ABSTRACT
Introduction: The European Joint Action on Vaccination (EU-JAV) is a European project that aims at spurring long-lasting European cooperation against vaccine-preventable diseases. In the context of the EU-JAV's Work Package 8, the Italian National Institute of Health, in collaboration with the Bambino Gesu Children's Hospital (Rome, Italy), developed a web platform designed to monitor vaccination discourse on the web and on social media. Materials and methods: We collected data on vaccine-related content from Twitter, Reddit, Wikipedia and Google Trends, through validated keyword filters, in Italian, French and Spanish. The platform's analysis layer included two machine learning-based algorithms: the influencer analysis, aimed at identifying the most influential users involved in the vaccine discourse;and the early-signal detection, used to identify new hashtags emerging in the conversation.