Moral panics are moments of intense and widespread public concern about a specific group, whose behaviour is deemed a moral threat to the collective. We examined public health guidelines in the first months of the COVID-19 pandemic in Canadian newspaper editorials, columns and letters to the editor, to evaluate how perceived threats to public interests were expressed and amplified through claims-making processes. Normalization of infection control behaviours has led to a moral panic about lack of compliance with preventive measures, which is expressed in opinion discourse. Following public health guidelines was construed as a moral imperative and a civic duty, while those who failed to comply with these guidelines were stigmatized, shamed as "covidiots," and discursively constructed as a threat to public health and moral order. Unlike other moral panics in which there is social consensus about what needs to be done, Canadian commentators presented a variety of possible solutions, opening a debate around infection surveillance, privacy, trust, and punishment. Public health communication messaging needs to be clear, to both facilitate compliance and provide the material conditions necessary to promote infection prevention behaviour, and reduce the stigmatization of certain groups and hostile reactions towards them.