The research carried out with fourth grade French students (13-14 years old) attending secondary public school in an Educational Priority Area. It deals with the analysis of arguments and of the practice of reasoning. We look at SocioScientific Issues (SSI) as potential opportunities to put authentic and valid knowledge into circulation, but we also recognize that the organisation of debates between students is sometimes tricky for teachers. Hence, we examine an alternative approach: Students productions did not come from a phase of exchanges between them, but from an individual documentary approach. We analyzes how they individually deal with the sensitive and complex question of vaccine hesitation, considering the following paradoxe: The vaccine was compulsory against poliomyelitis diseases that was no longer present in French population in 2021, and the vaccine was not compulsory against the raging epidemic of covid-19 in France at the same time. Our results show under what conditions such a a documentary approach to SSI’s can be fecund: We observe that with an increase in the level of contextualization of knowledge, there is also an increase in the number of students who anticipate counter-arguments. It appears that taking into account of specific contexts (through the examination of particular vaccines in a given region and time) lead students to identify the biological knowledge at the heart of the debates.