A Protocol of National Mixed-Methods Assessment of Childhood and Maternal Immunization

Accurate measurement of routine immunization coverage is essential for detecting immunity gaps, guiding programmatic responses, and supporting equitable vaccine delivery. Iran's Expanded Programme on Immunization has achieved high coverage, but administrative estimates can mask some disparities. The aim of this protocol is to evaluate coverage among children under 3 years old and mothers who have given birth within the last 12 months.

We will conduct a national, cross-sectional, mixed-methods survey on vaccination coverage across all 31 provinces of Iran. A multistage, stratified cluster design will target about 9200 children aged 0-35 months (1325 clusters) and 2109 mothers who delivered in the past 12 months (211 clusters), with oversampling of smaller strata and an allocated proportion for non-Iranian residents. Vaccination status will be verified preferentially from home-based records and electronic registries, supplemented by caregiver recall. Digital data capture and photographed records will be used alongside supervisory quality checks. Quantitative analyses will apply complex survey weighting to estimate coverage, dropout, timeliness, and missed opportunities. Also, thematic analysis of 30-40 in-depth interviews will show determinants of vaccination.

This manuscript describes the protocol for a national mixed-methods study. No empirical results are presented.

The findings from this mixed-methods study will deliver high-quality, disaggregated evidence on immunization coverage and its drivers in Iran, enabling policymakers and programme managers to design and implement targeted interventions to close equity gaps and support sustained uptake of both established and newly introduced vaccines.