Flu vaccine manufacturers are opening the production throttle to make the billions of doses of vaccine that will be needed to protect against the newly declared H1N1 pandemic, Reuters reported. Work on developing an H1N1 vaccine is already under way at leading companies, whose factories will be ready to switch to making a pandemic shot in around two weeks' time, when normal season flu vaccine production is complete. "Our recommendation is they need to finish the seasonal vaccine and then move over," World Health Organisation Director-General Margaret Chan told reporters on Thursday. Wayne Pisano, head of vaccines at Sanofi-Aventis, the world's largest flu vaccine supplier, said his company would "produce the largest number of doses of vaccine in the shortest time frame". Still, it will be another four months before the first supply of bulk concentrate vaccine is ready, he added. Chan said there would be no H1N1 vaccine ready before September but she noted that the virus, which causes only mild disease in most people, was so far proving fairly stable. Other experts agreed the world had a breathing space to make a vaccine -- seen as the best defence against the spread of infection -- before the start of the next northern hemisphere winter, when the new flu strain might start to mutate. "We do seem to be lucky that this is not a particular nasty virus, although it does look increasingly as though many of us will have a few extra days' off work sometime this year," said Robert Dingwall of University of Nottingham. Drugmakers have obtained the new influenza A (H1N1) seed virus in the past two weeks. But they still don't know how much vaccine they will be able to manufacture, since this depends on how easily the new virus strain grows in chicken eggs, which are used for commercial production. Recent investment in extra capacity means companies like Sanofi, GlaxoSmithKline and Novartis are in far better shape to meet the challenge of a pandemic than five years ago, when a single factory closure in northwest England left the world worryingly short of seasonal flu shots. Drug companies have already secured some large orders for H1N1 vaccine from governments in Europe and North America, and fresh ones are expected now that the WHO has declared H1N1 a full-blown "phase 6" pandemic. That helped lift shares in Glaxo, Sanofi and Novartis by between 2 and 4.5 percent in New York trade on Thursday.
