| Issue/Objective |
Zero-dose children - those who have not received any routine
immunization - remain a critical public health concern, particularly in low-
and lower-middle-income countries where over 80% of the global zero-dose
population resides. Despite high immunization coverage in some countries,
pockets of zero-dose children persist. Advances in high-resolution spatial
data and geospatial mapping techniques have emerged as precise and effective tools for identifying and addressing immunization gaps. However, no literature has systematically documented the spatial datasets and methods used to identify and characterize zero-dose children. This scoping review synthesizes evidence on spatial datasets, modelling approaches, and critical data gaps in mapping zero-dose children in LLMICs. |
| Methodology/Approach |
Adhering to PRISMA guidelines, we searched six electronic databases
- PubMed, Web of Science, Scopus, Cochrane, Embase, and EBSCOhost-CINAHL - for peer-reviewed articles on spatial modelling of childhood vaccination coverage in LLMICs. We systematically extracted bibliography, study characteristics, covariate types and sources, spatial modelling methods,
and highlighted data and methodological gaps. Articles were synthesized
and thematically summarized focusing on geospatial data, modelling
approaches, and their corresponding gaps. |
| Results |
Of 15,587 articles retrieved, 102 from 68 LLMICs were included, with 70% published between 2021 and 2024, predominantly from Ethiopia (38%), Nigeria (30%), and India (19%). One fifth of studies assessed zero-dose prevalence defined as missing the first dose of diphtheria-tetanus-pertussis-containing vaccine, while the remainder
focused on other childhood vaccines. Covariate data included demographic
(49%), health system (19%), environmental (16%), hard-to-reach (8%), space-related (4%), and infrastructural (4%) factors. Methods comprised clustering and autocorrelation analysis (54%), spatial interpolation (45%), small-area estimation (13%), and machine learning (8%), with 58% of studies applying multiple approaches. Key gaps included inconsistent zero-dose definitions, missing covariates, data inaccuracies, sparse sampling, limited validation, and weak representation of conflict-affected, informal-settlement, and mobile populations. |
| Discussion/Conclusion |
Despite growing availability of spatial data and methods, geospatial identification of zero-dose children remains concentrated in few countries, relies heavily on survey data, uses inconsistent definitions, and rarely translates into actionable, high-resolution, policy-relevant outputs. Addressing these gaps is essential to making zero-dose children visible to health systems and achieving immunization equity globally. |
| Presenters and Affiliations |
Absolomon GASHAIJA Centre for Impact, Innovation and Capacity building for Health Information Systems and Nutrition (CIIC-HIN), Kigali, Rwanda |
