The UK has become the first country in the world to approve the Covid-19 vaccine from Pfizer and BioNTech, paving the way for vaccination to start next week.
The jab has been shown in studies to be 95 per cent effective and works in all age groups.
Here’s all we know about the potentially ground-breaking vaccine:
How many people can get vaccinated?
The UK has ordered 40 million doses of the vaccine, enough to vaccinate 20m people with two doses, given 21 days apart.
Around 10m doses are expected to be available for use in the UK in the coming weeks for priority groups, including healthcare workers, with 800,000 doses arriving next week.
The Government has secured 40 million doses of the Pfizer/BioNTech vaccine, with 10 million due in the UK by the end of the year.
Patients need two doses, meaning not enough shots have been secured for the entire UK population.
A list of who will receive the vaccine first will be set out later on Wednesday.
Watch: PM and Starmer welcome vaccine approval at PMQs
What type of vaccine is this?
The jab is known as a messenger RNA (mRNA) vaccine.
Conventional vaccines are produced using weakened forms of the virus, but mRNAs use only the virus’s genetic code.
An mRNA vaccine is injected into the body where it enters cells and tells them to create antigens.
These antigens are recognised by the immune system and prepare it to fight coronavirus.
What are the advantages of this type of vaccine?
No actual virus is needed to create an mRNA vaccine. This means the rate at which the vaccine can be produced is dramatically accelerated.
As a result, mRNA vaccines have been hailed as potentially offering a rapid solution to new outbreaks of infectious diseases.
They can also be modified reasonably quickly if, for example, a virus develops mutations and begins to change.
mRNA vaccines are also cheaper to produce than traditional vaccines. But both will play an important role in tackling Covid-19.
The early contenders all have high efficacy rates, but researchers say it is difficult to make direct comparisons because it is not yet known exactly what everyone is measuring in the trials.
Is it safe?
All vaccines undergo rigorous testing and have oversight from experienced regulators.
Researchers reported their trials do not suggest any significant safety concerns.
Some believe mRNA vaccines are safer for the patient as they do not rely on any element of the virus being injected into the body.
mRNA vaccines have been tried and tested in the lab and on animals but the coronavirus vaccine is the first one licensed for use in humans.
The human trials of mRNA vaccines – involving tens of thousands of people – have been going on since early 2020 to show whether it is safe and effective.
Pfizer will continue to collect safety and long-term outcomes data from participants for two years.
How will a vaccine be rolled out?
Work has been going on behind the scenes to ensure that NHS staff are ready to start delivering jabs to the most vulnerable, as well as health and care workers, as a priority.
The NHS Nightingale Hospitals have also been earmarked as sites for mass vaccination clinics – among other uses.
In addition, NHS leaders have said there will be “roving teams” deployed to vaccinate care home residents and workers.
Based on the current information, the vaccines being developed require two doses per patient, with a 21 to 28 day gap between doses.
New regulations allowing more healthcare workers to administer flu and potential Covid-19 vaccines have also been introduced by the Government.
Who will be vaccinated first?
The Joint Committee on Vaccination and Immunisation (JCVI) has examined data on who suffers the worst outcomes from coronavirus and who is at highest risk of death.
Watch: Who will get the vaccine first? Priority list revealed for Pfizer/BioNTech immunisations
Its interim guidance says the order of priority should be:
1. Older adults in a care home and care home workers
2. All those who are 80 years of age and over and health and social care workers
3. All those who are 75 years of age and over
4. All those who are 70 years of age and over and clinically extremely vulnerable individuals, excluding pregnant women and those under 18 years of age
5. All those who are 65 years of age and over
6. Adults aged 18 to 65 years in an at-risk group
7. All those aged 60 and over
8. All those aged 55 and over
9. All those aged 50 and over
What do the vaccines cost?
Pfizer/BioNTech is making its vaccine available not-for-profit.
According to reports, the Moderna vaccine could cost about 38 dollars (£28) per dose and the Pfizer candidate could cost around 20 dollars (£15).
Researchers suggest the Oxford vaccine could be relatively cheap to produce, with some reports indicating it could be about £3 per dose.
AstraZeneca said it will not sell it for a profit, so it can be available to all countries.
However, the details of the deals made by the UK Government have not been made public.
Additional reporting by PA Media.