20,000 of weaker H1N1 doses came to S.C.; slight potency loss not enough to require another shot

Hundreds of thousands of H1N1 flu shots for children have been recalled because tests indicate the vaccine lost some strength, government health officials said.

The 800,000 shots, made by Sanofi Pasteur, were distributed across the country last month and most have already been used, according to the U.S. Centers for Disease Control and Prevention. The pre-filled syringes were for young children 6 months to 35 months old.

Of the 1.4 million doses of vaccine South Carolina has gotten so far, about 20,550 were from the recalled lots, said Thom Berry, spokesman for the state Department of Health and Environmental Control.

They were used all over the state at DHEC clinics and by private health care providers, he said.

"We did receive a little out of each of the four lots, and we're checking now to see within our own inventory if we have any of it and if so, will send it back," he said. "And we have sent out a notice to providers around the state so they can check their supplies to see if they have any."

There is nothing else for DHEC to do, he said.

Dr. 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.

Young children are supposed to get two doses, spaced about a month apart. Health officials don't think children need to get vaccinated again, even if they got two doses from the recalled lots, said Schuchat.

Swine 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.