December 15, 2009, 9:00 AM ET

The health district has completed its review of vaccine shipments and has confirmed we did not receive or distribute any of the pediatric doses subject to the voluntary recall.

Please note, the recall is not related to a safety issue. The health district does record lot numbers for each dose of vaccine administered and has the ability to notify clients directly if necessary.

Why are some lots of pediatric H1N1 vaccine manufactured by Sanofi Pasteur in pre-filled syringes being recalled from the market?

As part of its quality assurance program, the manufacturer, Sanofi Pasteur, performs routine, ongoing stability testing of its influenza A (H1N1) vaccine after the vaccine has been shipped to providers. Stability testing means measuring the strength (also called potency) of a vaccine over time. It is performed because sometimes the strength of a vaccine can go down over time.

On December 7, Sanofi Pasteur notified CDC and FDA that the potency in one batch (called a “lot”) of pediatric syringes that had been distributed was later found to have dropped below a pre-specified limit. As a result of this finding, Sanofi Pasteur tested additional lots and found that three other lots that had been distributed also had an antigen content that, while properly filled at the time of manufacturing, was later measured to be below pre-specified limits.

This means that doses from these four vaccine lots no longer meet the manufacturer’s specifications for potency. Sanofi Pasteur will send providers directions for returning any unused vaccine from these lots.

What does potency mean for the H1N1 vaccine?

Potency (or strength) is determined by the measurement of the concentration of the active ingredient (also called antigen) in the H1N1 vaccine.

Are there any concerns about safety of vaccines from these lots?

No. There are no safety concerns with these lots of H1N1 vaccine. All lots successfully passed pre-release testing for purity, potency and safety.

Should infants and children who received vaccines from these lots be revaccinated?

No. The vaccine potency is only slightly below the “specified” range. The vaccine in these lots is still expected to be effective in stimulating a protective response despite this slight reduction in the concentration of antigen. There is no need to re-administer a dose to those who received vaccine from these lots.

However, as is recommended for all 2009 H1N1 vaccines, all children less than 10 years old should get the recommended two doses of H1N1 vaccine approximately a month apart for the optimal immune response. Therefore, children less than 10 years old who have only received one dose of vaccine thus far should still receive a second dose of 2009 H1N1 vaccine.

What action(s) should parents of children who have received vaccine from the recalled lots take?

Parents of children who received vaccine from the recalled lots do not need to take any action, other than to complete the two-dose immunization series if not already completed.

What are the lot numbers affected by this recall?

Vaccine doses with the following lot numbers are included in the recall:

0.25 ml pre-filled syringes, 10-packs (NDC # 49281-650-25, sometimes coded as 49281-0650-25):

• UT023DA
• UT028DA
• UT028CB

0.25 ml pre-filled syringes, 25-packs (NDC # 49281-650-70, sometimes coded as 49281-0650-70):

• UT030CA

How many doses of the pediatric H1N1 vaccine are affected by this recall?

Approximately 800,000 doses of vaccine in these lots were distributed to providers.

Is the potency issue related to this recall isolated to just the pediatric H1N1 vaccine for 6-35 month olds?

The potency problem described here is specific to the four lots of Sanofi Pasteur’s pediatric H1N1 vaccine in 0.25 mL pre-filled syringes. Sanofi Pasteur is investigating what caused the problem.

The same vaccine packaged in other dosing forms, such as pre-filled syringes for older children adults, and multi-dose vials, continues to meet specifications.

This recall does not affect H1N1 vaccine produced by other manufacturers.

Were these lots of vaccine shipped after failing a required test?

No. The lots being recalled passed all quality controls and met all specifications before they were shipped. All vaccines are routinely tested for purity, potency and safety prior to release. The four lots of vaccine met all required specifications at the time of release and shipment to distribution centers.

The vaccine provided in multi-dose vials and the single-dose, 0.5 mL pre-filled syringes for persons 36 months and older continues to meet all specifications.

What is being done to notify providers who received vaccine from the affected lots?

Sanofi Pasteur will send a notification to providers who received doses from any of the four lots of vaccine so that they can return any unused vaccine.

Where were the affected lots of vaccine distributed?

Vaccine from these four lots was distributed throughout the United States.

For U.S. children 6-35 months old, what other options are available currently for vaccination against H1N1 influenza?

For children 6 months of age and older, vaccine is available in multidose vials. The vaccine in multidose vials has not experienced this drop in potency and meets all standards of safety, purity and potency. As with all multidose vials of vaccines, these multidose vials contain a preservative (thimerosal) to prevent potential contamination after the vial is opened.

The standard dose for this preparation in the 6-35 month age group is the same as for the pre-filled syringes, 0.25 mL. For healthy children at least 2 years of age, the nasal spray (live, attenuated influenza vaccine) is also an option. This vaccine is produced in single-units that do not contain thimerosal.

However, it is important that children receive both doses of H1N1 vaccine from the same type of vaccine (both doses as inactivated, injectible, or both doses as live, attenuated, nasal spray vaccine).

Where can I get more information?

Visit the the CDC’s 2009 H1N1 Flu or Vaccine Recalls webpages.