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Questions on vaccine safety and effectiveness


How can I be sure that the vaccine is safe & effective?

The NHS will not offer any vaccinations to the public until independent experts have signed off that it is safe, and beneficial to do so.

There are three different Covid-19 vaccines currently available in the UK under the NHS - the Pfizer/BioNTech, the Moderna, and Oxford/AstraZeneca COVID-19 vaccines.

The MHRA, the official UK regulator, has approved these as safe and offering a high level of protection, and we have full confidence in their expert judgement and processes. 

As with any medicine, vaccines are highly regulated products. There are checks at every stage in the development and manufacturing process, and continued monitoring once they are authorised and being used in the wider population too.


The vaccine was developed very quickly – how was this possible without cutting corners?

The global nature of the pandemic has meant that the development of vaccines has been the focus of huge amounts of funding, knowledge and resource from countries all around the world. It has also been possible to recruit patients to be involved in testing the vaccine much more quickly.

It’s also important to understand that these vaccines haven’t been developed from nowhere. Scientists had already been working on vaccines against the SARS group of viruses, of which Covid-19 is just one, many years previously.

All of the vaccine that have been approved for use in the UK have met very strict standards of safety, quality and effectiveness set out by the Medicines and Healthcare products Regulatory Agency (MHRA).

None of the other vaccines under development will be available until they have passed those same strict standards either, which apply to every vaccine the NHS uses.


Should I be worried about reports of blood clots linked to the Oxford AstraZeneca vaccine?

Blood clotting is a condition that can and does happen in the general population at any time, including those who have not been vaccinated too.

It's also important to consider that blood clots are a common side-effect of getting coronavirus - and the statistical odds of getting one after catching the virus are far higher than from the vaccine. 

However, the MHRA is carrying out detailed reviews of reports of an extremely rare blood clotting problem affecting a small number of people who have had the Oxford/AstraZeneca vaccine.

For the vast majority of people, the benefits of being vaccinated far outweigh any rare risk of clotting problems. The COVID-19 vaccine can help stop you and those you love from getting seriously ill or dying from coronavirus. 

However, to be extra cautious, the government has advised that people under 30 without other health conditions should have another COVID-19 vaccine instead of the Oxford/AstraZeneca vaccine. Currently both Pfizer or Moderna are being offered locally for all under 30s. This means that everyone can still get a vaccine with peace of mind.

Find out more about COVID-19 vaccination and blood clotting on GOV.UK


I want to check the vaccine is safe for me because of a condition, allergy, or medication that I am on. Who can I speak to for advice?

The vaccines are safe and effective for the vast majority of people. However, you should not have the COVID-19 vaccine if you have ever had a serious allergic reaction (called 'anaphylaxis') to a previous dose of the same vaccine or any of the ingredients in the vaccine. Please speak to you own GP if you need further advice on your suitability.


I’m not convinced that the vaccine works very well - is it really worth getting?

The Medicines and Healthcare Products Regulatory Agency (MHRA), the UK's regulator, has approved both vaccines available in the UK as highly effective in protecting individuals against COVID-19.

All of the latest studies/data shows that the UK’s approved vaccines can provide anywhere between 70% to over 100% protection in individuals, and is therefore well worth getting.


Can’t I just wait to catch Covid-19, and become naturally immune?

The vaccine is extremely effective at training the body’s immune system to fight off the COVID-19 virus, and having the vaccine is a much safer way to gain immunity that waiting to catch the virus with its many known health risks, and hoping that you don’t become seriously ill, or develop long covid later.


Should I be worried about the side-effects of getting the vaccine?

We want to reassure everyone that the vast majority of people experience either no side effects, or very mild ones after having a covid-19 vaccination.

The most commonly reported side-effects are:

  • having a slightly heavy arm
  • experiencing mild flu-like symptoms for a day or so after the vaccine – such as temporary headache or chills

Please also be reassured that checking for any history of allergies, as well as being able to deal with any allergic reactions in the very rare instances that they do happen, is a central part of training for all vaccinators.