The European Commission and German biotech firm CureVac said that they were in advanced talks for the supply of at least 225 million doses of a potential COVID-19 vaccine to EU states.

CureVac said the talks included an option to supply 180 million additional doses.

EU officials told Reuters that the Commission was also in talks with US biotech firm Moderna and German firm BioNtech, which is developing a vaccine with Pfizer.

CureVac’s approach is based on so-called messenger RNA, pieces of genetic code that prompt human cells to produce therapeutic proteins. Moderna and BionTech are using similar technology.

CureVac said it could start large-scale human trials on its vaccine in the last quarter of this year based on results of its current trials.

The Commission did not disclose financial details but said the funding would be provided through an EU emergency fund, of which around two billion euros ($2.37 billion) can be used to finance advance purchase deals, officials have told Reuters.