Covid-19 vaccine: everything you need to know

Coronavirus frequently asked questions

Updated 20 September 2021

On this page you’ll find answers to frequently asked questions about the Coronavirus (Covid-19) vaccine, and links to further information from trusted, reliable resources.

Looking for quick vaccine facts translated? Visit our Coronavirus vaccine hub page.

What are Covid variants?

All viruses, including SARS-CoV-2, the virus that causes Covid-19, change over time. Most changes have little to no impact on the virus’ properties. However, some changes may affect the virus’ properties, such as how easily it spreads, the associated disease severity, the performance of vaccines, therapeutic medicines, diagnostic tools or other public health and social measures.

Variants can either be ‘Variants of Interest’ (VOI) – where a change to the virus has been detected but it is not known if there will be any impact from this change, or ‘Variants of Concern’ (VOC) – where the changes to the virus make it easier to spread, can cause worse symptoms, or may reduce the effectiveness of vaccines.

What are the names of the Covid variants of concern?

As of June 2021, the Coronavirus variants will be named after the letters of the Greek alphabet to reflect their order of detection instead of their place of first discovery, following an announcement from the World Health Organisation (WHO). The new variant names are listed below.

  • The B.1.1.7 variant, first detected in the UK, Kent, will now be referred to as Alpha.
  • The B.1.351 variant, first detected in South Africa, will now be referred to as Beta.
  • The P.1 variant, first detected in Brazil, will now be referred to as Gamma.
  • The B.1.617.2, first detected in India, will now be referred to as Delta.

Track all Covid variants here.

How do the Covid vaccines work?

The Covid-19 vaccines work in the same way all vaccines do: by sending a signal to our immune system to create the antibodies that will fight the virus. Once your immune system knows how to fight disease, it can protect you in the event of exposure.

Getting a vaccine is a much faster and safer way for your immune system to learn how to create the antibodies required to protect you from a disease, rather than catching the disease or virus itself.

If enough people are vaccinated, it’s harder for the virus to spread to people who are unable to have vaccines. For example, people who are ill or have a weakened immune system. This is called ‘herd immunity’.

See why the vaccination is safe and important.

What are the Covid-19 vaccines?

As of June 2021, four Covid vaccines have been approved for use in the UK:

  1. The Oxford/AstraZeneca vaccine, also known as the Oxford Vaccine, AstraZeneca vaccine or the Vaxzevria Vaccine, was rolled out in December 2020 under a temporary authorisation from the MHRA. It has now been given Conditional Marketing Authorisation.
  2. The Pfizer/BioNTech vaccine, also known as the Pfizer vaccine or BioNTech vaccine, was rolled out in January 2021. It has now been given Conditional Marketing Authorisation.
  3. The Moderna vaccine became available in April 2021 under a Conditional Marketing Authorisation.
  4. The Janssen vaccine (made by Johnson and Johnson), is a single dose vaccine approved in May 2021 under a Conditional Marketing Authorisation, and will become available later in the year.

Other vaccines continue to be developed. Others are in wide use across the globe, but will only be available in the UK if they are required and once they have been thoroughly tested to make sure they are safe and effective.

Learn the difference between the Covid vaccines.

What's in the Covid vaccines? (vaccine ingredients)

The ingredients in the Covid vaccines are very similar to the ingredients found in childhood vaccines, with many commonly found naturally in the human body, such as salt and water. The active vaccine ingredients make up a few thousandths of a gram - this is what actively prepares the body to fight the virus.

What's in the Oxford/AstraZeneca vaccine?

The AstraZeneca vaccine is a viral vector vaccine delivered in two doses (0.5 ml each). It contains a harmless, modified form of a different virus (an Adenovirus) as its active ingredient to deliver the Covid-19 virus proteins for our bodies to recognise and make antibodies against.

The Adenovirus has been altered to stop it from replicating, so it can’t make you unwell. An example of an adenovirus-based vaccine includes one type of BCG vaccine used against tuberculosis. The Oxford/AstraZeneca vaccine does not contain any live virus, so can’t give you Covid-19.

 See the full AstraZeneca Covid vaccine ingredients here.

What's in the Pfizer/BioNTech vaccine?

The Pfizer vaccine is an mRNA vaccine (messenger RNA), delivered in two doses (0.3 ml each). The active ingredient (highly purified single-stranded, 5’-capped messenger RNA ) sends instructions to the body’s cells to make specific viral proteins that can be recognised by the immune system to fight the Covid-19 virus. The Pfizer vaccine does not contain any live virus, so can't give you Covid-19.

See the full Pfizer Covid vaccine ingredients here.

What's in the Moderna vaccine?

The Moderna vaccine works in exactly the same way as the Pfizer vaccine. It's an mRNA vaccine, delivered in two doses (0.5ml each).

See the full Moderna Covid vaccine ingredients here.

What’s in the Janssen vaccine? 

The Janssen vaccine, similar to the Oxford/AstraZeneca vaccine, is an Adenovirus vector vaccine which uses a harmless, modified form of a different virus as its active ingredient to deliver the Covid-19 virus proteins for our bodies to recognise, and make antibodies against.

The Janssen vaccine does not contain any live virus so cannot give you Covid-19. It is delivered in a single dose of 0.5ml. 

See the full Janssen Covid vaccine ingredients here.

The Covid-19 vaccines do not contain chimpanzee cells, foetal tissues, animal products or eggs, and are suitable for vegans and vegetarians.

What are the Covid vaccine side effects?

The most common Covid vaccine side effects include:

  • a sore arm where the needle went in
  • tenderness or aching in the arm
  • tiredness, headaches, general aches and mild flu like symptoms, for some.

Side effect symptoms are generally mild and will usually last 1-2 days. Some people can experience them for longer - up to 1 week.

Because everyone is different, the side effects you might experience (if you get any at all) will depend on which vaccine you receive, whether it’s the first or second dose, and you as an individual.

All Covid-19 vaccines approved for use in the UK with authorisation from the Medicines and Healthcare products Regulatory Agency (MHRA) are considered safe, and will continue to be monitored for safety and effectiveness.

Reports of very rare blood clots
The MHRA has been carrying out a detailed review, and is continuing to investigate, reports of a very rare blood clotting problem affecting a small number of people who have had the Oxford/AstraZeneca vaccine. This condition remains extremely rare and can also occur naturally.

Some of the main causes of blood clots are long periods of inactivity, obesity, smoking and some medical conditions. Clotting problems are also a common complication of Covid-19 infection. More work is still needed to confirm evidence of a possible link between blood clots and the AstraZeneca vaccine. You can find the most up-to-date information here.

The NHS is currently advising that if you are over 30, have other health conditions, or have already had the first dose of AstraZeneca without experiencing any serious side effects, you should still come forward for vaccination when invited. You should always speak to your GP or health provider if you have any concerns. Vaccines are the best way to protect people from getting seriously ill with Covid-19. The benefits of vaccination outweigh potential risks.

For people under 40 without other health conditions, it's currently advised that it's preferable to have another Covid-19 vaccine instead of the Oxford/AstraZeneca vaccine, although you may wish to go ahead with the AZ vaccination after you have considered all the risks and benefits for you. There may also be some other circumstances where people between 30-40, or younger with specific health concerns may be advised to receive the Oxford/AstraZeneca vaccine (based on vaccine availability, risk of illness due to Covid-19, or storage considerations for the vaccine). If you have any concerns, speak to your normal health provider. 

There have also been reports of rare blood clotting disorders associated with the Janssen vaccine in North America. These reports continue to be investigated and assessed, and guidance on the use of the Janssen vaccine will be issued before it is made available within the UK. 


If you experience any of the following from around 4 days to 4 weeks after vaccination you should seek medical advice urgently: 

  • a new, severe headache which is not helped by usual painkillers or is getting worse 
  • an unusual headache which seems worse when lying down or bending over or may be accompanied by 
  • blurred vision, nausea and vomiting 
  • difficulty with your speech 
  • weakness, drowsiness or seizures 
  • new, unexplained pinprick bruising or bleeding 
    shortness of breath, chest pain, leg swelling or persistent abdominal pain. 


Reports of risk of heart inflammation with Pfizer and Moderna vaccines 

There have been extremely rare reports of inflammation of the heart reported after Covid-19 vaccination with Moderna and Pfizer/BioNTech COVID-19 vaccines. Most people who had this recovered following rest and simple treatments.

It is not yet clear if it was caused by the vaccines, and the MHRA is continuing to investigate both the occurrences and any risk factors. They have occurred most frequently in younger males shortly after the second dose of the vaccine.

Anyone who has any of these symptoms within a few days of being vaccinated should seek urgent medical advice:

  • chest pain
  • shortness of breath
  • a fast beating, fluttering or pounding heart (palpitations)


Check for regular updates on Covid vaccine side effects.

What should you do if you're experiencing Covid vaccine side effects?

Mild Covid vaccine side effects are common but not everyone will get them. Side effects usually last 1-3 days, but can last up to 1 week.

If you do experience symptoms, it’s still important to have your second dose. The second dose of the vaccine will give you the best protection against the virus.

If you are experiencing side effects:

  • Rest until you feel better.
  • Take the normal dose of paracetamol (follow the advice on the packaging) to help ease mild symptoms.
  • If your symptoms seem to get worse or if you are concerned, call NHS 111.
  • If you do seek advice from a doctor or nurse, let them know you’ve been vaccinated and show them your vaccination card so that they can assess you properly.

You can also report suspected side effects of vaccines and medicines online through the Yellow Card scheme

Does the Covid vaccine affect fertility?

There is no evidence that the Covid vaccines have any effect on male or female fertility, and there is no need to avoid pregnancy after vaccination.

Can you have the Covid vaccine if you're pregnant or breastfeeding?

If you're pregnant, you should be offered the Covid-19 vaccine when you're eligible for it.

It is currently recommended for you to have the Pfizer/BioNTech or Moderna vaccine if you’re pregnant (because they've been more widely used during pregnancy in other countries, although studies using the AZ vaccine in pregnancy are due to be released shortly).

Speak to your healthcare professional (GP or midwife) before you have the vaccination. They will discuss the benefits and risks with you.

The vaccine cannot give you or your baby Covid-19.You can also have the Covid-19 vaccine if you're breastfeeding.

Read the latest COVID-19 vaccine advice if you're pregnant, may get pregnant or are breastfeeding on GOV.UK

Can children get the Covid vaccines?

All children aged 12 to 15 will be offered a 1st dose of a Covid-19 vaccine. 

Some children may be offered two doses of the vaccine. This includes children aged 12 to 15 with severe neurodisabilities, Down’s syndrome, immunosuppression and multiple or severe learning disabilities. Find more information about Covid-19 vaccine eligibility here.

Most children will be offered a Covid-19 vaccine at school. For children aged 12 to 15 years, consent will be sought by the School Age Immunisation Service (SAIS) provider from the parent or person with parental responsibility in the same way as for any other school vaccination programme. Learn more about the coronavirus vaccination programme for children aged 12 to 15 years.

Parents and guardians will get a letter with information about when the vaccine will be offered.

If your child is eligible for 2 doses of the vaccine, you'll be contacted by your local NHS service or GP to arrange their appointments.

The JCVI recommends that children and young people aged 12 to 17 who live with an immunosuppressed person (someone whose immune system doesn’t work properly, either due to illness or treatment for other conditions such as cancer) should be offered the vaccine. This is to help protect their immunosuppressed household contacts, who are at higher risk of serious illness from Covid-19 and may not generate a full immune response to vaccination.

Following consideration of updated data on hospital admissions and deaths, the JCVI advises that this offer should be expanded to include children aged 12 to 15 with the following:

  • haematological malignancy
  • sickle cell disease
  • type 1 diabetes or
  • congenital heart disease.

See all health conditions listed here.

The JCVI also advises that children with poorly controlled asthma and less common conditions, often due to congenital or metabolic defects where respiratory infections can result in severe illness, should also be offered Covid-19 vaccination. 

Under existing advice, young people aged 16 to 17 with underlying health conditions which put them at higher risk of serious Covid-19 should have already been offered vaccination.

It is also considered reasonable to allow a lead-in time to offer vaccination to young people who are within 3 months of their 18th birthday to ensure good uptake in newly turned 18 year olds.

Children under 12 are at this time unable to be routinely vaccinated against Covid-19. 

Find out more about Covid-19 vaccination in children and young people on

How many people have had the Covid vaccine?

As of September 2021, more than 48,000,000 people in the UK have received their first Covid-19 vaccine dose, and 44,000,000 have had their second dose. Visit Gov.UK for daily updates of the number of people in the UK who have received their Covid vaccine.

All children and adults in the UK (aged 12 and over) are now eligible to receive a Covid vaccine.

Are the Covid vaccines safe?

Yes, the coronavirus vaccines are safe and effective, and will give you the best protection against Covid-19. While they were developed far quicker than the average 8-10 years required for previous vaccines, this is because of the massive effort by researchers, the money invested by governments, and the willingness of volunteers to trial them.

All vaccines approved were rigorously tested before being approved, and have met the strict standards of safety, quality and effectiveness set out by the MHRA.

Vaccines are the most effective way to prevent infectious diseases and save up to 3 million lives worldwide every year. Thanks to vaccine roll-outs in the past, diseases like smallpox, polio and tetanus no longer exist or are very rare.

Read why vaccination is safe and important.

How long does it take for Covid symptoms to appear?

Covid symptoms may appear 2-14 days after exposure to the virus.

The most common Covid symptoms are:

  • a new continuous cough
  • a high temperature
  • a loss of or change in your normal sense of taste or smell.

About 1 in 3 people with Covid-19 do not have symptoms, but can still infect others.

If you, or someone you know might have Covid-19, the advice is to stay at home and arrange to have a Covid test.

Read what to do if you have possible, or confirmed Covid-19.

If you’re concerned about symptoms or are unsure of what to do, get help from NHS 111 online

How long do Covid symptoms last?

Covid symptoms can last for several weeks or months after the infection is gone – this is called ‘long Covid’. However, most people will make a full recovery within 12 weeks.

Common long Covid symptoms include:

  • a high temperature and cough
  • tinnitus, earaches
  • extreme tiredness
  • shortness of breath chest pain or tightness
  • problems with memory and concentration
  • difficulty sleeping (insomnia)
  • heart palpitations and more.

Read more about long Covid symptoms, and what to do if you have it. 

Which vaccine will I get?

Which vaccine you get will mainly depend on availability, but you will only receive a vaccine that has been officially approved. Some people may be advised to have a specific vaccine due to age, medical conditions or allergies. The only vaccines currently available in the UK are Pfizer/BioNTech, Oxford/AstraZeneca and Moderna. 

Which Covid vaccine is best?

Experts agree - the best vaccine is the one that’s offered to you first. All vaccines available in the UK are regularly monitored and have been thoroughly tested. Some people may be advised to have a specific vaccine due to age, medical conditions or allergies.

The Moderna and AstraZeneca Covid vaccines have been approved by the MHRA for individuals 18 years of age and older, whereas the Pfizer Covid vaccine has been authorised for individuals 12 years of age and older.

If you have questions about which vaccine to get, contact 119 or your GP, who can best advise.

Learn how effective the Pfizer vaccine is, benefits and studies.

Learn how effective the AstraZeneca vaccine is, benefits and studies.

Learn how effective the Moderna vaccine is, benefits and studies.

Is the vaccine permitted in my religious community?

Many religious communities openly support the Covid-19 vaccine, including The Muslim Council of Britain, who confirmed that all approved Covid-19 vaccines are safe to take, with all versions approved by The British Islamic Medical Association.

How does the vaccination process work?

The NHS is offering the Covid-19 vaccine on a priority basis. You'll get a letter, phone call, email or text inviting you for a vaccination appointment when it's your turn to have the vaccine.

When you do, you’ll need to have two doses of the vaccine and go to two appointments. These may be at GP surgery, pharmacy, or special mass vaccination centres. There are also mobile ‘pop-up' vaccination services that are visiting certain communities - some of these do not require an appointment.

Read the experiences of different people who’ve had the Covid-19 vaccination here.

It’s important to remember the following:

  • You don’t need to contact the NHS to ask for the vaccine. You’ll be contacted when it’s your turn.
  • When the NHS does contact you, please attend your booked appointments.
  • It’s so important to continue to follow all the guidance to control the spread of the virus and save lives.

Read more about Covid vaccination appointments

Find out how many people have had the Covid-19 vaccination, and learn more about mass vaccination centres

What to expect at your Covid vaccine appointment

Your vaccine appointment will take place at your GP surgery, local hospital, pharmacy or nearest mass vaccination centre. There are also mobile ‘pop-up- vaccination services that are visiting certain communities. Unless exempt, you will need to wear a face covering to your appointment. 

Here are a few things to expect during your first Covid vaccine appointment:

  • Your appointment could last up to 30-45 minutes (but many are much quicker). If your appointment is at a vaccination centre, you'll be asked for your booking reference number on arrival. If you can, bring along your NHS number with you.

  • Before receiving the Covid vaccine you'll be asked questions about your medical history. It’s important to tell the vaccination staff if you have any serious medical problems, allergies or if you are pregnant.

  • You will then be given an injection of the vaccine into your upper arm, so try and wear something loose, or that can be easily lifted up to allow the vaccinators to get to your arm.

  • After you've had your Covid vaccine, you'll be asked to wait  (up to 15 minutes) as a precaution in the unlikely event that you have a serious reaction.

  • Before you leave your appointment, you'll receive a vaccination leaflet to take home with information about the Covid-19 vaccine you received, and what to expect after your vaccination.

  • You'll also receive a vaccination record card with the date and type of vaccine you received. You will need your vaccination record card for your second appointment.


Volunteers from the Red Cross and other voluntary agencies will be on hand in many of the mass vaccination centres in England and Wales to help guide you through the Covid vaccination process.

Read more about how Red Cross volunteers are helping the NHS to fight the coronavirus pandemic.

What should you do after you get your first Covid-19 vaccine?

After your first vaccine appointment keep your record card safe, and ensure that you bring it to your second appointment. 

All of the vaccines in use in the UK require two doses to provide the best protection. After your first dose, your next appointment should be 8-12 weeks after your first appointment (this may be sooner if you have problems with, or are due to have treatment for your immune system).

If you have not booked your coronavirus vaccine appointment and you have received an invitation, you can book your vaccine appointment on the NHS websiteYou may need your NHS reference number.


If you already have Covid vaccination appointments booked, you can also view, cancel or change your appointment on the NHS website. If you haven’t received an invitation, but think you might be eligible, speak to your GP, or ring 119.

Why do I need to wait 8 weeks between doses? Can I get my second dose of the Covid vaccine sooner?

Although the first people to be vaccinated following the manufacturers guidance received their second doses between 3-4 weeks after their first vaccine, following real world investigation the evidence showed that there was better immune response and protection where longer intervals between doses used.

The current advise from the JCVI is an interval of 8-12 weeks between doses of all available vaccines. The only exception to this would be where the person receiving their vaccination was due to start immunosuppressive treatment (e.g. chemotherapy).

Do I need a vaccine, if I've already had Covid?

If you’ve already had the illness, your body creates antibodies to fight off future infections. However, the jury is still out on exactly how much protection you receive or how long these antibodies last following infection. Vaccination is the best way of protecting yourself and others against the virus in the long term.



How is the British Red Cross involved in vaccinations?

The British Red Cross has been supporting vaccination programmes for generations. Our volunteers and staff are helping at some of the first GP surgeries to roll out the vaccine.

We're also assisting with Covid-19 testing and flu vaccinations around the country. Lots of people turn up alone or feel nervous. We'll be welcoming them, explaining the process, and giving extra support to anyone who needs it in the safest possible way.

Read more in our Stories blog.

We are hugely grateful to everyone playing a role in the incredible task of rolling out the vaccination across the UK. While we must all continue to do our bit in keeping each other safe, there is reason to be optimistic for the future.

Government advice

Find the latest information on Covid travel restrictions, testing and quarantine rules. Learn what you need to travel abroad, and what you need to return to the UK. 

Find the latest information on furlough, return to work, working from home, and information on UK financial support schemes.

Read about the UK government plans for autumn and winter 2021/22.

More government Coronavirus advice.


The information on this page is from the following sources: