The NHS has begun the biggest mass vaccination campaign in its history to protect people against Covid-19.
So far, three vaccines have been approved for use in the UK.
More than 3.2 million people in the UK have now been vaccinated - the large majority with the Pfizer-BioNTech vaccine which was approved in early December.
Who is getting the vaccine first?
Broadly, vaccines are being given to the most vulnerable first, as set out in a list of nine high-priority groups, covering around 25 million people in the UK.
They are thought to represent 90-99% of those at risk of dying from Covid-19.
- Residents in care homes for older adults and their carers
- 80-year-olds and over and frontline health and social care workers
- 75-year-olds and over
- 70-year-olds and over and clinically extremely vulnerable individuals
- 65-year-olds and over
- 16- to 64-year-olds with serious underlying health conditions
- 60-year-olds and over
- 55-year-olds and over
- 50-year-olds and over
Around 45% of people aged over 80 in the UK have now been vaccinated, according to government figures.
Frontline health staff, care home residents and workers as well as the over-80s have been the first to get jabs at designated hospitals hubs, GP surgeries and community sites across the UK.
The Oxford/AstraZeneca vaccine is better suited to protecting people who are housebound and in care homes because it's easier to store and transport.
The aim is to:
- vaccinate every care home resident by the end of January
- everyone over 70, NHS frontline staff, care workers and anyone who is clinically extremely vulnerable by mid-February
- the rest of the priority groups and over 50s after that, possibly by May
The second phase of vaccination will focus on the rest of the population, mainly the under-50s, who are much less likely to be ill with Covid-19.
Teachers, transport workers and the military could be prioritised at that point, but more data on how well the vaccines are working will be needed before that decision is made.
What about the two-dose policy?
All the approved vaccines require two doses to provide the best possible protection.
Initially, the strategy for the Pfizer vaccine was to offer people the second dose 21 days after their initial jab - full immunity starts seven days after the second dose.
But when approval was announced for the Oxford-AstraZeneca vaccine on 30 December, it was also announced that the new priority would be to give as many people a good level of protection with the first shot of either vaccine, rather than providing the required two doses to a smaller number of people in as short a time as possible.
Everyone will still receive their second dose, but this will now be within 12 weeks of their first.
The US regulator and some UK experts have questioned the policy, saying it is premature without more trial evidence, but the UK's regulator, the MHRA, says it is a pragmatic decision that will protect more people.
Can different vaccines be mixed and matched?
The official guidance states that every person should get the same vaccine for both doses.
Dr Mary Ramsay, head of immunisations at Public Health England (PHE), said: "We do not recommend mixing the Covid-19 vaccines - if your first dose is the Pfizer vaccine you should not be given the AstraZeneca vaccine for your second dose and vice versa."
However, in the very rare circumstance in which only one vaccine is available at a vaccination site or it's unknown which product an individual received for their first dose, PHE says a different vaccine could be administered.
But this advice does stress "this option is preferred if the individual is likely to be at immediate high risk or is considered unlikely to attend again".
"There may be extremely rare occasions where the same vaccine is not available, or where it is not known what vaccine the patient received," Dr Ramsay said. "Every effort should be made to give them the same vaccine, but where this is not possible it is better to give a second dose of another vaccine than not at all."
How many vaccine doses are there?
More than 2.5 million people in the UK have now had their first dose of a vaccine in just over three weeks since vaccination began.
The aim is to reach two million vaccinations a week soon, in order to meet the target of giving everyone in the top four priority groups (up to 15 million people) a first dose by mid-February. But this depends on getting a steady supply from the manufacturers and the required quality checks being carried out, which can take weeks.
In total, the UK has ordered 100 million doses of the Oxford-AstraZeneca vaccine and 30 million of the Pfizer vaccine, which will be shared out fairly among the four nations. Another 17 million doses of the Moderna vaccine are expected in the spring.
They will be delivered in batches over the coming weeks and months once they have been quality checked by the regulator, the MHRA.
Where will I get a vaccine?
You'll be invited to book an appointment to get a vaccine as soon as it's your turn, probably by phone or letter.
Vaccinations will take place:
- in hospital hubs for NHS staff, care staff and older patients
- in thousands of GP surgeries to the over-80s initially
- in care homes to workers and residents
- in pharmacies, a small number to start with
- in sports stadiums and conference centres acting as major vaccination hubs for priority groups initially
Around 1,000 vaccination sites are currently in operation, including hospitals and GP surgeries, with each local area having a designated site. A small number of pharmacies are also offering vaccinations, but only if they have the staff and storage facilities to be able to do so.
The NHS is recruiting 30,000 volunteers to help with the rollout, including lifeguards, airline staff and students - who will be trained to give the jabs.
Will everyone be vaccinated?
The eventual aim is that as many people as possible over the age of 18 receive a Covid-19 vaccine.
It won't be compulsory, though - no other vaccines in the UK are - as experts say this wouldn't help create confidence in the vaccine.
The government has so far ordered seven different types of vaccine and expects to receive 367 million doses.
If everyone needs two doses, that would certainly be enough for every adult in the UK.
Which vaccine will I get?
Experts have concluded that both vaccines are very effective, and have not stipulated a preference for either one in any specific population.
What about people with allergies?
Anyone with a previous history of allergic reactions to the ingredients of the vaccine should not receive it, but those with any other allergies such as a food allergy can now have the vaccine.
A severe allergic reaction - known as anaphylaxis - is a very rare side-effect with any vaccine, but it can happen in those at risk. Most people, however, will not be affected in any way.
The medical regulator, the MHRA, says anyone due to receive their vaccine should discuss any medical history of serious allergies with their healthcare professional beforehand.
I'm pregnant - will that affect when I'm vaccinated?
Vaccination with either vaccine should only be considered for pregnant women when the potential benefits outweigh any potential risks - for instance where the risk of exposure to coronavirus is high and cannot be avoided, or where the woman has underlying health conditions that put her at high risk of complications of Covid-19.
Women should discuss the benefits and risks of having the vaccine with their healthcare professional and reach a joint decision based on individual circumstances.
Women who are breastfeeding can be given the vaccine.
There are no specific safety concerns with the vaccines - but they were not tested on pregnant women during the trials.
Pregnant women are likely to be low down the list of priority groups because of their age, and may only be offered a vaccine in the second phase in 2021.
Can I pay to be vaccinated sooner?
No - this vaccine is being rolled out free to people via the NHS.
You can't jump the queue by paying for it, but there should be plenty of vaccine to go round.
Should I leave a gap between getting the flu and Covid vaccines?
If you're eligible for a flu vaccine, you should get it as soon as possible, particularly if you will also be in a high-risk priority group for a Covid jab.
Having both illnesses at once this winter could be dangerous.
At its last meeting, the Joint Committee on Vaccination and Immunisation (JCVI) recommended leaving at least seven days between the vaccines.