Life Course Immunization in Japan: A Practice-Oriented Framework for Internal Medicine

Life-course immunization extends vaccination beyond childhood by creating repeated opportunities according to age, disease, immune status, pregnancy, occupation, travel, and social context. This approach is particularly relevant to internal medicine because older adults, patients with chronic diseases, immunocompromised hosts, and adults with incomplete records experience substantial morbidity due to vaccine-preventable diseases. In Japan, adult vaccination remains fragmented due to incomplete records, distinctions between routine and voluntary vaccination, variable municipal subsidies, and limited integration into routine care. This narrative review proposes seven recurrent, non-sequential clinical turning points operationalized through an Assessment-Connection-Documentation workflow: assess need and provide a clear recommendation, connect the patient to an accountable completion pathway, and document and share vaccination history and future plans. The framework is intended as a practical implementation model rather than a vaccination schedule and requires prospective evaluation in clinical practices.