In Italy, the vaccination coverage strongly increased from the 31st of December 2017 to the first 6 months of 2018 [
7]. Indeed, the minimum threshold (95% vaccination coverage) recommended by the WHO was reached [
6]. This result can be extrapolated by a medium-term survey carried out to assess the impact of the law on compulsory vaccinations in the cohorts of children born in 2015, 2014 and 2010 [
7]. The Lorenzin’s decree has undoubtedly pushed up the number of compulsory vaccines; however, it would be interesting to understand if the communication campaigns and commitment by the experts on the web had some effects on the opinion regarding the vaccination practice and their possible risks. In recent years, as Italian National Institute of Statistics (ISTAT) official data confirm, the number of Internet users in Italy has increased [
33‐
35]. In 2017, the Italians represented 7.8% of European internet users [
36]. Due to the growth in the number of people who use the WWW to look for health-related information, public health policy-makers should consider the consequences of such use at the population level. For this reason, the analysis of web search trends and social network data could represent an exciting proxy for vaccine hesitancy [
37,
38]. In 2017, YouTube was identified as the most adopted social network in Italy [
6]. Nevertheless, few studies have analysed how people exploit this social network for health purposes and to make decisions on their future behaviour. Indeed, these platforms and their contents have the potential to influence people health behaviours [
20,
39], and thus the influence of vaccine-critical content and increase in using these platforms to share health information is a cause for concern for public health authorities. As also stressed by MacDonald, poor or inappropriate communications can lower the vaccination coverage and contribute to the hesitation of vaccination [
40]. However, the quality of vaccine-related material available online is varied, and internet search engines often bring people to anti-vaccine or low-quality web information; therefore, the potential for misinformation is relevant [
41,
42]. Generally, who use a search engine is likely to focus on the potential risks of the vaccines and thus find anti-vaccination websites. Therefore, widely spread bad contents may contribute to reduce vaccine uptakes and increase the risk of preventable diseases. Hence, at the national level, better communication in the field of vaccination is desirable to counteract the phenomenon of vaccine hesitancy, including the development of digital tools to facilitate progress towards empowerment and changes in citizens’ behaviour. For these reasons, it is vital to stimulate communication campaigns to encourage people healthy lifestyles and develop materials for health education. In fact, communication plays a crucial role in vaccination hesitancy, and thus it is necessary to identify the main communication channels to use resources and strategies that can influence public opinion [
43]. To the best of our knowledge, this is the first study that tries to assess the contents of YouTube videos and their associated sentiment on compulsory vaccination using text mining and sentiment analysis tools. This paper shows that, after the vaccination campaigns and promotion, and also after health ministry change (from 1 June 2018 Giulia Grillo is the Italian health ministry), the topics and sentiment about vaccines on YouTube have changed from 2017 to 2018 (see also Figs.
1 and
2). The vaccines arguments in 2017 on YouTube in Italy were very criticises about their obligatoriness. Most titles expressed dissents and mostly negative sentiment in the linked comments. In 2018, the arguments became less harsh towards vaccination and Lorenzin’s decree, and there was even an inversion of polarity in the sentiment.
The final aim of this paper is to stimulate public authorities to invest in the digital communication for spreading health information, raising awareness among increasingly younger users, and reaching a type of communication that is increasingly popular. Indeed, this kind of information is essential to educate people increasingly inclined to use WWW as a source of information. The competent authorities should invest and apply policies for correct information on the web by financing projects and qualified operators capable of coping with the new digital age.