Ever-changing virus challenges drugmakers
The swine flu virus is a wily foe whose central weapon against humans is its ability to rapidly change its form.
But the virus also profits from the slow pace at which people technologically adapt to it.
Scientists must decide the components that go into each year’s flu vaccine about six months before the virus shows up — more than enough time for the virus to change in ways that the vaccine cannot defend against. Technical and cost challenges, moreover, limit public health officials’ ability to drastically change the previous year’s vaccine, even if they know the coming flu season will bring different strains.
Dodging a global flu pandemic, in other words, is a little like being told you can make one change in a ship’s course to avoid hitting an iceberg, only the iceberg is six months away.
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Doctors got a new tool against the flu in the late 1990s, when antiviral drugs such as Tamiflu and Relenza came to market. They block a protein called neuraminidase that is found on the surface of the virus and