Last year's flu vaccine was good, but not perfect

The ever-mutating influenza viruses are formidable, but they are not unbeatable foes for vaccine developers.

By Susan J. Landers, AMNews staff. Sept. 6, 2004.

Washington -- Viewing the glass as half-full, Centers for Disease Control and Prevention officials and other infectious disease specialists are pointing to last year's influenza vaccine as a success, even though it wasn't perfectly matched to the flu it was formulated to fight.

Two CDC studies, one on children and the other on adults, found that the vaccine was effective in about half the cases.

The results should persuade more people that an annual flu shot carries important health benefits, said William Schaffner, MD, professor of preventive medicine at Vanderbilt Medical Center in Nashville, Tenn.

"The best protection is achieved by routinely getting your flu shot each autumn and knowing that the protection is going to be either pretty good or great. But at the very least, it will be pretty good, and that's better than having no protection at all," he said.

The CDC determined that the vaccine was effective about 52% of the time at preventing influenza among the Colorado adults studied. The vaccine's effectiveness ranged from 25% to 49% among the children, said Carolyn Bridges, MD, a medical epidemiologist with the CDC's National Immunization Program.

The finding for children was less definitive because laboratory confirmation of the flu was not the end point in that study, whereas in the study on adults, influenza cases were laboratory-confirmed. The researchers looked at children who had received a diagnosis of a respiratory illness, which could include a number of ailments that are not halted by the flu vaccine.