FAQs about COVID-19 vaccines



This page aims to answer common questions about COVID-19 vaccines. The questions are split into five main sections:

  1. General Questions and Life During the Pandemic
  2. Why Vaccinate and COVID-19 Vaccine Efficacy
  3. COVID-19 Vaccine Safety and Side Effects
  4. COVID-19 Vaccine Ingredients
  5. The Oxford-AstraZeneca Vaccine — ChAdOx1 nCoV-19


1. General Questions and Life During the Pandemic

2. Why Vaccinate and COVID-19 Vaccine Efficacy

3. COVID-19 Vaccine Safety and Side effects

4. COVID-19 Vaccine Ingredients

5. The Oxford-AstraZeneca Vaccine – ChAdOx1 nCoV-19


If you would like to suggest questions to be included on this page, please use our feedback form.

1. General Questions and Life During the Pandemic

How can I get the COVID-19 vaccine?

For information about who is eligible to receive the vaccine in the UK, see COVID-19 vaccines. You will be contacted by the NHS if you are eligible to receive the vaccine. Information about who is eligible to receive the vaccine in the USA is available from the Centers for Disease Control and Prevention.

COVID-19 vaccination strategies for the EU/EEA is available from the European Centre for Disease Control and Prevention.


How will the vaccine ‘feel’ when I receive it?

Each dose of the Pfizer-BioNTech, Moderna and Oxford-AstraZeneca vaccines is given as an injection into the upper arm, similar to other vaccines you receive as an adult. Most people feel a slight sting and a sensation of pressure when the vaccine is being given.  The vaccine won’t feel cold.


Can I take multiple different types of vaccine, as an insurance policy? 

Most of the vaccines developed so far work in similar ways, by making responses against a spike protein. This means vaccinating with different versions is not necessary, however, you may be offered a different vaccine for your booster dose than the one you had for the first two doses. Studies have shown that mixing vaccine schedules is safe and effective against COVID-19.


Can life go back to normal now? 

Vaccines are one tool for combating the virus, but we need multiple vaccines to be successful. These will only be effective if they are used by people around the world, in combination with other public health measures and effective treatments for those who still become ill with COVID-19.


Will I still need to follow social distancing rules and wear a mask after having the vaccine?

A vaccine is one of many tools needed to control the pandemic. We will need to follow public health measures until the rate of virus transmission is much lower. We don’t yet know how well the vaccine prevents transmission of the virus, and this is something researchers are still looking into. Some people in our communities are not able to receive the vaccine yet. It is important that we continue with infection control measures in place to protect everyone in our communities.


How much will the COVID-19 vaccines cost? 

Those who are eligible to receive a COVID-19 vaccine as part of the UK COVID-19 vaccination programme will be entitled to a free vaccine on the NHS. 

As part of an agreement between the University of Oxford and AstraZeneca, the ChAdOx1 nCoV-19 vaccine will be supplied on a not-for-profit basis for the duration of the pandemic and in perpetuity for low- and middle-income countries.


After having the vaccine, will I have a positive result from an antibody test?

The COVID-19 vaccines currently in use target the spike (S) protein of the coronavirus to produce an immune response. Antibody tests used to check for a previous COVID-19 infection have been designed to assess the presence of antibodies against one or other of two different proteins from the coronavirus:

  1. Antibodies against the spike (S) protein which develop after vaccination or COVID-19 infection
  2. Antibodies against the nucleocapsid (N) protein which develop only after COVID-19 infection 

The COVID-19 vaccines currently in use in the UK (Oxford-AstraZeneca, Pfizer-BioNTech and Moderna) only target the spike (S) protein of the coronavirus to produce an immune response. Therefore, after vaccination, presence of antibodies against the S protein is expected, producing a positive result. However, the presence of antibodies against the N protein would not be expected, so for this type of antibody test, a negative result would be seen following vaccination. However, both tests would be expected to show a positive result after a recent COVID-19 infection. Vaccinated individuals who have had an N protein antibody test that is negative do not need additional vaccine doses above those recommended, as the results of this test are not affected by vaccination. 


Can I travel once I've had the vaccine?

Before travelling, you should check the UK FCO travel guidance here which is routinely updated with travel advice related to the COVID-19 pandemic. 

The World Health Organization also has COVID-19 guidance on travel which can be found here. If you have been vaccinated, it is still important to apply caution and practice good social distancing and hygiene. While the approved vaccines are effective at protecting against COVID-19, there are still some areas that need more investigation (e.g. how well the vaccines prevent the spread of disease and the extent to which they offer protection in people who do not show symptoms while infected). 


What precautions should I take between the two vaccine doses?

Data collection is still ongoing on the long-term efficacy of COVID-19 vaccines. However, it is important to continue observing social distancing and following other public health guidelines. It is also important to complete the full vaccination course, including booster doses when you become eligible, to get the maximum protection offered by the vaccines.


Is the vaccine only available as an injection?

Yes, the approved vaccines in the UK are given as injections in the upper arm.



2. Why Vaccinate and COVID-19 Vaccine Efficacy

Should I get the COVID-19 vaccine if I’ve already had COVID-19?

When eligible to receive the COVID-19 vaccine, including booster doses, it is recommended that you take it, even if you have already had COVID-19. There is increasing evidence to show that natural infection with COVID-19 does not lead to long-lasting immunity. COVID-19 vaccination offers the best defence against the virus.


How long will I be protected from the virus with these vaccines? 

At this point we cannot say, but other vaccines using the Oxford ChAdOx1 technology, which is used in the Oxford-AstraZeneca vaccine are proven to provide immune responses that can persist for a year or more. 


What if the coronavirus mutates: will the vaccine still work?

The currently available COVID-19 vaccines protect people from SARS-CoV-2 infection in two ways. The first is by triggering the immune system to produce antibodies against the spike protein which is found on the surface of SARS-CoV-2, and they also stimulate another part of the immune system (T-cells) to help fight infection.  

It is possible that the SARS-CoV-2 virus could mutate its spike protein (the “key” that allows it to get into human cells) in such a way that our antibodies wouldn’t be able to stick to it, and our T-cells wouldn’t be able to “see” it. 

But a change like this could also have a big downside for the virus, because it could make it much more difficult for it to stick to and infect human cells. This might mean that viruses carrying this mutation would naturally die out, as they would be out-competed by viruses with “normal” spike protein.

Data is beginning to come out on whether any of these mutations affect the way that vaccines work, however, more evidence is needed.

In the worst-case scenario where a spike has changed so much that no antibodies or T cells work against it, we would have to produce a new vaccine against the new spike protein. But, scientists are closely monitoring any changes to the virus so that we can predict whether an alternative vaccine might be needed. A benefit of the new types of vaccines (mRNA and adenoviral vectors) is that it is relatively quick and easy to change the genetic code so that it incorporates these mutations, if this was necessary.


Will more booster doses be needed in the future?

At this point we cannot say whether further booster doses may be needed in the future, but this is something that scientists and the government are closely monitoring. Current studies show that booster doses increase immune responses against COVID-19, including new variants, and provide the best defence against the virus. 


Should my child get vaccinated?

Children and young people have a very low risk of becoming seriously ill from COVID-19 disease compared to adults. However, there is evidence of significant transmission of the virus in children and young people, which can lead to children missing school or the virus being passed on to older family members who are more at risk. Currently, all children aged 5-17  in the UK are eligible for two doses of a COVID-19 vaccine. Booster doses are available to all individuals aged 16+. Children aged 12-15 are also eligible for a booster dose if they are clinically at risk or live with an immunosuppressed individual. 


Are the vaccines effective in people over 65 years old?

The overall aim of vaccination programmes, including COVID-19 vaccination, is to protect the most vulnerable populations. The COVID-19 vaccines are found to be effective in preventing severe disease and hospitalisation, including those aged over 65 and those with other medical conditions. In the UK vaccination priority list, the elderly populations are the first groups recommended for vaccination. See the priority list here

An early monitoring report from Public Health England shows that between December 2020 - February 2021 when vaccinations for the elderly age group were initiated, weekly hospitalisations fell by at least 60% in those aged over 65. Similar trends are seen in the weekly rate of deaths for this age group in the same period. See the latest report here.  


3. COVID-19 Vaccine Safety and Side Effects 

Will I get side effects from the vaccine?

The Pfizer-BioNTech, Oxford-AstraZeneca, and Moderna vaccines have a similar safety profile to other vaccines. Side effects that would be expected are mostly “flu-like” symptoms such as a headache, aching, fever, as well as pain and tenderness at the injection site. More information about expected side effects and allergic reactions is available here.


Can you guarantee that no-one will fall seriously ill or even die by taking the COVID-19 vaccines? 

There are risks associated with any medicine, and the COVID-19 vaccine trials have not indicated that these vaccines lead to any unexpected reactions. All of the UK licensed vaccines have similar safety profiles to other vaccines.

In any large trial of a new medicine, incidents are followed up rigorously with an independent group of safety experts. The research teams have collected large safety databases during their trials, and these were submitted to regulators for review. Trial volunteers are still being followed for any longer-term effects. 


Can I get COVID-19 from these vaccines? 

None of the currently approved vaccines are using a live SARS-CoV-2 virus in them; so you cannot get COVID-19 from them. It is common to get symptoms that feel the same as an infection for a few days after you have a vaccine (e.g. feeling “fluey”).  This is a sign that your immune system is responding to the vaccine, not that you have got a real infection. 


These vaccines have been developed so quickly; how do I know that they have been tested properly? 

The COVID-19 pandemic led to an international effort in vaccine development. The urgent need to control the pandemic, and save lives, meant that development processes were significantly accelerated. For example, many of the obstacles which usually slow down vaccine development were removed, with the help of funding, previous scientific advances, collaboration, efficient large-scale manufacturing and thousands of volunteers. This does not mean that steps were skipped, or that safety was compromised. 

More information about the speed of vaccine development is available here: Vaccines 101: How new vaccines are developed


Are the COVID-19 vaccines safe?   

The COVID-19 vaccines currently approved in the UK have been thoroughly reviewed by the Medicines and Healthcare products Regulatory Agency (the MHRA). The regulatory team have completed a full review of the safety information reported from the trials, which includes several months follow-up data from 23,000 people for the Oxford-AstraZeneca vaccine, 44,000 people for the Pfizer-BioNTech vaccine, and 30,000 people for the Moderna vaccine. 


What does safe mean? 

What this means, is that the MHRA has reviewed all the information from the clinical trials of these vaccines. This would include reviewing all the side effects and medical conditions that people in the trials experienced.   

The number of illnesses reported in the vaccinated group is compared with the control group to see whether the vaccine could be associated with an increase in any medical conditions. The rates of illness are also compared with the rate of those illnesses in the general population. For any severe illnesses reported, a specialist doctor involved in treating the person and an independent safety committee consider whether the illness could be associated with the vaccine. 

All the information about adverse events (unexpected illnesses) reported during the trial has been provided to the regulators, and the safety profiles of the Oxford-AstraZeneca, Pfizer BioNTech, and Moderna vaccines are similar to those of other vaccines. 


Can these genetic vaccines alter my DNA?

There has been inaccurate information circulating online about the new technologies used for the Pfizer-BioNTech, Moderna, and Oxford-AstraZeneca vaccines. Whilst these technologies both use genetic codes to produce a harmless version of the spike protein inside the body, this code cannot be incorporated into the body’s DNA. This is because:

  • mRNA vaccines like the Pfizer-BioNTech and Moderna vaccines cannot reach the part of the cell that holds the DNA, called the nucleus.
  • mRNA cannot be translated back into DNA.
  • Both mRNA and adenovirus vaccines do not contain the “specialised tools” needed to “copy” or “edit” DNA.

These vaccines cannot replicate inside the body and only stay in the body for a few days. After helping the cells to produce an immune response against the spike protein, the vaccine is removed by the body.

For more information about the genetic technologies used in the COVID-19 vaccines, please see COVID-19 vaccines.


Can COVID-19 vaccines affect fertility?

There is no evidence that the immune response to coronaviruses has any impact on fertility in animals or humans, and there is no biological mechanism that has been shown to result in an impact on fertility. Regulators have looked at the data carefully from the clinical trials and have not recommended any precautions for individuals planning to become pregnant. 


Is the vaccine safe for Black, Asian, and ethnic minority groups?

There is no scientific evidence to suggest that the COVID-19 vaccines work differently in people of different ethnic groups. All of the approved vaccines to date have intentionally included people from diverse communities in many different countries such as South Africa and Brazil, as part of their clinical trials to investigate both efficacy and safety of the vaccines.


Should I take painkillers before the vaccination?

It is not currently recommended to take painkillers such as ibuprofen, aspirin or paracetamol before your COVID-19 vaccine to prevent side effects. However, if you do experience side effects such as fever, pain, or headaches after receiving the vaccine, you can take medicines containing paracetamol.

For those that take similar medications routinely, you should continue your medications as prescribed.


Is the vaccine safe for individuals with a compromised immune system (including people living with HIV/AIDS, or taking immunosuppressant medicines)?

The currently approved COVID-19 vaccines are not live vaccines and are therefore considered safe in immunocompromised people. The Oxford AstraZeneca vaccine contains a live adenovirus vector, but it has been modified so that it cannot replicate and is also considered safe.

For people that are yet to begin immunosuppression treatments, general best practice is that they should be considered for vaccination at least 2 weeks before starting therapy and when possible, it is preferable to complete the two doses prior to starting immunosuppression.

Studies have shown that some individuals with compromised immune systems have lower or weaker responses to the COVID-19 vaccines. Additional doses may help to raise  immunity provided by vaccines, so those who are immunocompromised are encouraged to take up boosters when eligible. 


Is the vaccine safe for pregnant and breastfeeding individuals?

COVID-19 vaccination is recommended for people who are pregnant, breastfeeding, or trying to become pregnant. COVID-19 disease can cause severe illness in pregnant individuals, especially if they become infected during the third trimester or have underlying health conditions.

There is no evidence that the COVID-19 vaccines cause additional side effects in pregnant people or any harm to the unborn baby. There is no evidence of COVID-19 vaccines affecting fertility.


4. COVID-19 Vaccine Ingredients

Do the COVID-19 vaccines contain human or animal products?

The Pfizer-BioNTech, Moderna, and Oxford-AstraZeneca vaccines do not contain any human or animal derived ingredients.


Do the COVID-19 vaccines contain human foetal cells?

The manufacturing process for the Oxford-AstraZeneca vaccine involves the production of a virus, the adenovirus, which carries the genetic material to the cells inside the body. To produce this virus in the laboratory, a “host” cell line is needed. For some vaccines, chicken cells are used for this process, and for other human cell lines are used to produce the virus. The Oxford-AstraZeneca vaccine uses a cell line called HEK-293 cells. 

HEK-293 is the name given to a specific line of cells used in various scientific applications. The original cells were taken from the kidney of a legally aborted foetus in 1973. HEK-293 cells used nowadays are clones of those original cells, but are not themselves the cells of the aborted foetus.

See also, information about the use of human cell lines in the production of vaccines.


Are the vaccines Halal?

No pork or other animal derived ingredients are contained in the Pfizer-BioNTech, Moderna, or Oxford-AstraZeneca vaccines. The Oxford-AstraZeneca vaccine has ethanol (alcohol) listed as an ingredient, but this is in amounts lower than found in natural foods.

Most scholars have deemed these vaccines permissible. For further information about this, visit the British Islamic Medical Association.


5. The Oxford-AstraZeneca Vaccine — ChAdOx1 nCoV19

How does the Oxford-AstraZeneca vaccine work?  

ChAdOx1 nCoV-19 is made from a virus (ChAdOx1), which is a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees. The adenovirus has been genetically changed so that it is impossible for it to cause infection in humans.   

Genetic material has been added to the ChAdOx1 virus, that is used to make a protein from the COVID-19 coronavirus (SARS-CoV-2) called Spike glycoprotein (S). This protein is found on the surface of SARS-CoV-2 and plays an essential role in how the SARS-CoV-2 virus infects our cells.

Vaccinating with ChAdOx1 nCoV-19 trains the body to recognise and develop an immune response to the spike protein that helps to prevent infection from the SARS-CoV-2 virus if it later enters the body. For more information, see our page on COVID-19 vaccines.


How does the Oxford-AstraZeneca vaccine compare to other vaccines in terms of efficacy?  

Preliminary data indicates that the vaccine is 70.4% effective. 70.4% is highly effective – more effective than the average flu vaccine. We’re going to need a range of vaccines, and in due course we’ll know which vaccines are most effective for different ages, and populations. The most important thing is to get people vaccinated, as this will help to bring the virus under control and prevent people from becoming severely ill.


Does the Oxford-AstraZeneca vaccine stop transmission, or stop you getting ill? 

The trial was designed to show whether the vaccine prevents you from getting ill; we will continue to gather data on asymptomatic infection, and other outcomes.The results of the trial so far (interim results) did show that the vaccine prevented people from getting severe COVID-19.  There were no cases of severe COVID-19 in participants who had the vaccine, and there were two cases in participants who did not have the COVID-19 vaccine, but had the control (placebo) vaccine.


Will the Oxford-AstraZeneca vaccine become like the flu jab, and I'll need it every year? 

At this point we're unable to say, but other vaccines of this type are shown to produce an immune response lasting for a year or more.  



Page last updated: 
Thursday, June 9, 2022