Data quality in nominal immunization registries: Lessons from the salvador immunization information system (2014–2024) for strengthening DHIS2-enabled health information systems

Introduction Digital transformation in health requires information systems that produce complete, consistent, and standardized records to support routine data quality analyses. Although District Health Information Software 2 (DHIS2) is a global reference, challenges remain regarding data quality, interoperability, governance, and the translation of information into actionable evidence. In Brazil, the Vida Immunization Information System is analyzed as a local case capable of providing transferable lessons for DHIS2-enabled health information systems. Method : This quantitative, retrospective, and exploratory study analyzed nominal records of the measles-mumps-rubella (MMR) vaccine. The analysis covered three dimensions: (i) volume and temporal trend of records; (ii) data quality and completeness; and (iii) territorial distribution of vaccine administration. Segmented regression (Joinpoint Regression Program) and spatial analysis (QGIS) were applied. Results : Completeness was 100% for sex and date of birth, whereas race/color completeness improved to 85.7% (2024). Valid postal codes (CEP) increased from 82.0% (2017) to 97.7% (2024) after the implementation of automatic CEP filling in 2022, reducing missing and invalid records. Installed service capacity remained stable. Approximately 37.7% of doses were administered outside the district of residence, indicating substantial within the municipality mobility and the analytical potential of nominal records for territorial planning. Conclusion : This case shows that local computerized systems can generate high-quality nominal data and reveal temporal and territorial patterns. The findings mirror challenges observed in DHIS2 ecosystems, highlighting the importance of governance, standardization, and analytical use for strengthening health management.