The agenda and referent subjects and objects of security have widened as both the actors and the themes of national and international security have varied in the Post-Cold War Era. Recently, the epidemics have also been transformed into one of these vital referent objects of security. In fact, not only less-developed and developing countries but also developed countries including great and middle powers would become vulnerable to the pandemics such as in the case of COVID-19. Thus, the European Union (EU) Member States, first and foremost Italy, Spain and France have been profoundly affected by the outbreak of the COVID-19. In fact, the EU must face the implications of this pandemic in a time of existential threats including the Brexit, Euro crisis, rising populism and Euroscepticism. Within this context, this study initially aims to evaluate the vulnerability of the EU to COVID-19, then, the responses to and reflections of the pandemic in terms of the EU���s security in a period when the EU���s solidarity and unity have been already questioned. Eventually, this study discusses the potential impact of COVID-19 as another existential threat on the European integration process.