In this perspective paper, we argue that the broader economic, political, and geo-strategic considerations leading to a nationalist approach in the development, deployment, and use of COVID-19 vaccines remain largely unexplored in the existing literature. We propose to expand and reframe the current discourse on vaccine nationalism (VN). This involves examining nationalist practices and policies beyond merely securing vaccine access during the global COVID-19 vaccine shortage. We seek to identify the core characteristics of this nationalist approach to COVID-19 vaccines by drawing on existing nationalism literature. We then examine the root causes of vaccine nationalism from three distinctive yet interrelated perspectives, each aimed at uncovering its root causes: national security, technological catch-up, and rising geo-strategic competition in technology and ideology. Notably, our analysis of VN draws extensively on the vaccine-related policies and practices observed in China. By considering these perspectives and their interplay, we contend that a more holistic and nuanced understanding of vaccine nationalism can be achieved.