LANSING - Sanofi-Aventis SA, the maker of the H1N1 vaccine, is recalling about 800,000 doses of the pediatric H1N1 vaccine because tests found the potency was too weak to effectively protect against the virus. Michigan has received about 17,200 doses of the vaccine, which is for children aged six months to three years old.

Health departments, clinics or private doctors' offices within the City of Detroit or within 38 Michigan counties received the recalled doses. The counties include: Allegan, Alpena, Bay, Berrien, Cass, Cheboygan, Crawford, Delta, Emmet, Grand Traverse, Genesee, Ingham, Isabella, Jackson, Kalamazoo, Kalkaska, Kent, Lake, Lapeer, Leelanau, Livingston, Mackinac, Macomb, Manistee, Mason, Mecosta, Menominee, Monroe, Newaygo, Oakland, Otsego, Saginaw, Schoolcraft, St. Clair, Van Buren, Washtenaw, Wayne and Wexford.

While the antigen content of these doses is now below the specification limit for the product, the Centers for Disease Control and Prevention and the Federal Drug Administration are in agreement that the small decrease in potency is unlikely to result in a clinically significant reduction in immune response among persons who have received the vaccine. For this reason, there is no need to revaccinate persons who have received vaccine from these lots.

Providers are being asked to return any vaccine that remains unused to the manufacturer from the specified lots. The CDC also notes the following:

- There are no safety concerns with these recalled lots of 2009 H1N1 vaccine. All doses successfully passed pre-release testing for purity, potency and safety.

- Only specified batches of the 2009 H1N1 pediatric vaccine for children 6 months to 3 years old in pre-filled syringes are affected.

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

- 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.

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

- Children should receive both doses of 2009 H1N1 vaccine from the same type of vaccine (i.e., both doses as inactivated, injectable; or both doses as live, attenuated, nasal spray vaccine).

- All vaccines are routinely tested for purity, potency and safety prior to release. The four batches 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.

The Michigan Department of Community Health (MDCH) encourages residents to get the H1N1 vaccine as it is available to everyone in the state. In addition to being vaccinated, Michigan residents can help stop the spread of the virus by washing hands thoroughly and often; covering mouths when sneezing or coughing; and staying home from work or school if sick.

For more information on vaccine availability, check the MDCH Web site at www.michigan.gov/MDCH. You can also follow MDCH on Facebook and Twitter by going to the Web site. Also, call your local county health department or 2-1-1 public information hotline. If 2-1-1 doesn't work in your area, you can call 866-561-2500 or 800-552-1183.