Even as federal officials try to round up extra doses of the flu vaccine, many experts are wondering just how much protection the shots will give the millions who have taken them.
Vaccine makers produced 83 million doses this year, but the early and intense outbreak in some Western states has dried up supplies in many places. The Centers for Disease Control and Prevention said Tuesday it is trying to redistribute what is left and might buy additional doses from a British maker.
"The main concern we are facing is the gap between demand for the vaccine and the supply," said Dr. Julie Gerberding, the CDC's head.
The flu shot available this year was formulated to protect against three strains of the virus. But the strain actually circulating is somewhat different, and it is probably too late to develop an extra shot.
Meanwhile, doctors continue to urge people to get vaccinated, even though supplies are running short, because the vaccine may help make the flu less severe, even if it fails to give complete protection. It also protects against two other flu strains that could appear later in the season.
Dr. Sandra Kemmerly, associate head of infectious diseases at the Oschner Clinic in New Orleans, said there is already anecdotal evidence that the shots are helping people escape the worst of the flu.
"Of the people we are seeing who were vaccinated and have flu-like symptoms, it is much milder than if they had not been vaccinated at all," she said.
Dr. Theodore Eickhoff of the University of Colorado, a member of the FDA advisory committee that chose this year's vaccine, estimated it will be less than 50 percent effective at preventing the flu. "It's a guess based on prior years' experience with variant strains," he said.
Dr. William Schaffner, head of preventive medicine at Vanderbilt University, noted that even a vaccine that is 50 percent effective may turn a serious illness into a milder one and help protect those who are especially vulnerable, such as the elderly, against pneumonia and death.
The CDC said flu is now widespread in at least 13 states, and as of last week, it was everywhere except Massachusetts and Washington, D.C.
EDITOR'S NOTE: Medical Editor Daniel Q. Haney is a special correspondent for The Associated Press.
On the Net: