EU Commission chief Ursula von der Leyen said "genuine progress" had been made on several issues "with an outline of a final text", little more than a month before Britain's transition period as a former EU member runs out.
The commission, the EU's executive arm, has agreements with six potential vaccine suppliers and is working on a seventh contract.
The contract provides for the initial purchase of 80 million doses on behalf of all European Union member states, plus an option to request up to a further 80 million doses, to be supplied once a vaccine has proven to be safe and effective against Covid-19.
In a speech to the European Parliament, von der Leyen defended the scheme that would link EU payments to respect for certain rule-of-law criteria as "appropriate", "proportionate" and "necessary".
"Once the vaccine is indeed proven to be safe and effective, every Member State will receive it at the same time, on a pro-rata basis, on the same conditions".
Doses from Moderna would be enough to vaccinate 80 million people as the vaccine is expected to be administered in two doses. "You name it. All this has to be prepared", she warned. The pandemic situation remains serious, "with almost 3,000 deaths a day", von der Leyen admitted. "Hospitals remain under stress, and in some regions some intensive care units are overwhelmed", she said. "But we must learn from the summer and not repeat the same mistakes", von der Leyen said. on Wednesday.
British Prime Minister Boris Johnson has said he won't ask for more time to strike a deal with the European Union, despite the president of its executive, Ursula von der Leyen, saying the 27-nation bloc was preparing for a no-deal Brexit.