The European Commission said on Thursday that it has signed a contract with AstraZeneca (LSE:AZN) (NYSE:AZN) (STO:AZN) for the supply of at least 300 million doses of a vaccine against COVID-19, with an option for further 100 million doses.

Through this contract, member states of the European Union will be able to purchase the AstraZeneca vaccine to be distributed on a population-based pro-rata basis. Doses of the vaccine may also be donated to lower and middle income countries or redirected to other European countries.

The contract comes two weeks after the Commission signed an advance purchase agreement with AstraZeneca. It is the EU's first contract with a maker of potential COVID-19 vaccines.

AstraZeneca partnered with the University of Oxford to develop and distribute a potential recombinant adenovirus vaccine aimed at preventing COVID-19 infection. The vaccine candidate is already in large-scale Phase II/III clinical trials after promising results on safety and immunogenicity in Phase I/II.