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#ExploreVaccines: common COVID-19 vaccine questions

We've gathered some of the most common questions that the public have about COVID-19 vaccines. On this page you'll find the answers from our 'Guide to vaccinations for COVID-19' as well as informative infographics to illustrate some answers and engaging videos from our Instagram Q&A sessions

It’s important to understand and address vaccine concerns that are prominent in public discussion and may lead to hesitancy to vaccination. By answering common vaccine questions, the BSI hopes to provide expert information to help everyone make informed decisions about vaccines and their health. We'd like to encourage our members and the research community to share and use these resources to #ExploreVaccines.

There are many ways to play a role in informing the public about COVID-19 vaccination and each person will have their own approach and style. As part of our 'Vaccine engagement starts at home' initiative, we are ramping up our efforts to provide our members and the research community with the necessary support to engage with the public.

How does vaccination work?

Vaccines have been developed to train your immune system and protect against infectious diseases and their serious complications. Once you have been vaccinated, you should have the ability to fight off the infection if you come into contact with it. You will have a level of protection, or immunity against the disease.

Vaccination is the safest way to gain immunity against a disease-causing agent including bacteria or viruses that your body has yet to encounter. Vaccines contain a harmless form of the bacteria or virus that causes the disease you are being immunised against. Your immune system will still recognise the harmless form of the bacteria or virus in the vaccine without making you sick and will produce a specific immune response to fight it off. The immune system then maintains a memory of the bacteria or virus, so if a vaccinated person encounters the bacteria or virus later, their immune system is already prepared to fight it off quickly and prevent an infection from developing.

There are three COVID-19 vaccines currently approved for use in the UK. The Pfizer/BioNTech vaccine and the Moderna vaccine, which are both mRNA vaccines, and the AstraZeneca/Oxford vaccine, which is a viral vector vaccine.

Download these infographics about the types of vaccines for COVID-19 

Is it better to get COVID-19 naturally?

No. The only way to get COVID-19 naturally would be through infection with the SARS-CoV-2 virus that causes the disease. When infected, you become infectious to other people around you and can spread the disease. Infection poses a serious risk to your health, potentially making you very ill and causing long-term health effects. We are still understanding the long-term health consequences of COVID-19 that may be serious for a long time. Vaccination allows you to build up immunity in a safe and controlled way without becoming ill with COVID-19 and passing it to others.

Watch the full Q&A videos 

Has the speed of developing vaccines for COVID-19 compromised safety?

Discover this infographic about how vaccines for COVID-19 have been developed so fast 

No. All the standard safety procedures have been followed during clinical trials on vaccines for COVID-19 and the rigorous regulatory processes have been fully completed as for any other vaccine or medicine.

Vaccines for COVID-19 have been developed at much faster pace due to several reasons. In the emergency state of the COVID-19 pandemic the scientists, doctors, ethics approval boards, manufacturers and regulatory agencies have all come together to work harder and faster.

Scientists have been sharing knowledge openly and promptly during the pandemic and working together across many different countries has allowed greater efficiency.

The greatest barrier to vaccine development is funding. Normally it takes years to raise money to develop a vaccine and at each stage you would have to stop and apply for more funding to carry out the next stage. In the current emergency, many governments and funding bodies have joined forces to remove those financial obstacles. This has allowed large-scale manufacturing of the vaccines to occur in parallel with the clinical trials, which would normally only happen after clinical trials are completed.

The pandemic environment has meant acceleration of clinical trials and faster results because high infection rates are needed to test a vaccine’s effectiveness. Additionally, tens of thousands of keen volunteers have put themselves forward for the clinical trials so recruiting enough volunteers has not been an issue as it may be under normal circumstances.

Finally, scientific advances in vaccine technology have greatly aided the speed of development. Many of the approaches are built on the back of many years of research and could be rapidly deployed once the genetic sequence of SARS-CoV-2 became known.

Watch the full Q&A videos 

How do I know vaccines for COVID-19 are safe?

Before any vaccine can be given to the population it must go through rigorous testing. Like all medicines, vaccines undergo extensive clinical trials, where they are administered and monitored in groups of volunteers. In the UK, the results of the trials are then assessed by the Medicines and Healthcare products Regulatory Agency (MHRA).

No medicine can ever be completely risk free or 100% effective. However, strong licencing processes and safety tests ensure that the health benefits of medicines being given through the NHS greatly outweigh any risks. As vaccines are given to healthy people, these regulatory measures are even stricter, meaning that the level of ‘acceptable risk’ for vaccines is much lower than it would be for other medicines.

Watch the full Q&A videos 

How are long-term side effects known when a vaccine is new?

When any vaccine or medicine is approved, it is continuously and closely monitored for safety and effectiveness by the MHRA. Any suspected side effects are reported by medical providers or patients to the MHRA using the yellow card scheme. Cases of suspected side effects are investigated promptly, while precautionary advice is given and if necessary, guidance is modified. 

Vaccines for COVID-19 have been monitored in large numbers of people for many months in clinical trials and no major safety concerns have arisen. The vaccines for COVID-19 have been monitored for long enough in clinical trials for the MHRA to find the vaccines safe. Long-term side effects appear to be very rare but to be ultra-cautious, the MHRA will continue to monitor for them.


Most side effects of vaccines appear at the time of vaccination or very soon after, within days or weeks, and are minor and temporary. Short-term side effects include soreness and swelling at the site of injection, tiredness or a slight fever, but these are not long-lasting. These side effects are in fact evidence that the immune system is responding to the vaccine as it should be.

Watch the full Q&A videos 

You can find many more infographics, animations, videos, blogs and activities about vaccines and answers to common questions by exploring our public engagement resources.

Explore our COVID-19 public engagement resources

Download our guide to vaccinations for COVID-19