This article takes an interest in contemporary forms of vaccine criticism, using the case of the French controversy over the safety of the 2009 pandemic flu vaccine. The focus is placed on the different ways in which the actors who criticized the safety of this vaccine built their critique by comparing it to other vaccines, as well as to other objects, public policies, scandals, and past events. This approach allows us to underline the important differences in the politicization of vaccines, which reflect the diversity of trajectories that led these actors to criticize this vaccine in particular or vaccination more generally. Furthermore, this focus on comparisons enables us to shed light on the importance of issues of scientific credibility for these actors, with the threat of being stigmatized as an “antivaccine” looming constantly.