutate and become more dangerous, and must be closely watched. "There are many things that can lead to an outcome like that," he said, when asked about the new Mexican estimates. "It would be imprudent at this point to take too much reassurance." Chan, who prior to leading the WHO had fought outbreaks of SARS and bird flu as Hong Kong's health director, is holding morning meetings to review all data on the H1N1 outbreak and to decide whether to convene the Emergency Committee which advises her on the appropriate pandemic alert level. A WHO spokesman said that while there are no meetings yet scheduled, that panel would compare notes on the outbreak at least once and probably several times before the alert level is raised to six. The designation of a full-blown pandemic would not, however, necessarily mean that the WHO expects the new virus strain to be deadly around the world. "Pandemics are serious. But it is important to note that phase six describes geographic spread of the disease and not its severity. We do now know how severe or mild this pandemic might be," Ryan said. Different countries may be affected differently by the flu, depending on how the disease spreads in each area, Ryan said. Other factors including the number of people with HIV/AIDS could also affect flu's severity as it reaches poorer countries. To prepare for this, the WHO has begun to send 2.4 million doses of antivirals to 72 countries including Mexico from stocks donated by Roche <ROG.VX> in 2005 and 2006. It is also adding to its regional stockpiles around the world and seeking to dispatch diagnostic kits to WHO reference labs worldwide to help them quickly identify H1N1 infections. Despite concerns about large public gatherings and events in areas touched by the flu, the WHO still plans to go ahead with its annual World Health Assembly, which will this month draw health ministers and officials from across the globe to Geneva. (Reporting by Laura MacInnis; editing by Richard Meares)
People walk inside a subway station in Mexico City May 2, 2009. New laboratory data showed fewer people have died in Mexico than first thought from a new influenza strain, a ...
