The EU's first vaccinations against COVID-19 could take place in the first quarter of 2021, according to a European health chief.
Andrea Ammon, director of the European Center for Disease Control (ECDC), said such a possibility was an "optimistic" scenario.
Her comments come after Pfizer and BioNTech said their potential vaccine had been found to be more than 90% effective.
The companies expect to apply for authorisation for the vaccine to the US Food and Drug Administration (FDA) before the end of the month.
Brussels will sign a deal to secure up to 300 million doses of BioNTech and Pfizer's experimental coronavirus vaccine.
“This is the most promising vaccine so far,” said Ursula von der Leyen, the president of the European Commission, said the EU’s executive arm. “Once this vaccine becomes available, our plan is to deploy it quickly, everywhere in Europe.”
The European Commission had already secured three other deals with pharmaceutical companies allowing its 27 member states to buy nearly one billion doses of a potential coronavirus vaccine.
“And more will come. Because we need to have a broad portfolio of vaccines based on different technologies,” von der Leyen said. “We have already started working with member states to prepare national vaccination campaigns. We are almost there. In the meantime, let us be prudent, and stay safe.”
The commission said once a vaccine is ready, member states should have access to it at the same time, and give priority to groups including healthcare workers and people over 60 years, as well as people with health conditions making them more vulnerable.
Stella Kyriakides, the EU commissioner for health, was more cautious on a COVID-19 vaccine despite admitting "hope is there".
"Even when we have a safe and effective vaccine, it will not be the panacea that will make COVID-19 disappear in a day," she warned.
In conjunction with the national authorities, the ECDC is currently developing the rules to define the priority groups for access.
"In general, these are vulnerable populations and health workers. But we are trying to define it better because these groups are still quite numerous," said Ammon.
According to the latest ECDC score, all EU countries except Finland and Estonia, as well as the UK, are "very concerned" about their epidemic situation.