A Systematic Review and Meta-Analysis on the Effectiveness of Interventions in Reducing Missed Opportunities for Vaccination Among Children Under Age Five.

INTRODUCTION

A knowledge gap exists around which interventions can be implemented to minimise missed opportunities for vaccination (MOVs) in children under age five. Children under age five experience higher rates of MOVs, making them a critical focus for interventions to reduce MOV. This study aims to plot evidence-based interventions reducing MOVs in children under age five.

METHODS

We performed an electronic search without any language restriction for studies indexed between 1 January 1990 and 30 August 2025 in PubMed (Medline), Web of Science, Cochrane Central Register of Controlled Trials, Scopus, CINAHL, and other sources. We included studies highlighting interventions reducing MOVs in children under age five. A meta-analysis was conducted using the random-effects model with risk ratios (RRs) and 95% confidence intervals (CIs). When meta-analysis was not possible, results were reported individually.

RESULTS

Out of 535 papers reviewed via titles and abstracts, 21 were included in the meta-analysis. Overall, education interventions reduced the risk of MOVs by 35% (RR 0.65, 95% CI 0.47 to 0.91). Our results also showed that electronic immunisation registries (EIRs) and alerts were successful in lowering the risk of MOVs by 29% (RR 0.71, 95% CI 0.54 to 0.92). Integrated delivery of health interventions reduced the risk of MOVs by 66% (RR 0.34, 95% CI 0.14 to 0.83). Other interventions that reduced the risk of MOVs included integrating a pharmacist in the under-five vaccination programme (RR 0.43, 95% CI 0.26 to 0.72) and multicomponent interventions (RR 0.62, 95% CI 0.48 to 0.80). Financial incentives (RR 0.87, 95% CI: 0.80, 0.94) and combined vaccines (RR 0.72, 95% CI 0.68 to 0.76) showed a statistically significant MOV reduction. However, our results were graded from very low-to-moderate grade evidence.

CONCLUSIONS

Education interventions, EIRs and alerts, pharmacist inclusion in vaccination programme, integrated delivery of health interventions, multicomponent interventions, combined vaccines, and financial incentives may improve MOVs in children under age five as the evidence was graded from very low to moderate.