The UK has approved Pfizer and German partner BioNTech’s vaccine for use and the shot will be available from next week.
Here’s a look at the key questions concerning the rollout:
How does the vaccine work?
Pfizer's 95 per cent effective shot is an mRNA vaccine. Traditional vaccines inject people with a dead or weakened part of a virus so the body produces antibodies to fight it, as it would in a natural infection. But mRNA vaccines differ in that they encourage the body to become its own miniature vaccine factory.
The vaccine, an abbreviation of messenger RNA, delivers genetic instructions that prompt the body to produce virus proteins – without exposing the body to any threat.
Once this happens, the immune system begins to build up protective antibodies to guard against infection.
When will it be available?
The first 800,000 doses will be available in the UK from next week, Health Secretary Matt Hancock said.
The doses will then be rolled out as quickly as they can be made by Pfizer’s factory in Belgium, he said, with “several million” being made available in December and the bulk of the rollout taking place next year.
The UK ordered 40 million doses of the Pfizer vaccine – enough for 20 million people to be vaccinated as it is a two-dose regimen.
Mr Hancock predicted the UK would begin to return to normality in the first half of 2021. "From the spring onwards, things will start to get better," he told BBC Radio 4's Today programme.
Who will receive the vaccine?
Care home residents and staff are officially first in line to receive the shot. However, it may not be possible to deliver the initial batch to care homes given the need to store the vaccine at ultra-cold temperatures.
Therefore, health workers are likely to be among the first to be inoculated because storage of the vials is easiest in hospitals.
When more doses are delivered, the first phase of the rollout will begin.
As part of this phase, the order of groups to be given the vaccine has been announced by the Joint Committee on Vaccination and Immunisation (JCVI):
1. residents in a care home for older adults and their carers
2. everyone aged 80 and over, and frontline health and social care workers
3. everyone aged 75 and over
4. everyone aged 70 and over, and those who are extremely vulnerable clinically
5. everyone aged 65 and over
6. people aged 16 to 64 with underlying health conditions which put them at higher risk of serious disease and death from Covid-19
7. everyone aged 60 and over
8. everyone aged 55 and over
9. everyone aged 50 and over
People in those groups will be called up on a random basis, with contact made by letter. These groups cover 90 to 99 per cent of those at risk of dying from Covid-19, according to the JCVI.
People will be given two doses 21 days apart, with immunity achieved seven days after the second dose.
Who will administer the vaccine in the UK?
The vaccine will first be administered by hospitals, at vaccination centres being set up across the country and at GPs and pharmacists.
The health service is also recruiting up to 300,000 volunteers to help with distribution at the height of the rollout. Firefighters and the Army are also may be called upon to deliver the shots.
How will it be stored?
The Pfizer vaccine needs to be stored at minus 70°C, which presents logistical problems for health officials.
However, under Pfizer’s plan, the doses are stored in special, dry ice packs while they are transported to the UK via plane or lorry.
Once at the vaccination centre, the vials can be kept in a refrigerator at between 2°C and 8°C for up to five days. If taken out of the fridge, the diluted vials have to be used within six hours.
Is the vaccine safe?
The boss of Britain’s health regulator said “no corners have been cut” as she reassured the public the vaccine was safe.
Dr June Raine, head of the Medicines and Healthcare products Regulatory Agency (MHRA), said the vaccine had met all the tests for safety, effectiveness and quality.
She said: “This vaccine has only been approved because those strict tests have been done and complied with.
“Everyone can be assured that no corners have been cut.”
Pfizer reported that a small number of participants in its trials received side effects including fatigue, headaches and muscle pain.
Participants in the trial will continue to be monitored over the coming years, it said.
Peter Openshaw, professor of experimental medicine at Imperial College London, added: “There is absolutely no doubt at all that any risk of receiving the vaccine is far outweighed by the risk of getting Covid.”
Moreover, BioNTech was confident the vaccine could protect against mutations of the virus for at least a year.
How many doses can be rolled out?
Pfizer said it would distribute “as many doses as quickly as we can” and estimated 50 million could be distributed this month.
However, not all the doses are headed for the UK. The US, which has ordered up to 600 million shots in total, could approve the vaccine as early as December 10.
The EU is also expected to make a decision in late December. Pfizer estimates it can produce 1.3 billion doses next year.
How does the Pfizer shot compare with other vaccines?
The Pfizer vaccine needs to be kept at minus 70°C while in storage, which may present headaches for health officials who have to source ultra-cold freezers.
The Moderna vaccine, however, can be stored for up to six months at minus 20°C.
While the AstraZeneca/Oxford vaccine has lower efficacy than the Pfizer and Moderna shots, it is cheaper, easier to store and therefore more practical to distribute to the world than the two rivals.
The AstraZeneca dose has an average 70 per cent effectiveness rate.
The trials showed a regimen of two full doses one month apart was 62 per cent effective, but a half dose followed by another full shot showed 90 per cent.