Vaccine maker Sanofi Pasteur ate crow yesterday with its recall of four batches of H1N1 baby shots--800,000 shots in all. It was not clear how many of the vaccines had been administered before the recall went out.

The good news is that the recall has nothing to do with safety, but concerns a small dip in vaccine potency that health officials say is no cause for worry.

All vaccine makers hold back samples of each lot they ship and over the ensuing weeks, test samples to ensure that their potency remains high. At the time of this follow-up testing, the lot samples in question had dropped below a predetermined limit. And, so, the recall.

How might this affect your child's protection against H1N1?

Not at all if your child is age 3 or older or was immunized with either the nasal-spray vaccine or the type of injectable vaccine packaged in multi-dose vials (the type used at most flu-shot clinics).

The recall involved only thimerosal-free baby shots in prefilled syringes.

But even babies and toddlers who received one of the sub-par shots will be fully protected so long as they complete the two-dose immunization regimen recommended for all children under age 10, says Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases. (These two doses are administered approximately one month apart.)

Still want more detail, even lot numbers? Visit the recall answer page set up by the Centers for Disease Control and Prevention.