The first Covid-19 vaccine is being rolled out across the UK on what has been dubbed “V-Day” by Health Secretary Matt Hancock.
NHS staff have been preparing for the launch, but what does that entail and what can people expect in the next few days?
Here are the key questions around what has been going on behind the scenes and how the vaccination programme will unfold.
When did the Pfizer/BioNTech vaccines arrive and where are they?
The first batch of vaccine vials arrived from Belgium on Thursday.
The UK has ordered 40 million doses of the Pfizer jab, enough to vaccinate 20 million people as people need to receive two doses.
There are 800,000 doses in the first tranche, meaning 400,000 people will be vaccinated initially.
The doses have been stored in undisclosed secure locations to ensure the security of the vaccine and those storing and delivering it.
Are all the vaccines in the right place and ready for rollout?
Doses have already been arriving at vaccine hubs in preparation for the rollout, but it is not known when all 50 hubs in England will receive them as they are starting to administer the jab at different times and deliveries are expected to happen throughout the week.
Pictures showed the arrival of a batch of vaccines at Croydon University Hospital in south London over the weekend, with similar scenes all around the country.
How are the vaccines stored?
The vaccine needs storage temperatures of minus 70C to minus 80C.
Public Health England said it has secured 58 specialised Twin Guard ultra-low temperature freezers which provide storage for approximately five million doses of vaccines that require ultra-low temperature storage.
The freezers are in the UK, fully operational, and located in national storage facilities.
The freezers, which are not portable, each hold about 86,000 doses.
Where will vaccines be administered?
Jabs will be administered at dozens of hospital hubs – with people aged 80 and over, care home workers and NHS workers who are at higher risk being the first to receive the vaccine.
Chris Hopson, chief executive of NHS Providers, said hospitals in England have identified appropriate places to conduct the vaccinations.
He said the ideal place is close to a cark park and separate from any other clinical area where there might be a risk of Covid-19 infection.
Staff will be working out the best arrangements in a socially distanced way and there will be timed slots to minimise queueing.
How are appointments being arranged?
Mr Hopson said staff have been identifying people in the key target groups and lists have been passed to appointment bookers who have been making phone calls to arrange appointments.
He said some hospitals are focusing on people who are due to come in for an outpatient appointment, or those who are currently receiving care in hospital.
Mr Hopson said hospitals are also talking to care homes which have been asked to provide lists of workers.
'We will contact you' says NHS boss:
NHS Chief Executive Simon Stevens advised those in high priority groups to wait for the NHS to get in touch about when they will receive a vaccine.
"We will make contact with you," he said.
What will the appointment involve?
When a patient arrives they will be registered and the vaccine will be administered.
A computer system will issue an email or letter to the patient and their GP saying they have had the vaccine and confirming a follow-up date three weeks later when they will get the second dose.
The jab is typically delivered by an injection in the shoulder.
Should everyone aged 80 and over expect a phone call this week?
No. Mr Hopson said people should not be worried if they do not receive a call or a letter, adding that the vast majority will not be vaccinated until early 2021.
He expects there will be communications in the coming weeks telling people how quickly medical teams are getting through those who are over 80.
Are care home residents not a priority?
They are at the top of the priority list but there are challenges with getting the jab to them.
The Pfizer/BioNTech vaccine needs to be stored at minus 70C before being thawed out and can only be moved four times within that cold chain before being used.
The vaccine boxes containing 975 doses will need to be split so they can be taken to care homes.
Mr Hopson said this will get going in about a week and will be led by primary care networks.
NHS England chief executive Sir Simon Stevens said he was confident vaccinations will be offered in care homes “well before Christmas”.
What plans are in place in Scotland?
Health minister Jeane Freeman said Scotland will receive 8.2% of the 800,000 doses (just over 65,500) in the first delivery secured by the UK, with more to come in the weeks ahead.
She said the doses will go to the 23 commercial-size freezers in acute hospitals around Scotland which can hold the vaccine.
Future plans include mass vaccination centres but that will be further down the line when vaccinators are dealing with younger people.
Other plans include mobile vaccination centres and high street locations where people can go for a jab.
What is happening in Northern Ireland?
Tuesday is the big day in Northern Ireland too with the first dose being administered at a mass vaccination centre at the Royal Victoria Hospital in Belfast.
Among the first recipients are an 800-plus team of vaccinators and there are 25,000 doses in the initial batch.
Healthcare workers will be able to get the vaccine through the rest of December at seven centres across the region.
Two of the facilities are in hospital grounds – at the Ulster Hospital in Dundonald and Belfast’s Royal Victoria – and the rest in leisure centres.
The centres will operate 12 hours a day, seven days a week in an effort to vaccinate 100,000 healthcare and care home staff.
Care home residents and people over 80 are also in the first priority vaccination group, and health officials are continuing to examine ways to administer the vaccine.
How are things looking in Wales?
Frontline NHS and social care staff in Wales were receiving the country’s first coronavirus vaccine from Tuesday.
First Minister Mark Drakeford said he hoped supplies of the vaccine marked a “turning point in the pandemic” that would put Wales “on what is going to be a long path back to normality”.
Health minister Vaughan Gething said Wales will deploy the vaccine in phases, starting with hospital sites and then community settings.
He said the first set of vaccines will be available to just under 19,000 people.
People will be sent appointments with details of where they will receive the vaccination, dependent on where they are on the schedule.
Those receiving a jab will be given a credit card-sized NHS Wales immunisation card which will have the vaccine name, date of immunisation and batch number of each of the doses given.
These will act as a reminder for a second dose and for the type of vaccine, and it will also give information about how to report side effects.