Q&A for parents: recall of some batches of children’s 2009 H1N1 flu vaccine:

December 18, 2009, 5:00 PM ET

What vaccine is being recalled?

Some batches (also called "lots") of 2009 H1N1 flu vaccine made especially for children aged 6—35 months old are being recalled. Doctors or others who may have this vaccine are being asked to send any unused vaccine back to the manufacturer. The lots were made by Sanofi Pasteur and are in pre-filled, single-shot packages.

Why is it being recalled?

Vaccines are tested both before and after they are sent out to be used. During a routine stability check, some of the lots of vaccine were found to have fallen below specific requirements for strength (or potency).  This means that the amount of active ingredient in the vaccine that prompt the body to develop immunity had decreased.  However, the decrease was small and should not affect the immune response of children that received the reduced potency vaccine.

This recall is not related to the safety of the vaccines.  There is no safety issue with any of the recalled lots.

What if my child received this vaccine? Does he or she need to be vaccinated again?

Your child does not need to be re-vaccinated. The dose he or she got counts as a full dose. If he or she is less than 10 years old, and it was the first dose that the child got, then he or she needs the regular second dose to complete the normal two-dose series for children in this age group. The two doses should be given at least 28 days apart.

If your child got a second dose using this vaccine, he or she is considered adequately vaccinated. There is no need for them to get another dose. The strength of the vaccine was only slightly less than the acceptable standard, will be enough to get a full immune response. Your child’s immune system will still make antibodies (protection) against H1N1 influenza virus. This is true even if both shots came from a recalled lot. With the coverage of two shots, children will make the immune response they need.

What testing was done on this vaccine before it was shipped to doctors?

Before the vaccine was shipped, it was rigorously tested for safety, purity, and potency (strength), and met all the requirements. As required by the Food and Drug Administration (FDA), vaccine manufacturers keep samples of all vaccines for periodic testing at least until the expiration date. This ongoing testing helps make sure that the supply of vaccines stays safe and effective.

Where was this vaccine distributed? How will I know if my child got this vaccine?

A. The vaccine was shipped to doctors throughout the U.S. The manufacturer is working with doctors and others who give vaccines to make sure that the people who give the vaccines stop using those lots.

You do not need to call your pediatrician or health department to find out if your child got this vaccine. You do not need to take further action, unless your child needs his or her second dose of 2009 H1N1 vaccine. Your child is still considered vaccinated even if vaccinated with vaccine from a recalled lot.

If my child hasn’t been vaccinated yet, what are the options now?

The vaccine that was recalled was packaged in single-dose preservative-free vials. There are other options to vaccinate children aged 6 months through 35 months. Some parents have been concerned about using preservative-free vaccine. This recall does completely reduce the supply of the amount of preservative-free vaccine that is available for children under two.

However, another company makes injectable vaccine for this age group, including vaccine in multi-dose vials that contain traces of preservative (including thimerosal) to prevent contamination from bacteria or fungus. This vaccine is safe for children older than six months. It has been given to thousands of children safely.

For healthy children 24 months (2 years) and older, the nasal spray vaccine is also available and safe. It does not contain any preservatives. Children who have a history of wheezing, asthma, or a medical condition such as diabetes, should only receive the shot, not the nasal spray. If you have questions about what kind of vaccine your child can get, talk to your child’s doctor or nurse.
For more information about preservatives and vaccine safety, click here: "General Questions and Answers on Thimerosal"

Are any of the other children’s or adult 2009 H1N1 vaccines being recalled?

No. No other vaccine is affected by this recall.

After a vaccine is distributed, does it continue to be watched?

Once a vaccine is in use, CDC and FDA monitor any adverse events (health problems after vaccination) through multiple safety systems. To find out more, please visit "Why it's Important to Monitor Vaccine Safety"