Polio and measles: Reasons of missed vaccination in Italy, 2015-2017

Background. Also in Italy, a flourishing evidence confirms the recent spread of vaccine hesitancy movements resulting in approximately 4-7% of the paediatric population not immunised every year against polio and approximately 9-15% against measles in the last few years. The aim of this paper is to describe the reasons of polio and measles missed vaccination in Italy, in the period 2015-2017, and to analyse any potential effect of the 2017 mandatory vaccination law. Methods. Number of missed vaccinations in children younger than 24 months, stratified by reason, were collected separately for measles and polio with a regional level of detail. Data were collected using an electronic form developed using Microsoft Excel®. Results. The most frequent reason for missed polio vaccination was "definitive informed dissent" with a mean value 1.5%, followed by "found/contacted, but did not attend the appointment" with a mean value 1.3%. Inversely, "acquired immunity subsequent to previous disease or vaccination performed elsewhere" and "excused in a permanent way for health conditions" were the less frequent with a mean value 0.03% for both. For measles vaccination the reason "found/contacted, but did not attend the appointment" was the most frequent (mean value 3.2%), followed by "definitive informed dissent" (mean value 2.9%). Conclusions. Percentage of missed vaccination showed a remarkable reduction in 2017. This decrease is likely due to the introduction of mandatory vaccination law. In point of fact, "Dissent" decreased for both polio and measles during the study period. While, "Delay" increased during the 3-years. It seems that hesitant parents prefer to postpone vaccinations instead of refusing them. Counselling, parents' empowerment and vaccine education are central to contrast vaccination postponing. Thus, for parents who refuse vaccines ("Dissent"), monitoring the trend is important as well as trying to understand their reasons.