Also further analysis of the contract indicates that "best endeavours" was only applicable until the vaccine was developed. Once the vaccine was developed, then the "best endeavours" clause is no longer admissable.
Mrs von der Leyen said in Friday morning's radio interview.
"'Best effort' was valid while it was still unclear whether they could develop a vaccine. That time is behind us. The vaccine is there.
"AstraZeneca has also explicitly assured us in this contract that no other obligations would prevent the contract from being fulfilled," she said.
https://www.bbc.com/news/world-europe-55852698
It looks like the EU's case might be much stronger than at first thought.