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Covid-19 Primary Care Resources

Adverse effects of Covid vaccines

The most frequently reported adverse effects to the different vaccines and when to report an adverse effect

This information is sourced from the MHRA Guidance on Astrazeneca, Pfizer/BioNTech and Moderna Covid-19 Vaccines and the Specialist Pharmacy Service :

Any vaccine may produce unwanted or unexpected adverse reactions. Currently, the adverse effects from all three approved COVID-19 vaccines are mild, transient and much less serious than developing COVID-19 or the complications associated with COVID-19.

This section looks at the most frequently reported adverse effects to the different vaccines and details how to report an adverse effect.

Reporting of suspected vaccine adverse reaction

Details from NHS Specialist Pharmacy Service can be found here

If you are concerned about an adverse event, it should be reported on a Yellow Card. Reporting form and information can be found at

Alternatively, adverse events of concern can be reported directly to the pharmaceutical company. Please do not report the same adverse effect to both systems as reports between the pharmaceutical company and the MHRA are shared and dual reporting will create duplicates.

  • AstraZeneca: Telephone 0800 0541028
  • Pfizer: Telephone 01304 616161
  • Moderna: Telephone 0800 0857562
  • Janssen: Telephone +44207 6602872

What should I report?

Report any suspected side effects, even minor ones, to any COVID-19 vaccines. When reporting, patients and healthcare professionals are encouraged to provide as much information as possible.

Suspected side effects

When reporting side effects to vaccines the following information should be provided, where available:

  • Information on the person who has experienced the side effect
  • Whether the side effect is related to the first or second dose of the vaccine
  • The date of the vaccination
  • The name and batch number of the vaccine suspected to have caused the side effects
  • A description of the side effects
  • Any other medicines being taken around the same time (including non-prescription and herbal remedies)
  • Any other health condition that the person who experienced the side effect may have

As of 23 June 2021, for the UK:

  • 79,296 Yellow Cards have been reported for the Pfizer/BioNTech vaccine
  • 211,339 have been reported for the Oxford University/AstraZeneca vaccine
  • 6,583 have been reported for the Moderna vaccine
  • 863 have been reported where the brand of the vaccine was not specified

For all vaccines the overall reporting rate is around 3 to 7 Yellow Cards per 1,000 doses administered.

For vaccines, the overwhelming majority of reports relate to injection-site reactions (sore arm for example) and generalised symptoms such as ‘flu-like’ illness, headache, chills, fatigue (tiredness), nausea (feeling sick), fever, dizziness, weakness, aching muscles, and rapid heartbeat. Generally, these happen shortly after the vaccination and are not associated with more serious or lasting illness.

These types of reactions reflect the normal immune response triggered by the body to the vaccines. They are typically seen with most types of vaccine and tend to resolve within a day or two. The nature of reported suspected side effects is broadly similar across age groups, although, as was seen in clinical trials and as is usually seen with other vaccines, they may be reported more frequently in younger adults.

Written by Dr Abdul Zubairu