Seven mass coronavirus vaccination sites opened across England on Monday as the government races to dose millions of people while a new strain of the disease runs rampant across the country.
The sites include football stadiums and a horse racing course, and are located in cities including Bristol, London, Newcastle and Manchester.
They are to vaccinate thousands per week and several more sites are expected to follow, according to NHS England.
Hospitals and pharmacies are set to begin offering the vaccine later this week, with the government hoping to have doses available for 12 million of England's 56 million population by mid-February, starting with the most vulnerable.
More than 1.2 million people have already been vaccinated in England, since the roll-out began of the Pfizer-BioNTech jab on December 8. Britain has since approved the Oxford-AstraZeneca and Moderna jabs.
"We are mobilising the government, NHS (National Health Service) and the armed forces as part of a massive national effort," said health minister Matt Hancock.
Care home residents, all those aged 70 or above, frontline health workers and clinically extremely vulnerable people are first in line for the vaccines.
Britain is grappling with its worst outbreak of the disease since it hit the country early last year.
The record case rates and daily death toll are being blamed on a new, more transmissible strain, which has piled pressure on the NHS, leading to warnings of shortages of critical care beds.
The state-run NHS risks being overwhelmed and the country is in its third lockdown until at least mid-February, with predictions the restrictions could last even longer.
"The next few weeks are going to be the worst weeks of this pandemic in terms of numbers into the NHS," England's chief medical officer Chris Whitty told BBC television on Monday.
- Double down -
"What we need to do, before the vaccines have had their effect... is we need to really double down" on observing lockdown measures, he added.
Vaccines minister Nadhim Zahawi also urged the public to follow the rules, which some have criticised for not being strict enough.
"In supermarkets, we need to make sure people actually wear masks and follow the one-way system rule," he told Sky News.
"We don't want to go any tougher because this is a pretty tough lockdown, but what we need is people to behave as if they've got the virus so we can bring this virus under control whilst we vaccinate."
Britain on Saturday said it had recorded over three million coronavirus cases since the pandemic began last year, having on Friday reported a record 1,325 deaths over a 24-hour period of people who tested positive for the virus.
The full death toll now stands at more than 80,000, one of the highest in Europe alongside Italy.