From the December 2003 Idaho Observer:

Experts guessed wrong this year

The prognosticators at the CDC were way off this year. They assumed that A/Panama flu would be dominant and the vaccine was tailored for this variety instead A/Fujian, which has become the dominant strain. In one study of some 70 patients of whose influenza was carefully identified, only 22 percent had A/Panama -- the flu for which the vaccine was designed. The remainder had A/Fujian.

Because A/Panama and A/Fujian are similar type strains of influenza, the CDC still recommends flu shots. They explain that, while the vaccine may be less effective against the A/Fujian flu “...it is expected that the current vaccine will offer some cross protective immunity and reduce the severity of disease.”

In other words, the CDC is admitting it guessed wrong this year and, to save face, is saying that a shot of the partially-effective vaccine is better than no shot at all

The CDC had an early warning about the A/Fujian flu as it was the dominant strain during the southern hemisphere flu season, which peaked last summer. Summer here is, of course, winter there. Why the CDC did not anticipate that A/Fujian would be dominant in the northern hemisphere this year remains to be explained.