Dec. 15, 2009 -- No big deal. That's what infectious disease experts are saying about drugmaker Sanofi Pasteur's recall of about 800,000 pediatric doses of its vaccine against pandemic H1N1 influenza because of low potency. The recall was announced by the U.S. Centers for Disease Control and Prevention on Tuesday.

"It is a pain the neck, but not a major crisis," said Dr. William Schaffner, chair of Vanderbilt University School of Medicine's Department of Preventive Medicine in Nashville, Tenn. "This should not discourage people from being vaccinated."

But the recall is hardly a shot in the arm for a swine flu vaccination effort that has in recent months been plagued by delays and supply shortages.

"I suspect most of the consequences will be perceptual," said Stephen Morse, professor in the Department of Epidemiology at the Columbia University Mailman School of Public Health in New York. "But it does add to the embarrassment in a program whose glitches have already been well publicized."

Despite the nature of the recall, children who were vaccinated with the weakened doses should not be revaccinated because the antigen content "is only slightly below the 'specified' range," according to the CDC. In other words, even the weakened level of the vaccine is still expected to be protective.

The recall does not affect any of the vaccine for adults or products from other manufacturers. And according to the CDC, "There are no safety concerns with these lots of H1N1 vaccine. All lots successfully passed pre-release testing for purity, potency, and safety." The strength of vaccines can sometimes decline with time, the agency said in a statement on its Web site.

The weakened potency of the vaccine doses was identified by Sanofi Pasteur during routine quality assurance testing, but the company has not yet determined the cause. Representatives from the company were not immediately available for comment.

Recall Does Not Mean H1N1 Vaccine Unsafe, Experts Say

Most immunization experts agreed that the recall should not be viewed as a black eye for the H1N1 vaccine.

"When there will be over 150 million doses available in the U.S. alone, we should be happy that testing is vigorous and found very little problem thus far," said Dr. Peter Katona, associate professor of Clinical Medicine at the David Geffen School of Medicine at UCLA. "The fact that revaccination isn't even recommended makes this even less of an issue."

Dr. John Treanor, chief of the Infectious Diseases Division of the Department of Medicine at the University of Rochester Medical Center in Rochester, N.Y., noted that the 10 percent drop in potency that has been reported would mean that instead of getting a dose of 15 micrograms from the H1N1 shot, a person would be getting a dose of 13.5 micrograms.

"In studies that we and others have done with seasonal vaccine in adults, there is no substantial difference in the immune response between a dose of 15 micrograms and one of 7.5 micrograms," he said. "So I can't imagine that the effect of a 10 percent decrease in potency of this vaccine would be even noticeable."