Against the background of climate change, which enables infectious diseases to move their frontiers and the increasing global mobility, which make people more exposed to contagion, we as citizens need to relate to this new scenario. A greater number of infectious diseases may also potentially lead to an increased need to use antibiotics and anti-parasitic substances. In view of this, the aim of this study was to identify the health literacy needed in the contemporary world and specify what should be taught in compulsory school. We present the findings of a Delphi study, performed in Sweden, regarding the opinions on contagion among experts in the field. We used Nutbeam's framework of health literacy and related it to Bloom's taxonomy of educational objectives in order to analyse and categorise the experts' responses, which were categorised into six main content themes: contagions, transmission routes, sexually transmitted diseases, hygiene, vaccinations and use of antibiotics and antibiotic resistance. These themes were then divided into the three levels of Nutbeam's framework: functional health literacy, which is about knowledge and understanding, interactive health literacy, which is about developing personal qualities and skills that promote health, and critical health literacy, which is about social and cognitive skills related to analysis and critical reflection. The implications for communication and education are then discussed and what should be taught in compulsory school is identified.