A pandemic calls for behaviour-change communication: the ethical aim is to have the receiver voluntarily adopt cooperative actions for the wider good of the community. In the case of superdiverse cites, this entails significant translation and mediation across languages and media, since cooperative actions are to no avail if they do not occur in all sections of society. Messages thus have to attract high degrees of trustworthiness. Social media are sites of particular turbulence in this respect for several reasons: (1) They are privileged media for the circulation of dissent; (2) social-media users have high indices of media-comparison behaviour, judging information on one medium in terms of another, thus exhibiting low levels of initial trust; and (3) linguistically diverse communities have electronic media in their first language coming from outside the immediate community, potentially entering into conflict with officially generated and translated information. Here we look at social media use in Melbourne in order to identify instances of trust and distrust in translated pandemic information across several media. We assess the consequences for cooperative behaviour.