The British government said on Friday that it has asked its independent medicines regulator to study Pfizer BioNTech's coronavirus vaccine with a view to an imminent roll-out.
If approval is given, mass vaccination could start in December.
"I can confirm that the government has formally asked the Medicines and Healthcare products Regulatory Agency to assess the Pfizer BioNTech vaccine for its suitability," Health Secretary Matt Hancock told a news conference.
"If a vaccine is approved, it will, of course, be available across the UK, from our NHS (National Health Service), free at the point of delivery according to need, not ability to pay."
Britain, which has seen nearly 54,000 deaths from 1.4 million cases in the outbreak, has ordered 40 million doses of the Pfizer jab and expects 10 million doses by the end of the year.
Hancock said if approval was given, the health service would be ready to start a mass vaccination programme next month.