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Vaccine resources for health and social care professionals - Vaccine safety

Contraindications and special considerations

Adverse events following immunisation

There is no such thing as a “perfect” vaccine, which gives 100% protection to everyone who receives it, or one that is entirely safe for everyone in the population to receive.  Effective vaccines (i.e. vaccines inducing protective immunity) may produce some undesirable side effects, but most are mild and generally resolve quickly. Many events thought to be related to vaccination are actually not due to the vaccine itself. It is usually not possible to predict which individuals might have a reaction to a vaccine.  Following guidance on contraindications will ensure the risk of serious adverse effects is minimised.

Reporting vaccine safety issues

The Yellow Card Scheme is vital in helping the Medicines and Healthcare products Regulatory Agency (MHRA) monitor the safety of vaccines in the UK. All serious suspected adverse drug reactions (ADRs) for established medicines and vaccines should be reported, even if the effect is well recognised. Causality does not have to be proved to report a suspected ADR, only a suspicion is needed.

For urgent issues related to a suspected defect in a vaccine, you should report to the MHRA Defective Medicines Reporting Centre on the UK government website.

Suspected side effects of vaccines and medicines can be reported through the Yellow Card scheme at the MHRA website.

The public and healthcare professionals can find further information on the work of the MHRA agency, safety warnings, and how to report any problems at the UK government website.

The World Health Organisation (WHO) keeps a register of reliable validated websites which can be recommended to parents and professionals.

Vaccine alerts

The latest MHRA safety warnings, alerts and recalls can be found at the UK government website. 

Black triangle scheme

New vaccines that are under additional monitoring have an inverted black triangle symbol (▼) displayed in their package leaflet and summary of product characteristic, together with a short sentence explaining what the triangle means – it does not mean the vaccine is unsafe. All suspected ADRs for these vaccines should be reported. Information on the Black Triangle Scheme can be found on the UK government website.

Surveillance and monitoring for vaccine safety

Surveillance and monitoring for vaccine safety on the green book, chapter 9.

Vaccination surveillance information can be found at:

Vaccine damage payment scheme

Vaccine Damage Payment Scheme on the green book, chapter 10.

The Vaccine Damage Payment Scheme provides a single, tax-free payment to people (or their families) who have suffered severe mental and/or physical disablement as a result of immunisation against certain diseases.

Page last reviewed: 16th June 2025