Be sure you use G-codes when billing Medicare for administering H1N1 influenza (swine flu) shots to your Medicare patients. CMS recently stated they won't accept the new swine flu codes developed by the AMA -- at least, for now.
CMS gives you this guidance on billing the swine flu:
"Billers must report HCPCS code G9141, Influenza A (H1N1) immunization administration (includes the physician counseling the patient/family) to bill for the administration of the vaccine, using diagnosis code V04.81 (influenza). Institutional providers, depending on the provider type, should also use revenue code 771."