Originally posted in MedPage Today
by Todd Neale, MedPage Today Staff Writer
Sanofi Pasteur has recalled about 800,000 pediatric doses of its vaccine against pandemic H1N1 influenza because of low potency, the CDC announced, but the agency is not calling for revaccinations.
The recall does not affect any of the vaccine for adults or products from other manufacturers.
According to the CDC, “There are no safety concerns with these lots of H1N1 vaccine. All lots successfully passed prerelease 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.
Children who were vaccinated with the weakened doses should not be revaccinated because the antigen content “is only slightly below the ‘specified’ range,” the CDC said. That level is still expected to be protective.
In general, immunization experts did not seem overly concerned with the recall.
“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,” Peter Katona, MD, of the University of California Los Angeles, wrote in an e-mail. “The fact that revaccination isn’t even recommended makes this even less of an issue.”
John Treanor, MD, of the University of Rochester in New York, said in an e-mail that “a 10% drop in potency would mean, effectively, instead of getting a dose of 15 µg a person would be getting a dose of 13.5 µg.”
“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 µg and one of 7.5 µg, so I can’t imagine that the effect of a 10% decrease in potency of this vaccine would be even noticeable,” he said.
Stephen Morse, PhD, of Columbia, said in an e-mail, “I suspect most of the consequences [of the recall] will be perceptual, but it does add to the embarrassment in a program whose glitches have already been well publicized.”
The weakened potency of the vaccine doses was identified by Sanofi Pasteur during routine quality assurance testing, and the company has not yet determined the cause.
Representatives from the company were not immediately available for comment.