AstraZeneca recently announced that it would reduce the supply of its COVID-19 vaccine to the European Union in the first quarter of 2021 to 31 million doses. Questions have therefore arisen as to what extent AstraZeneca is under a contractual obligation to supply the European Union with the initially planned 80 million doses, and what role its UK manufacturing sites should play in this regard. To answer these questions, this article examines the parties' rights and obligations under Belgian law.