COVID-19 Vaccines: Frequently Asked Questions

The information below provides responses to frequently asked questions on COVID-19 vaccines. Please click on an item below to view more information.

How are COVID-19 vaccines being developed and approved for use?

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

The vaccines are first tested in the laboratory before being tested in human volunteers in studies called clinical trials. These tests help confirm how the vaccines work and, importantly, also evaluate their safety and efficacy – or effectiveness.

To gain approval (authorisation) for a vaccine, the vaccine developer must submit the results of all testing and trials to the regulator. The regulator carries out a scientific evaluation of the vaccine’s safety, effectiveness and quality, before concluding whether there is sufficient scientific evidence supporting approval.

Detailed information about how a vaccine is developed, evaluated, approved and monitored is available on the website of the European Medicines Agency (EMA).

For COVID-19 vaccines, development and approval is progressing more rapidly than usual due to the public health emergency caused by the virus. Regulatory agencies are diverting resources to speed up processes and reduce timelines for the evaluation and approval of COVID-19 vaccines. Please see the EMA website for further detail on additional supports for developing and approving COVID-19 vaccines.

What evidence of safety and effectiveness is required before a vaccine is approved for use?

COVID-19 vaccines will be evaluated against the same high standards as any other medicine. Vaccines are only approved by regulators after scientific evaluation has demonstrated that their overall benefits outweigh their risks. A vaccine's benefits in protecting people against COVID-19 must be far greater than any side effects or potential risks.

Vaccine developers must submit specific data about their product. The regulator then carries out a thorough assessment of the data to reach a scientific opinion on whether the vaccine is safe, effective and of good quality, and is therefore suitable to vaccinate people.

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

The data submitted by a vaccine developer must include information on the following:

  • 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;
  • 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 vaccines, 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;
  • the way risks will be managed and monitored once the vaccine is authorised; the risk management plan, 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.

Who approves the vaccine for use in Ireland?

The HPRA is the national regulator for medicines in Ireland and we work closely with the European Medicines Agency (EMA). For COVID-19, it is expected the applications for vaccines will be made to the EMA and if approved, they can be used in all EU Member States. Ireland, through the HPRA, is an active participant in all European reviews. The HPRA contributes directly to the assessment of all new medicines and the monitoring of their safety once in use. This will also be the case for COVID-19 vaccines and treatments.

Since the beginning of the pandemic, regulators across the world, including the HPRA, have collaborated in an unprecedented manner to offer rapid expert advice and guidance on the best methods and design of clinical trials. This global co-operation is fully focussed on safely accelerating access to new vaccines once they are shown to be safe and effective.

The HPRA is also an expert member of NPHET, advising on the regulatory aspects of medicines, including vaccines, and medical devices.

Which COVID-19 vaccines have been approved?

On 21 December 2020, the European Commission confirmed it had granted a conditional marketing authorisation for Comirnaty, developed by BioNTech and Pfizer, making it the first COVID-19 vaccine authorised in the EU.

On 6 January 2021, the European Commission confirmed it had granted a conditional marketing authorisation for COVID-19 Vaccine Moderna.

On 29 January 2021, the European Commission confirmed it had granted a conditional marketing authorisation for COVID-19 Vaccine AstraZeneca.

On 11 March 2021, the European Commission confirmed it had granted a conditional marketing authorisation for COVID-19 Vaccine Janssen.

Please visit Approval of COVID-19 Vaccines for information on the approval process and the current status of other vaccines under evaluation by the EMA.

How long will immunity from a vaccine last? Will vaccines protect vaccinated people if the virus mutates?

Currently, because the virus is so novel, there is not enough knowledge on how long the immunity conferred by the vaccines will last after vaccination, or whether there will be a need for periodic booster doses.

Typically, viruses mutate (the genetic material in the virus changes). This happens at different rates for different viruses and mutations do not necessarily affect how well the vaccine works against the virus.

Some vaccines against viral diseases remain effective many years after their development and provide long-lasting protection, such as vaccines for measles or rubella.

On the other hand, for diseases such as flu, virus strains change so often and to such an extent that the vaccine composition must be updated on a yearly basis for it to be effective.

The scientific community and regulators will monitor whether the virus changes over time and, if so, whether vaccines can protect people from infection with new variants.

How will the safety of COVID-19 vaccines be monitored after approval?

The HPRA, together with the EMA and other EU medicines agencies, will continuously assess safety data emerging in relation to COVID-19 vaccine use, through well established safety monitoring systems. Any potential safety concerns identified will be addressed by taking appropriate regulatory action to safeguard individual and public health and communicating with the public in a transparent and timely manner. More information is available in the EU safety monitoring plan.

The HPRA strongly encourages healthcare professionals and members of the public, to report suspected adverse reactions (side effects) to COVID-19 vaccines to the HPRA.

Safety updates providing an overview of the national reporting experience for COVID-19 vaccines are available on our Safety Notices page.

For more information on safety monitoring, please visit our COVID-19 vaccines: Reporting a side effect page.

How can I report side effects of COVID-19 vaccines?

To report a suspected adverse reaction (side effect) to a COVID-19 vaccine, please use the COVID-19 Vaccine Adverse Reaction Reporting Form.

Adverse reactions (side effects) can be reported to the HPRA by members of the public, carers or healthcare professionals.

Reporting adverse reactions (side effects) to the HPRA supports continuous monitoring of the safe and effective use of COVID-19 vaccines.

When reporting, as much information as is known should be provided, and where possible, the vaccine batch number should be included.

The HPRA cannot provide clinical advice on individual cases. Members of the public should contact their health care professional (their doctor or pharmacist) with any medical concerns they may have.

Resources for more information

Organisations providing information on COVID-19 vaccines 

Evaluating and approving vaccines 

Monitoring the safety of vaccines 

  • The EU plan for monitoring the safety of COVID-19 vaccinations after approval: EMA: Safety Monitoring Plan

  • How regulators monitor the safety of vaccines in Europe: 

    • European Centre for Disease Prevention and Control video
    • European Commission video
    • European Commission factsheet