Toward a Harmonized Immunization Architecture: A Narrative Review of U.S. Guidelines and Implementation Gaps in Immunocompromised Adults

This review proposes a harmonized framework for adult immunization in immunocompromised patients, integrating U.S. CDC, WHO, and IDSA guidelines into a unified, three-phase model: pre-immunization assessment, post-vaccine monitoring, and systems-level reform. The analysis highlights gaps in current protocols, particularly in timing, contraindication assessment, and global harmonization. Recommendations aim to improve physician confidence, patient safety, and international alignment in vaccine delivery.