Furthermore, we stress that implementation of health security capacities is rarely—if ever—a linear process. In other words, the mere presence of a given capacity does not always translate predictably into a desired health outcome or impact. Conceptualising health systems as complex adaptive systems may offer more insight into the varied pathways by which countries achieve public health goals. Rickles et al37 note, for example, that single events can have long-lasting effects on complex systems (‘history matters’), a phenomenon known as path dependence. Paina and Peters further explicate this point, describing how path dependence can complicate health system evolution, particularly in the context of rapidly changing technology and when diverse stakeholders are involved—as is the case in the global health security space.38 They also highlight the futility of transposing health system innovations from countries where they have succeeded into countries with different political processes, or that have not established the institutions or systems required for said innovations to succeed. This might further explain why countries with similar levels of capacity (as indicated by GHS Index scores) might nevertheless report divergent COVID-19 outcomes.