A Dose of Reality
An eagerly awaited bird flu vaccine comes up short
There is a protective shot against bird flu, researchers reported last week. An occasion for joy and relief? Not quite. The vaccine works only half the time, and it has to be given in such large amounts that there would not be enough to go around. Vaccine makers may be able to produce shots for only 75 million people, but "we'd want to protect close to 200 million" in the United States alone, says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. "We're not going to be ready." At least not with this vaccine version.
The shots were given to 451 healthy adults in the United States, doctors reported in last week's New England Journal of Medicine. They tried several different dose levels. The best results: If people were given two shots at a hefty 90 micrograms each, about half of them developed a strong immune response. By comparison, seasonal flu shots take just one injection at 15 micrograms. "It took 12 times the usual dose to protect half of the people who got it," says infectious disease specialist Gregory Poland, who runs the vaccine research group at the Mayo Clinic. "Clearly this isn't the answer."
But it may be a starting point, he adds, for there are ways to get a bigger bang with a smaller dose. Tests on this vaccine are now underway with adjuvants, added chemicals that can boost the immune response so vaccine makers can shrink the dose size and thus stretch the supply. "We should have answers in about six to 12 months," Poland says. "This is really a race against time."
This story appears in the April 10, 2006 print edition of U.S. News & World Report.
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