LONDON (AP) — The U.K. on Monday became the first nation in the world to start using the COVID-19 vaccine developed by Oxford University and drugmaker AstraZeneca, ramping up a nationwide inoculation program as rising infection rates are putting an unprecedented strain on British hospitals.

Brian Pinker, an 82-year-old dialysis patient, received the first shot at 7:30 a.m. at Oxford University Hospital.

"The nurses, doctors and staff today have all been brilliant, and I can now really look forward to celebrating my 48th wedding anniversary with my wife, Shirley, later this year," Pinker said in a statement released by the National Health Service.

The rollout of the new vaccine comes at a crucial moment for U.K. authorities, who are battling a surge in infections blamed on a new virus variant that authorities have said is much more contagious. Scotland imposed a lockdown until the end of January amid increasing pressure on officials to tighten restrictions throughout the U.K.

Prime Minister Boris Johnson, who has said tougher measures are imminent, announced a nationwide address at 8 p.m. The UK Parliament will be recalled to sit on Wednesday.

"If you look at the numbers, there's no question we will have to take tougher measures and we will be announcing those in due course," Johnson said while visiting some of the people receiving the Oxford-AstraZeneca vaccine at Chase Farm Hospital in north London.

The U.K. is in the midst of an acute outbreak, recording more than 50,000 new coronavirus infections a day over the past six days. On Sunday, it notched up another 54,990 cases and 454 more virus-related deaths to take its confirmed pandemic death toll total to over 75,000, one of the worst in Europe. Some areas northeast of London have infection rates of over 1,000 cases per 100,000 people.

Scottish leader Nicola Sturgeon says that beginning Tuesday, people in Scotland will be legally required to stay at home except for essential reasons to help ease the pressure on hospitals and intensive care units.

Under the new lockdown rules in Scotland, people can go out for exercise but can only meet one other person from another household. School closures are extended until February except for children of key workers and children under social care.

"I am more concerned about the situation we face now than I have been at any time since March last year," she said

Scotland, which has its own devolved government, has often imposed stricter coronavirus restrictions than those in England throughout the pandemic.

U.K. regulators last week authorized emergency use of the Oxford-AstraZeneca shot, giving public health officials a second vaccine in their medical arsenal. Britain's mass vaccination program began Dec. 8 with the shot developed by New York-based Pfizer and its German partner BioNTech.

Britain has secured the rights to 100 million doses of the Oxford-AstraZeneca vaccine, which is cheaper and easier to use than some of its rivals. In particular, it doesn't require the super-cold storage needed for the Pfizer vaccine.

The new vaccine will be administered at a small number of hospitals for the first few days so authorities can watch out for any adverse reactions. But the NHS said hundreds of new vaccination sites — including local doctors' offices — will open later this week, joining the more than 700 vaccination sites already in operation.

A "massive ramp-up operation" is now underway in the vaccination program, Johnson said. But aspects of Britain's vaccination plans have spurred controversy.

Both vaccines require two shots, and Pfizer had recommended that the second dose be given within 21 days of the first. But The U.K.'s Joint Committee on Vaccination and Immunization said authorities should give the first vaccine dose to as many people as possible, rather than setting aside shots to ensure others receive two doses. It has stretched out the time between the doses from 21 days to within 12 weeks.

While two doses are required to fully protect against COVID-19, both provide high levels of protection after the first dose, the committee said. Making the first dose the priority will "maximize benefits from the vaccination program in the short term," it said.

Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said policymakers are being forced to balance the potential risks of this change against the benefits in the middle of a deadly pandemic.

"We have a crisis situation in the UK with a new variant spreading rapidly, and as has become clear to everyone during 2020, delays cost lives," Evans said. "When resources of doses and people to vaccinate are limited, then vaccinating more people with potentially less efficacy is demonstrably better than a fuller efficacy in only half."

In England alone, 23,557 people were hospitalized with COVID-19 on Saturday. While figures for Northern Ireland, Scotland and Wales haven't been updated in recent days, that's higher than the U.K.-wide peak during the first wave of the pandemic.

The government closed non-essential shops across London and parts of southeast England before Christmas to try to contain the new variant, but health officials say tougher measures are now needed.

Johnson said there were "tough, tough" weeks to come in the fight against COVID-19. More school closures, curfews and the total banning of household mixing could be on the agenda.

While schools in London are already closed due to high infection rates in the capital, students in many parts of the country were returning to in-person classes Monday after the Christmas holidays. Unions representing teachers, however, have called for schools throughout England to remain closed for at least two weeks, with classes shifted to remote learning.

Professor Andrew Pollard, one of the scientists who led development of the Oxford-AstraZeneca vaccine, received his shot on Monday.

"It was an incredibly proud moment for me, to have received the actual vaccine that the University of Oxford and the AstraZeneca teams have worked so hard to make available to the U.K. and the world," he said.

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Associated Press Writer Sylvia Hui contributed

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