A study in Vaccines analyzes the costs and effectiveness of interventions aimed at reaching zero-dose children—those who have not received any routine vaccinations—in low- and middle-income countries (LMICs). The research evaluates strategies such as mobile outreach, community engagement, and health system strengthening, highlighting their cost-effectiveness in improving immunisation coverage. The findings suggest that tailored, context-specific interventions are essential for reaching underserved populations and reducing inequities. Policymakers and practitioners are encouraged to prioritize investments in these strategies to close immunisation gaps and ensure that zero-dose children are not left behind.