LONDON (REUTERS) - Britain began vaccinating its population with Oxford University and AstraZeneca's Covid-19 shot on Monday (Jan 4) in a world first, racing to give protection to the elderly and vulnerable as a new surge of cases threatened to overwhelm hospitals.

Against a darkening backdrop of record daily cases, Britain touted a scientific "triumph" as dialysis patient Brian Pinker, 82, became the first person to get the Oxford/AstraZeneca shot outside of a trial.

"I am so pleased to be getting the Covid vaccine today and really proud that it is one that was invented in Oxford," said Pinker, a retired maintenance manager, just a few hundred metres from where the vaccine was developed.

Britain, grappling with the world's sixth worst death toll and one of the worst economic hits from the Covid crisis, was the first country to roll out the vaccine developed by Pfizer and Germany's BioNTech just under a month ago.

It is prioritising getting a first dose of a vaccine to as many people as possible over giving second doses, despite some doctors and scientists expressing concern.

Two new variants of the coronavirus are complicating the Covid-19 response and Britain has seen a resurgence in cases to new daily highs.

Scientists are not fully confident that Covid-19 vaccines will work on a variant found in South Africa, ITV political editor Robert Peston said, while cases have also been fuelled by a highly transmissible British variant.

The AstraZeneca rollout came as Prime Minister Boris Johnson warned of "tough, tough weeks to come" and said new restrictions for England were forthcoming.

"If you look at the numbers, there's no question that we're going to have to take tougher measures and we'll be announcing those in due course," Johnson said on a visit to see health workers receiving the Oxford vaccine.

More than 75,000 people in the United Kingdom have died from Covid-19 within 28 days of a positive test, and millions in England are already living under the strictest tier of restrictions.

Moving ahead of Johnson, Scottish First Minister Nicola Sturgeon imposed the most stringent lockdown since last spring.

"It is no exaggeration to say that I am more concerned about the situation that we face now than I have been at any time since March," she said.

Triumph for science

Since the rollout of the Pfizer vaccine started on Dec 8, Britain has administered more than a million Covid-19 vaccines - more than the rest of Europe put together, Health Secretary Matt Hancock said, adding it was a triumph of British science.

Johnson's government has secured 100 million doses of the Oxford/AstraZeneca vaccine which can be stored at fridge temperatures between two to eight degrees, making it easier to distribute than the Pfizer shot.

Six hospitals in England are administering the first of around 530,000 doses Britain has ready. The programme will be expanded to hundreds of other British sites in coming days, and the government hopes it will deliver tens of millions of doses within months.

The US Centres for Disease Control and Prevention said it had administered 4.2 million first doses of Covid-19 vaccines as of Saturday morning and distributed 13.07 million doses.

More than a tenth of Israel's population have had a vaccine and it and is now administering more than 150,000 doses a day.

Germany and Denmark are looking into the possibility of delaying administering a second dose of the Pfizer vaccine to make scarce supplies go further, after a similar move by Britain last week.

Britain became the first Western country to approve and roll out a Covid-19 vaccine, although it is months behind Russia and China which have inoculating their citizens for months.

Others have taken a longer and more cautious approach. Several different vaccines are still undergoing late-stage trials.

India approved the Oxford/AstraZeneca vaccine on Sunday for emergency use.

Andrew Pollard, the head of the Oxford Vaccine Group, was among those to receive the vaccine on Monday.

"We are at the point of being overwhelmed by this disease," he told BBC TV.

"I think it (the vaccine) gives us a bit of hope, but I think we've got some tough weeks ahead."