Langbecker); Madrid University Carlos III (
Catalan-Matamoros); University of Almeria (
Catalan-Matamoros) In order to avoid having journalistic content that is merely a reproduction of a few sources, it needs to offer a diversity of voices and perspectives. By disseminating quality health-related information, the news media can influence individual and collective decisions on vaccination. Sources are people (speaking on their behalf or as members or representatives of an institution or organisation) who offer information or suggestions to journalists when drafting a news story. From the point of view of agenda-setting theory, sources can play a key role in shaping public opinion on specific content, as well as influencing the approach of a news piece (framing). This study examines information sources on vaccines in the Portuguese press, thus identifying those who guided the topics and discussions on vaccination.