A leading scientific adviser to the British government said Tuesday he expects several coronavirus vaccines to have been approved by early 2021, allowing life to begin to return to normal.

John Bell, professor of medicine at Oxford University, told lawmakers that Monday's announcement by US pharmaceutical giant Pfizer that its vaccine candidate was effective in treating patients was likely just the start.

Bell, a member of the government's Scientific Advisory Group for Emergencies (SAGE) said the news signalled other leading potential vaccines in late-stage trials could prove similarly effective.

"I wouldn't be surprised if we hit the new year with two or three vaccines all of which could be distributed," he told a parliamentary hearing.

"I'm quite optimistic of getting enough vaccinations done in the first quarter of next year that by spring things will start to look much more normal than they do now."

Bell added he believed there was a 70 to 80 percent chance of that scenario unfolding. 

Pfizer said Monday tests of its vaccine developed with German partner BioNTech involving more than 40,000 people had been 90 percent effective and was a "critical milestone" in the bid to counter the virus.

It is one of 10 in late-stage trials around the world, which have so far shown promising results.

The British government has reserved 40 million doses of the drug, which Bell expects could receive regulatory approval within three weeks.

"We're talking about mid-December I think we should be ready to administer this vaccine," he added.

British Prime Minister Boris Johnson gave the news a cautious welcome on Monday, noting it was still "very, very early days" and vaccinating swathes of the UK population was "still some way off".

Health Secretary Matt Hancock said Tuesday that Britain's state-run National Health Service (NHS) was up to the challenge of delivering any vaccine that gets approved with the help of the armed forces.

"The NHS is absolutely ready to do this," he told the BBC, adding that officials had been told to prepare to start administering the vaccine from early December.

The government plans to prioritise  access to the drug, starting with the "most vulnerable, people living in care homes and of course the staff looking after them, NHS and social care staff and then coming down through the age ranges," he added.

Britain has been one of the world's worst-hit by the global pandemic, with more than 49,000 deaths from 1.2 million positive cases.