ATLANTA — Hundreds of thousands of H1N1 flu shots for children have been recalled because tests indicate the vaccine doses lost some strength, government health officials said Tuesday.
The shots, made by Sanofi Pasteur, were distributed across the country last month and most have already been used, according to the Centers for Disease Control and Prevention. The 800,000 pre-filled syringes that were recalled are for young children, ages 6 months to nearly 3 years.
Boone County received 400 doses of the recalled H1N1 vaccine, according to the Health Department.
Geni Alexander, spokeswoman for the Columbia/Boone County Department of Public Health and Human Services, said it's important to understand the recall is not the result of a safety concern. People that were administered the recalled doses do not need to be re-vaccinated.
Children under 10 years old need to be vaccinated twice to be fully protected, with the second vaccine administered at least 28 days after the first, according to the Health Department. If children received a recalled vaccine, the second shot ensures they are fully protected.
Not all of the 400 doses had been administered when the recall went into effect. "Some was given at the health department; some was transferred out to providers. As of December 15th, approximately 300 doses of that vaccine had been given in Boone County," according to the Health Department's Web site.
The Health Department has instructed providers to stop offering the affected vaccine, which will be returned to the manufacturer.
Anne Schuchat, a CDC flu expert, stressed that parents don't need to do anything or to worry if their child got one — or even two — of the recalled shots. The vaccine is safe and effective, she said.
The issue is the vaccine's strength. Tests done before the shots were shipped showed that the vaccines were strong enough. But tests done weeks later indicated the strength had fallen slightly below required levels.
Why the potency dropped isn't clear. "That's the $64,000 question," said Len Lavenda, a Sanofi Pasteur spokesman.
Health officials don't think children need to get vaccinated again, even if they got two doses from the recalled lots, Schuchat said.
H1N1 flu vaccine has been available since early October, and since then manufacturers have released about 95 million doses for distribution in the United States.
The recalled shots were made by Sanofi Pasteur, the vaccines division of France-based Sanofi-Aventis Group. The vaccine all tested fine when it was shipped out earlier this fall. But last week, testing of one lot showed that the potency had fallen about 12 percent below the government standard, Lavenda said.
The company found three other lots with diminished strength. It notified government health officials and did a voluntary recall, asking doctors to return any unused doses. The vaccine has been in high demand and the company doesn't expect to see much come back, Lavenda added.
Officials with the Food and Drug Administration, the CDC and the company all said they believe the strength of the recalled doses is still high enough to protect children against the virus. No potency problem has been detected in the same vaccine packaged in other types of syringes or vials, Lavenda said.
Experts have a theory that the problem is specific to the children's pre-filled syringes. For some reason, the antigen — the key vaccine ingredient — might be sticking to the walls of those syringes, said Jesse Goodman, the FDA's deputy commissioner for science and public health.
Another manufacturer, Novartis, in February recalled five lots of seasonal flu vaccine packed in pre-filled syringes under similar circumstances.
Sanofi Pasteur bills itself as the No. 1 manufacturer of flu vaccines in the world. It makes flu vaccine at sites in France and in Pennsylvania.
H1N1 flu was first identified in April. During the first seven months of the pandemic, it has sickened about 50 million Americans and killed about 10,000, according to CDC estimates.
— Missourian reporter Larissa Dalton contributed to this report.