Britain on Wednesday became the first country to approve a Covid-19 vaccine for general use, announcing a rollout of Pfizer-BioNTech's jab from next week in a historic advance for humanity's fightback against the coronavirus.

"It's the protection of vaccines that will ultimately allow us to reclaim our lives and get the economy moving again," Prime Minister Boris Johnson said after the approval by the UK's independent medicines regulator.

But he urged the public to remain cautious on the day that England exited a four-week lockdown and re-imposed regional curbs.

Health secretary Matt Hancock said that starting with care home residents and health and care staff, Britain's National Health Service will begin with 800,000 doses "early next week" and ramp up to "millions" of inoculations by the end of the year.

"Help is on its way," he told BBC radio. "We can see the dawn in the distance but we have to get through to the morning," Hancock added, underscoring the appeal for the public to continue adhering to social restrictions.

England's chief medical officer, Chris Whitty, also welcomed the "excellent news" but stressed: "It will take until spring until the vulnerable population who wish to are fully vaccinated. We can't lower our guard yet."

The breakthrough will encourage hopes the world can finally get back on course in 2021 after a year of traumatic losses, both human and economic.

The novel coronavirus has killed nearly 1.5 million people since the outbreak emerged in China 12 months ago. At least 63 million cases have been registered.

'Science will win'

Pfizer chief executive Albert Bourla said the certification by the UK's Medicines and Healthcare products Regulatory Agency (MHRA) was a "historic moment in the fight against Covid-19".

"This authorisation is a goal we have been working toward since we first declared that science will win, and we applaud the MHRA for their ability to conduct a careful assessment and take timely action to help protect the people of the UK," he said.

US giant Pfizer and German newcomer BioNTech added that they expected further regulatory decisions from other countries "in the coming days and weeks".

The United States and Europe on Tuesday fleshed out plans to administer Covid-19 vaccines as soon as they gain approval, with a US panel recommending that health care workers and nursing home residents be given top priority.

Other vaccines expected to come on stream soon include ones from Moderna and AstraZeneca/Oxford University, which has strong backing from the UK government.

Scientists also acclaimed the UK news but cautioned that logistical challenges remained. The Pfizer-BioNTech jab has to be stored at around -70 degrees Celsius (-94 degrees Fahrenheit), requiring specialist freezers.

"It's not easy but we've got those plans in place," Hancock said.

Campaigners and governments have stepped up calls to ensure poorer countries enjoy equal access to successful vaccines.

The AstraZeneca/Oxford University candidate can be kept in regular refrigerators and is being offered at cost price, but is undergoing further data analysis after questions were raised over the effectiveness of its dosage regime.

The Pfizer-BioNTech and Moderna vaccines have both shown effectiveness against the coronavirus of around 95 percent. Both are based on new mRNA technology.

The mRNA (messenger ribonucleic acid) is used to deliver genetic material to the body that makes human cells create a protein from the virus. This trains the immune system to be ready to attack if it encounters the SARS-CoV-2 coronavirus.

Around 40 percent of US deaths have come from among the country's 24 million care workers and nursing home residents.

The country has the world's highest coronavirus toll, while Britain has the highest toll in Europe.

The European Medicines Agency said it would hold an extraordinary meeting on December 29 "at the latest" to consider emergency approval for the vaccine developed by BioNTech and Pfizer.

'Hold our nerve'

After months of "rigorous" clinical trials and thorough analysis of the Pfizer-BioNTech data, the MHRA "concluded that the vaccine has met its strict standards of safety, quality and effectiveness", the UK health ministry said in a statement.

The announcement came as England exited its month-long coronavirus lockdown, but most of the country remained under restrictions as a new regional system for cutting infection rates kicked in.

Prime Minister Johnson, a Covid survivor, succeeded in winning a vote on the measures in parliament late Tuesday, despite significant opposition within his own Conservative ranks which underlined growing fatigue around the world with curbs.

"All we need to do now is to hold our nerve until these vaccines are indeed in our grasp and indeed being injected into our arms," he told lawmakers before the vote.

Until then "we cannot afford to relax, especially during the cold months of winter", he warned.

Russia was the first country to announce a successful vaccine candidate, dubbed Sputnik V, and has begun a mass coronavirus vaccination campaign for its military. But the drug has not undergone Western clinical trials.