Improving vaccination coverage among 24-month-old children in the ASL Napoli 3 Sud: a M.A.S.T.E.R. approach to transformation, evaluation and strategic redesign

Background: Pediatric vaccination coverage is a key indicator of primary prevention and collective protection. Indicator P01C of the New Guarantee System measures coverage among 24-month-old children for the complete primary series and is nationally monitored within the Essential Levels of Care for collective prevention. In ASL Napoli 3 Sud, P01C coverage decreased from 94.57% in 2022 to 92.75% in 2023, revealing organizational, informational, and operational weaknesses. Objective: This study describes the use of M.A.S.T.E.R. (Methodological Approach for Strategic Transformation, Evaluation, and Redesign) as an organizational framework to analyze the decline in P01C coverage, coordinate a multi-component improvement programme, and support monitoring. Methods: This before-and-after quality improvement project was conducted as an implementation-oriented evaluation within a pediatric vaccination service. The period was 2022-2024: 2022 was the historical reference, 2023 the pre-intervention year, and 2024 the implementation/post-intervention assessment year. M.A.S.T.E.R. is a pre-existing QI framework combining Lean Management, DMAIC, PDCA/PDSA, and A3 thinking. The programme included standardized recalls, digital calendars, dashboards, staff training, data cleansing and integration, logistics review, temporary staffing support, and collaboration with Primary Care Pediatricians. Annual P01C coverage was summarized descriptively using aggregate percentages and absolute/relative changes. Results: Critical issues concerned active outreach, cohort tracking, data integration, Sinfonia updates, pediatrician coordination, vaccine logistics, and district variability. In 2024, P01C coverage returned to 94.57%, matching 2022 but remaining below national benchmark of >95%. Change from 2023 was +1.82 percentage points (+1.96%), indicating restoration of previous performance rather than improvement beyond historical level. Recalls increased from 1,248 to 2,136; rescheduled and completed appointments from 286 to 612; late Sinfonia registrations decreased from 21.4 to 8.6%; pediatrician adherence increased from 54.2 to 87.3%; and vaccine distribution time decreased from 7.4 to 3.1 days. Improved recording completeness and timeliness may have contributed to these differences. Conclusion: A multi-component programme organized through M.A.S.T.E.R. was associated with redesign of the pediatric vaccination process and restoration of P01C coverage to the 2022 level. Further evaluation is needed to assess causality, transferability, and long-term sustainability. Transferability requires further evaluation, contextual adaptation, and prospective monitoring.