Have you noticed that some H1N1 influenza vaccines have an extra long expiration date? Sanofi Pasteur multi-dose vials, for example, have expiration dates into next year, 2011, as compared to the typical June 30th expiration date for seasonal flu vaccines, according the CDC’s new FAQ, 2009 H1N1 Influenza Vaccine with Long-Dated Expiration Questions and Answers. 
The extended expiration date of the monovalent vaccine is to accommodate a possible “third wave” of H1N1 activity through spring and summer of 2010, and even into early fall 2010 when the 2010-11 trivalent influenza vaccine is not yet available, says the FAQ. But that means longer than usual storage considerations and that raises questions which the FAQ addresses.
Also, for general guidance on the basics of vaccine storage and handling, see the checklist under the vaccination safety heading on the Tools page .