This document addresses immunizers commonly asked questions about the administration of influenza and pneumococcal vaccines to Medicare and Medicaid patients. It also includes questions and answers that are particularly relevant to the 2011-2012 influenza immunization season. The following information will be useful for immunizers; however, the issues involved in Medicare and Medicaid billing and administration can be complex and may vary from state to state. For additional, detailed information, contact your local fiscal intermediary, AB MAC, carrier (Part B), or the Centers for Medicare & Medicaid Services (CMS). The following sections provide a summary of the current recommendations of the Advisory Committee on Immunization Practices (ACIP) as they relate to immunization; Medicare and Medicaid coverage and payment policy; requirements for mass immunizers and centralized billing; and a brief discussion of managed care. In addition, a list of definitions is included. Background of Medicare Pneumococcal and Influenza Vaccination Benefits.