A Narrative Review of Strengthening Adverse Events Following Immunization Surveillance in Low- and Middle-Income Countries: An Evidence-and-Gap Map and System-Maturity Analysis with India as an in-Depth Case

Adverse event following immunization (AEFIA) surveillance underpins vaccine safety and public trust. WHO's Immunization Agenda 2030 replaced the legacy 10-per-100,000-infants benchmark with a case-based serious-AEFI-per-million indicator. India runs the world's largest immunization program, an information-rich case. To examine AEFI surveillance architecture, reporting performance, frontline readiness, and communication; map density and gaps; and derive transferable low- and middle-income country (LMIC) actions. We conducted a structured narrative review (PubMed, Scopus, IndMED, Google Scholar, WHO IRIS, grey literature; 2000-2026), reported against scale for the assessment of narrative review articles (SANRA). Three layers were applied: a record-linked evidence-and-gap map (EGM), a maturity index, and corpus characterization. Heterogeneity precluded pooling. Governance and causality assessment were most developed; detection, counseling, and digital integration were least mature. A nine-city review found uneven training, registers, and messaging. Perceived AEFI can drive hesitancy, while trials show counseling and mobile reporting to improve knowledge or detection. Validated counseling measures remain scarce. AEFI governance can be structurally sound yet operationally uneven. Priorities: indicator-compatible case-based reporting, measurable counseling quality, competency-based training, and digital integration; mapped gaps are bounded corpus findings, not proof of global absence.