French drugmaker Sanofi-Aventis has recalled 800,000 child doses of swine flu vaccine sold to the US because the preservative-free shots have significantly declined in potency since manufacture. The CDC says anyone already vaccinated with the syringes—intended for children 6 to 25 months—is safe, but doctors should return all unused doses. All other doses on the market for children under 2 years now contain the preservative thimerosal. Studies show it to be safe, though it worries some parents, reports Bloomberg.
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