Trend in mandatory vaccination coverage in Italy from 2000 to 2021. A joinpoint Regression Analysis

INTRODUCTION: Vaccination is one of the most effective public health interventions, preventing more than 4 million deaths each year. However, the complex and multifactorial phenomenon of vaccine hesitancy has increased over the years, causing a reduction in vaccination coverage (VC) and the resurgence of epidemics from vaccine-preventable diseases (VPD). Moreover, the COVID-19 pandemic had a major impact on the capacity of health systems to continue the delivery of essential health services, including vaccination. In this context, the objective of this study is to analyse the trend of 10 vaccinations in Italy (measles, mumps, rubella, tetanus, diphtheria, pertussis, chickenpox, hemophilus, hepatitis B, and polio), from 2000 to 2021, evaluating the impact of the introduction of the mandatory law in 2017 and the pandemic. METHODS: Data were obtained from the Italian Ministry of Health. The joinpoint regression model was used to estimate changes in vaccination coverage trends for each indicator. It allows estimation of an annual percentage change (APC) in vaccination coverage, reflecting an increase or decrease over time. For each indicator, the presence of a joinpoint expressed significant changes in APC trends. APC was considered significant when p < 0.05. RESULTS: Until 2017, a gradual decline in VC is observed, with values below 95% for all indicators considered. For all indicators analysed, an increase (p < 0.005 for measles and chickenpox) in VC is observed following the mandatory law of 2017. Similarly, a reduction in all values is observed from 2020 (p < 0.005 for Tetanus). CONCLUSIONS: The mandatory law represented an effective intervention, leading to an increase in all VC, which for 6 vaccinations reached a value >95%. On the other hand, the pandemic had a significant impact on the reduction of VC in Italy. It is necessary to plan recovery interventions for children in pandemic-affected cohorts to ensure adequate VC values and avoid epidemics from VPD. KEY MESSAGES: • The mandatory law represented an effective intervention increasing vaccination coverage. • It is necessary to plan recovery interventions for children in pandemic-affected cohorts to ensure adequate vaccination coverage.