COVID-19 vaccines: key facts

The European Commission has authorised the first vaccines to prevent COVID-19 in the European Union (EU), following evaluation by the European Medicines Agency (EMA). EMA is liaising closely with developers of other potential COVID-19 vaccines, mobilising its own resources and cooperating with regulatory partners, to ensure safe and effective vaccines reach patients as soon as possible.

Why are vaccines to prevent COVID-19 needed?

COVID-19 vaccines are medicines that prevent disease caused by the novel coronavirus SARS-CoV-2 by triggering an immune response.

Safe and effective vaccines for COVID-19 are needed because they protect individuals from becoming ill. This is particularly important for healthcare professionals and vulnerable populations such as older people and people with long-term diseases.

The COVID-19 pandemic is a global crisis, with devastating health, social and economic impacts. COVID-19 can cause severe disease and death. It has unknown long-term consequences in people of all ages, including in otherwise healthy people. 

Is there a vaccine to protect against COVID-19?

The European Commission has authorised the first vaccines to prevent COVID-19 in the EU, following evaluation by EMA. For more information, see Treatments and vaccines for COVID-19: authorised medicines.

Due to the urgency posed by the pandemic, efforts are ongoing to develop and study other COVID-19 vaccines in order to approve and make them available as soon as possible. 

For the latest information, see Treatments and vaccines for COVID-19

Effective vaccines, together with other public health measures and therapeutic treatments, are a key component in overcoming COVID-19.

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Vaccines work by preparing a person's immune system (the body’s natural defences) to recognise and defend itself against a specific disease.

Most research on COVID-19 vaccines involves generating responses to all or part of a protein (spike protein, or protein S) that is unique to the virus that causes COVID-19. When a person receives the vaccine, it will trigger an immune response.

If the person is infected by the virus later on, the immune system recognises the virus and, because it is already prepared to attack the virus, protects the person from COVID-19.

You can find more information on the European Vaccination Information Portal

What process and methods are used to develop and approve COVID-19 vaccines?

COVID-19 vaccines are developed following the same legal requirements for pharmaceutical quality, safety and efficacy as other medicines. 

Like all medicines, COVID-19 vaccines’ effects are first tested in laboratory, including in animals, then vaccines are tested in human volunteers. 

For more information, see  COVID-19 vaccines: development, evaluation, approval and monitoring

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Before approval, all vaccines in the EU are evaluated against the same high standards as any other medicine.

What is different for COVID-19 vaccines is that speed of development and potential approval is much faster due to the public health emergency

EMA has put in place a dedicated expert task force and rapid review procedures to evaluate high-quality applications from companies in the shortest possible timeframes, while ensuring robust scientific opinions. 

The European Commission makes use of all existing flexibilities to accelerate the approval of any potential vaccines for use across the EU, but this is only possible if EMA receives sound scientific evidence establishing that a vaccine's benefits are greater than any risks.

You can find more information on how vaccines and other medicines are evaluated and authorised in the EU on:

Why did development only start after the pandemic was declared?

Vaccines can only be developed when the infectious agent is known.

Since SARS-CoV-2 is a new virus that had not been seen before, development of a vaccine to protect against COVID-19 could only be started once the virus emerged and its genetic make-up had been analysed.

However, vaccine development builds on experience and technologies used for other vaccines.

When will the vaccines be approved?

The European Commission has authorised the first vaccines to prevent COVID-19 in the EU, following evaluation by the EMA. For more information, see Treatments and vaccines for COVID-19: authorised medicines.

EMA's CHMP assesses marketing authorisation applications for COVID-19 vaccines in an expedited manner.

It can conclude its assessment once the data on the quality, safety and efficacy of the vaccine are robust and complete enough to determine whether the vaccine’s benefits outweigh its risks. For more information, see Treatments and vaccines for COVID-19: authorised medicines.

Information on the COVID-19 vaccines EMA is currently evaluating is available under Treatments and vaccines for COVID-19: medicines under evaluation.

For vaccines currently at earlier stages of development, EMA expects to receive enough data to start a scientific review in 2021.

For more information on EMA’s expedited evaluation procedure for COVID-19 vaccines, see COVID-19 vaccines: Scientific evaluation and approval: Accelerated evaluation. To read more about what EMA requires for approval, see COVID-19 vaccines: studies for approval.

What type and amount of data is needed for approving a safe and effective vaccine?

COVID-19 vaccine developers need to submit specific data on their vaccine. EMA then carries out a thorough assessment of these data to reach a scientific opinion on whether the vaccine is safe, efficacious and of good quality and is therefore suitable to vaccinate people.

The data should show the vaccine’s efficacy in protecting against COVID-19 (how well the vaccine works in clinical settings) and its safety.

Efficacy is measured by looking at how well the vaccine works in the study, for example how well the vaccine prevents symptomatic disease. These efficacy measures are called ‘endpoints’. Efficacy endpoints are required because COVID-19 is a new disease and because there are no known indicators (such as the levels of antibodies in the blood) that can predict protection.

For more information on the studies required for approval, see  COVID-19 vaccines: studies for approval.

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The safety requirements for COVID-19 vaccines are the same as for any other vaccine in the EU and are not lowered in the context of the pandemic. 

The data submitted in a marketing authorisation application for a COVID-19 vaccine must include information on:

  • the group of people to be given the vaccine;
  • its pharmaceutical quality, including information on the identity and purity of the vaccine components and its content and biological activity (potency);
  • data on each step of manufacturing and on the controls used to ensure that each batch of vaccine is consistently of good quality;
  • compliance with international requirements for laboratory testing, vaccine manufacture and conduct of clinical trials (‘good laboratory practice’, ‘good clinical practice’ and ‘good manufacturing practice’);
  • types of immune responses induced by the vaccine;
  • the effects observed in the groups of people to be given the vaccine;
  • the vaccine’s side effects observed in vaccinees, including if there are any data in special populations such as older people or pregnant women;
  • information intended to be gathered from follow-up studies after authorisation (e.g. long-term safety data or long-term immunity);
  • prescribing information to be provided to patients and healthcare professionals (i.e. the summary or product characteristics or SmPC, labelling and package leaflet), which is drafted by the developer and reviewed and agreed by EMA’s scientific committees;
  • the way risks will be managed and monitored once the vaccine is authorised; the risk management plan (RMP), a document with information about any possible (known or potential) safety concerns with the vaccine, the way risks will be managed and monitored once the vaccine is authorised and what information is intended to be gathered from follow-up studies. The RMP is evaluated by EMA’s safety committee, PRAC.

How long will immunity from a vaccine last?

It is not known how long the immunity conferred by a COVID-19 vaccine will last when the vaccine is first authorised.

This is because more data is needed from ongoing and additional studies in the long term to understand how long protection lasts after vaccination. 

For example, the company that markets Comirnaty, the first authorised COVID-19 vaccine in the EU, will continue to follow up the people vaccinated in its main clinical trial for 2 years. This will allow the company to gather information on the duration of protection generated by the vaccine.

EU authorities will also be coordinating independent studies on the use of COVID-19 vaccines in real life, to gather more information on their long-term safety and benefit in the general population.

The results of these long-term studies will inform future vaccination strategies.

Vaccination policies are not decided by EMA but by public health agencies in EU member states. More information is available on the European Vaccination Information Portal

Can vaccines protect people against the virus when it has mutated?

Viruses typically mutate. A mutation is when the genetic material in the virus changes.

Mutations happen at different rates in different viruses. They do not necessarily affect how well a vaccine works against a virus.

The scientific community and regulators are closely monitoring how SARS-CoV-2 (the virus that causes COVID-19) changes over time, and how well COVID-19 vaccines can protect people against COVID-19 caused by any new variants of the virus that appear.

Vaccines against some viral diseases remain effective for many years after their development and provide long-lasting protection. These include vaccines against measles and rubella (German measles).

Vaccines against other viral diseases like influenza (flu), on the other hand, need updating every year to remain effective. This is because the flu virus mutates often and to a large extent, with new variants appearing with each flu season.


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