The Centers for Disease Control and Prevention (CDC) has announced an H1N1 (swine flu) vaccine recall. But if you've vaccinated your child, don't worry. The vaccine hasn't been recalled for safety reasons, but for potency reasons. Here's what you need to know.

The CDC is recalling 800,000 of the vaccines because they don't contain enough of an active ingredient, but health officials say the effectiveness is only a little below the optimal level and will still help your child fight off H1N1. But to be sure, they recommend that your child get a booster shot.

The children's H1N1 vaccine recall affects infants and toddlers from six months to 35 months old, who received their shot from a pre-filled syringe without the preservative in it. If your child got the nose spray or a shot from a multi-dose vial, those vaccines are not in question.

Check with your doctor to see if your child's vaccine was affected.

For more information, visit the CDC here.