Abstract for: A Qualitative Approach to Enhance Understanding of Accelerated Vaccine Market Access and Implications for Covid-19 Vaccine Acceptance

The COVID-19 pandemic revealed critical challenges in vaccine development, communication, managing trust, and behavioral responses. These challenges exist beyond the medical side of the pandemic, emphasizing the need of systems based insights for future health preparedness. This study adopts a systems thinking approach to explore how these interconnected factors influenced COVID-19 immunization dynamics in Belgium through a Causal Loop Diagram (CLD). A CLD was developed to map the relationships among risk perception, Non-Pharmaceutical Interventions (NPIs), vaccine production, regulatory processes, public trust, and vaccine hesitancy. Informed by the in-depth stakeholders interviews across Belgium and Europe, the model captures complex interaction and provides a system-level understanding of COVID-19 Immunization System (CIS). The CLD identifies balancing loops like 'NPIs' which reduced the transmission but limited social freedom and 'vaccine acceleration' loops which increased the availability and reduced cases. However, reinforcing loops related to 'vaccine acceleration', 'misinformation', and 'trust erosion' reduced acceptance. Additional pressures from fast-tracked approvals strained regulators. Overall, vaccine acceptance and public's trust on health system which depend on transparent communication, and adequate resourcing over time, unfold as critical points for improving long-term vaccine uptake and pandemic preparedness. The systems map underscores that while accelerated vaccine development was essential, it unintentionally reduced public trust in the absence of adequate transparency and engagement. Similarly, conditional authorizations, although shortened the regulatory timelines, gradually increased pressure on regulatory resources. Therefore, transparent communication, adaptive governance, and anticipatory strategies are essential to build trust and resilience. These findings support the development of more human-centered, integrated approaches to pandemic preparedness and response. Very limited use of AI only to improve vocabulary and choice of words.