The director of the U.S. Centers for Disease Control and Prevention said today that Health and Human Services Secretary Tommy Thompson has finalized a deal to buy investigational flu vaccines from international manufacturers, for use this flu season.

Dr. Julie Geberding, speaking at an American Medical Association forum on the current flu vaccine shortage, said that “since these vaccines are investigational they will require informed consent.”

Asked for specifics, Geberding said “a standard medical consent will be required.”

She declined to elaborate on the number of investigational vaccine doses covered by the new agreement. “Secretary Thompson will answer all those questions,” she said.

During the same presentation, Geberding said the CDC considers the likelihood of a bird flu pandemic to be “very high.”

Dr. David R. Johnson, director of scientific and medical affairs at Aventis Pasteur, said that a bird flu pandemic is generally considered “a question of when, not if.” But while Geberding said some data suggest human-to-human transmission of bird flu, he pointed out that “there is no evidence yet of efficient human-to-human transmission.”

When asked about CDC efforts to avoid a vaccine shortage similar to the one experienced this year when the UK pulled the manufacturing license of vaccine maker Chiron, Geberding said the CDC “can never guarantee that a shortage won’t happen again.”

She continued: “The best we can do is to identify maximum, safe production goals, work with the Food and Drug Administration to bring Chiron back on line, which we are doing; and scale up our investment in a flu vaccine stockpile to guarantee a market to manufacturers. But what we really need is more manufacturers making more vaccine.”