The COVID-19 pandemic has demonstrated the crucial role of crisis communication in promoting the adoption of risk protective measures, combatting mis/disinformation, and maintaining trust in officials. In a situation of high uncertainty, rapidly evolving conditions, and an excess of mis/disinformation, the COVID-19 pandemic emphasized the need for reliable and effective information from officials. Four interrelated studies were used to explore critical success factors associated with maintaining trust in crisis communications during a pandemic. First, a qualitative systematic review was conducted with 13 studies, resulting in 10 descriptive themes related to maintaining trust during emerging infectious disease. Next, a mixed methods study included: a content analysis of Facebook posts for guiding principles for crisis communication; a sentiment analysis of comments to determine the emotional response; and chi square tests to determine significant differences across sources, guiding principles, and sentiments. Third, a mixed methods study of 33 Canadian influencer crisis messages on Instagram was conducted to: describe the use of behaviour change theory constructs; an engagement analysis; a sentiment analysis; and chi square tests to determine significant differences across variables. Finally, semi-structured interviews were conducted with 12 Canadian adults who were not fully vaccinated against COVID-19 and were thematically analyzed, describing four interrelated themes related to crisis communication and trust. The findings of the research demonstrate how guiding principles for crisis communication that demonstrate trustworthiness and constructs from behaviour change models are not being widely or consistently used in COVID-19 crisis messages. Furthermore, the public’s response to crisis messages on social media is neutral at best but often shows negative emotional response to messaging and low overall engagement with official posts. Interviews with vaccine hesitant individuals also show that the perceived low use of guiding principles is negatively impacting trust and contributing to vaccine hesitancy. Results highlight the need and opportunity for crisis communication to be audience-centred and co-created so that messages reflect the needs and values of various communities, in addition to being evidence-based and rooted in guiding principles and theory to maintain trust.