The European Union is about to sign a contract for millions of doses of the Covid-19 vaccine being developed by Pfizer and BioNTech.

The two companies said their experimental vaccine was more than 90% effective, in what could be a major victory in the fight against the coronavirus pandemic.

The European Commission, which is negotiating with vaccine makers on behalf of EU states, said in September it had concluded exploratory talks with US pharmaceutical giant Pfizer and its German partner BioNTech over the supply up to 300 million doses of their potential Covid-19 shot.

However, a deal has not been announced yet.

"According to my information, the respective contract is about to be signed," said Peter Liese, the EU politician who leads on health matters for the largest grouping in the European Parliament.

"There is an agreement that Europeans will be provided with hundreds of millions of vaccines," he added in an emailed statement.

A spokesman for the Commission declined to comment on whether Pfizer's announcement on the efficacy of its vaccine would speed up the signature of a supply deal.

The Commission has said previously that the 27 EU states could also have an option to order another 100 million doses of the Pfizer/BioNTech vaccine.

The EU has already signed supply deals with AstraZeneca, Sanofi and Johnson & Johnson for their potential Covid-19 shots.

The United States, Japan and Britain have already announced supply deals with Pfizer/BioNTech.

Data on the Pfizer/BioNTech vaccine have been assessed since early October by the EU drug regulator, the European Medicines Agency (EMA), under an extraordinary rolling review meant to speed up the possible approval of the shot.

The EMA said in, an email to Reuters today, it had not received the latest results from large-scale trials, but it had already evaluated non-clinical data.

It added that it was currently assessing a second batch of data on the quality of the vaccine, including those related to its ingredients and the way it is produced.

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Protection in patients was achieved seven days after the second of two doses, and 28 days after the first, according to preliminary findings on the Pfizer and BioNTech vaccine.

"The first set of results from our Phase 3 Covid-19 vaccine trial provides the initial evidence of our vaccine's ability to prevent Covid-19," Pfizer chairman and CEO Albert Bourla said in a statement.

"We are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis.

"We are reaching this critical milestone in our vaccine development programme at a time when the world needs it most."

Across much of the globe, Covid-19 infections rates are soaring to record highs, with hospital intensive care units filling up and death tolls mounting as well.

Based on supply projections, the companies said they expect to supply up to 50 million vaccine doses globally in 2020, and up to 1.3 billion doses in 2021.

Phase 3 of vaccine trials is when the drug is given to thousands of people and tested for efficacy and safety.

When it is approved and licensed, a vaccine will enter into Phase 4 ongoing studies.

European stock markets soared as much as 7% following the successful vaccine trials.

Medical experts reacted to the news with cautious optimism, with one professor saying it appeared "very encouraging".

Pfizer last week announced it was creating about 300 jobs at its manufacturing sites in Grange Castle in Co Dublin, Newbridge in Co Kildare and Ringaskiddy in Co Cork.

The US drugs company said it is investing about €300m in its Irish operations to support the further development of the three sites.

The coronavirus vaccine breakthrough comes as a leading public health specialist warned that if a new strain of Covid-19 in mink in Denmark becomes dominant, a lot of the work done to date with vaccines will be "for nothing" and their effectiveness will be reduced.

Dr Anne Moore, a senior lecturer in the UCC school of biochemistry and cell biology, said the Pfizer/BioNTech announcement is "really significant".

Speaking on RTÉ's News at One, she described it as "the first breakthrough" in relation to a vaccine that can protect against SARS Covid-2 infection.

She said this trial has so far immunised 43,000 people, including those who received the vaccine and those who got a placebo.

It is an interim analysis, she said, which means they have looked very early on at a small cohort of people who have been diagnosed as Covid positive.

"So this actually is only looking at 94 individuals, not the whole 43,000," Dr Moore said. "That would be very difficult in such a short space of time."

She said that in those 94 cases of Covid-19, there were 90% fewer infections in the vaccinated population.

"Nine or ten of the infected are vaccinated and the other 80 plus people are in the placebo arm of the trial. So it is an interim analysis but it is very, very positive news.

"It does show that there are significantly fewer cases when you're vaccinated. This is seven days after the second immunisation of these individuals, so we do need to see how long that can protect for, but it is a really significant finding."

Pfizer will spend the next month or two following up on all of those who were vaccinated, Dr Moore said, and will then apply for an 'Emergency Use Authorisation' so they can get a licence to distribute and sell the vaccine.

"If there are no major safety signals for the following two months then there will be a vaccine licence for Covid-19 by the end of the year," she said.

"They have 50 million doses ready to go at the moment and a billion ready to go next year. It's a really positive breakthrough today."

Dr Moore said there are at least half a dozen companies "on the same track".

"So hopefully, we will have multiple vaccines that will be licensed, maybe one more by the end of the year. Hopefully another few by spring 2021."