those that have evolved slightly and do not precisely match the strain of virus used in the vaccine. "We think such a vaccine could offer a better option to governments with regard to stockpiling," Innis said. The H5N1 strain of avian influenza has spread rapidly out of eastern Asia in recent months, causing outbreaks in India, infecting birds in western Europe, across parts of the Middle East and down into West Africa. It almost exclusively infects birds but has sickened 186 people in eight countries and has killed 105 of them. Experts believe it poses the greatest threat yet of a pandemic, a global epidemic of flu that could kill millions, if it acquires the ability to pass easily from human to human. A key challenge in the race to develop a potential pandemic flu vaccine is how to make the maximum number of shots from the minimum amount of antigen -- the killed virus used to prep the immune system. Governments are also urging companies to step up production capacity. Existing vaccine factories can make only 900 million doses of influenza vaccine globally -- far short of what would be needed in a pandemic when billions of people would need to be vaccinated. Stout said Glaxo was gearing up for this, working on a new factory in Pennsylvania that will use cell cultures to make flu vaccines, instead of the current, old-fashioned and uncertain method in which the vaccine antigen virus is grown in eggs. Glaxo also bought a Canadian influenza vaccine manufacturer, ID Biomedical Corporation. Chiron Corp and MedImmune are also working to develop a vaccine against H5N1. The normal seasonal flu vaccine provides no protection against H5N1. Stout said Glaxo was also working to boost production of Relenza, its influenza drug. Unlike the preferred flu drug, Roche AG and Gilead Sciences' Tamiflu, Relenza is inhaled. But like Tamiflu, Relenza, also known as zanamivir, is in short supply. --SP 22 51 Local Time 19 51 GMT
