July 2021 marks a pivotal peak in the COVID-19 pandemic, characterized by the rapid propagation of the highly contagious and fatal Delta variant. Intriguingly, data reveals that contrary to expectations, public transport activity not only persisted but escalated during this critical phase. A crucial unanswered question arises: how did individuals' public transport behaviors shift and what drove these changes in response to their fears of COVID-19 and financial instability? This study aims to bridge these gaps in the existing literature by delving into the dynamics of public transport behaviors during the peak of the pandemic and the driving factors behind these changes. We examined transport behaviors from a unique perspective, changes in public transport behaviors over time, by introducing two novel dependent variables: the alteration in individuals’ actual use of public transport and their short-term transport plan. The theoretical model is underpinned by the theory of fear appeal and incorporates two primary independent variables, fears for health and fears for financial conditions. Logistic regression analysis was conducted using survey data collected in the United States between June and July 2021. The results indicated the significant impacts of fears for health and fears for financial conditions on the changes in public transport behaviors. A noteworthy discovery is the fluid and dynamic nature of fears; they are no longer confined to a static state but evolve rapidly over brief periods. This novel facet, denoted as "fear transition," emerges as a key factor in understanding the dynamic transport behaviors amid the pandemic.