Impact of Italy’s National Vaccine Prevention Plan on Childhood Vaccination: A Time Series Analysis

Abstract Italy has faced significant challenges in achieving optimal vaccination coverage among children, including vaccine hesitancy and regional disparities in healthcare delivery. The National Vaccine Prevention Plan (PNPV) was implemented to address these issues through standardized vaccination protocols and enhanced accessibility. This study aims to assess the impact of PNPV implementation on vaccination coverage rates among children. Data were collected for ten mandatory vaccinations and two recommended ones from official national immunization registries before and after PNPV implementation. An interrupted time series model using Gamma distribution was applied to quantify both immediate and sustained changes in vaccination rates. Statistical significance was determined using 95% confidence intervals. Model adequacy was assessed through diagnostic tests including the Dickey-Fuller test for stationarity, Ljung-Box test for autocorrelation, and Shapiro-Wilk test for normality. For mandatory vaccinations, poliomyelitis, diphtheria, tetanus, and pertussis showed pre-policy declining trends that potentially stabilized post-implementation, though changes were not statistically significant. Hepatitis B coverage remained relatively unchanged. Haemophilus influenzae B, measles, mumps, and rubella demonstrated continuing upward trends without significant policy effects. Notably, varicella initially showed a significant immediate drop in coverage followed by a strong positive trend reversal (β = +0.490, p = 0.0018). Among recommended vaccinations, pneumococcal coverage exhibited a significant immediate increase post-policy (β = +1.105, p = 0.004), while meningococcal showed no significant changes. To enhance PNPV effectiveness, implementing targeted educational campaigns addressing vaccine hesitancy, strengthening regional coordination, establishing real-time digital monitoring systems, and developing vaccine-specific interventions is highly recommended. Key messages • PNPV implementation showed varying effectiveness across different vaccines, with significant positive impacts on pneumococcal coverage and a trend reversal for varicella vaccination. • Targeted educational campaigns and strengthened regional coordination are needed to address persistent vaccination gaps despite national policy implementation.