Background The article questions the popularity of resilience as a concept and its application to health care systems as a main lens for understanding the impact the COVID-19 pandemic on them. Methods It develops a sociological definition following a thorough examination of the various proposed meanings for the term. Subsequently, it proposes a conceptual framework to analyze the vulnerability and sustainability of health care systems as a more comprehensive tool that moves beyond the limitations of resilience. This framework is then applied to evaluate its heuristic value in assessing the resilience strategies adopted in response to the COVID-19 pandemic in five European countries (France, Hungary, Italy, Sweden, and the United Kingdom), considered as problematic ‘sentinel cases’ within their health macro-regions. Adopting the six variables provided by the COVID-19 Health Systems Response Monitor of the European Observatory on Health Systems and Policies, a detailed comparative analysis is conducted. This analysis explores the resilience strategies of these countries in terms of the vulnerability outputs they produced and their consequent effects on the sustainability of their health care systems. Results The results show that the resilience strategies adopted during the pandemic were shaped by the different configurations of health care systems and policy decisions regarding resource mobilization. As such, these strategies produced various vulnerability outputs, resulting in different degrees of risk distribution and sustainability. Conclusions These results are pertinent for understanding that what matters from a sociological point of view is not simply how different health care systems cope with external shocks like a pandemic to retain control over their structure and functions (resilience), but the social consequences produced by their strategies.