Feb. 19, 2004 -- Will changes to next season's flu vaccine mean
Feb. 19, 2004 -- Will changes to next season's flu vaccine mean better protection? That depends on which flu we'll be dealing with.
This year's vaccine didn't work as well as had been hoped. That's because a new "drift" variant -- the Fujian flu -- appeared after the vaccine was already in production.
The FDA today completed a two-day meeting to decide on exactly which flu viruses to include in next season's vaccine. The FDA voted to tentatively accept the recommendations of the World Health Organization. Those recommendations:
- Change the vaccine's Panama type A component to Fujian-like type A.
- Change the vaccine's Hong Kong type B component to Shanghai-like type B.
- Keep the vaccine's New Caledonia type A component.
The panel will wait until the last minute -- in mid-March -- to finalize its recommendation.
Some experts say the WHO and the FDA should have put a Fujian component in last year's vaccine. But CDC officials say the Fujian strain appeared too late to be included.
Why does it take so long to make the vaccine? Current vaccine technology grows flu vaccine in hen's eggs. It takes at least several months to gather the tens of millions of eggs needed and to grow, prepare, test, license, package, and ship the vaccine.
How Well Did Last Year's Vaccine Work?
Even in a good year -- when the flu vaccine is a perfect match with the flu virus that actually circulates -- the vaccine is not 100% effective. In such years, the flu vaccine offers 70% to 90% protection. Healthy adults get the best protection, while the elderly and children vaccinated for the first time usually get somewhat less protection.
At today's session of the FDA flu vaccine meeting, CDC epidemiologist Carolyn Bridges, MD, reported on how well the 2003-2004 flu vaccine worked. Data are still coming in, but it looks as though the vaccine was neither as good as had been hoped nor as bad as had been feared.
Bridges reported very preliminary data from a study of 64-year-olds who got their flu shots as recommended. Those who came down with flu-like symptoms were tested to make sure they really had the flu.
"The range for these 64-year-olds -- and this is very preliminary data -- seemed to be about 16% to 68% for laboratory-confirmed influenza," Bridges tells WebMD. "So there was demonstrable vaccine efficacy against lab-confirmed flu. It was likely somewhat lower than if you'd had an optimal match. But it does appear that vaccination had a benefit."
