Adverse events following immunization (AEFI)

The pandemic influenza A (H1N1) vaccine was an example of where the AEFI classification was used to describe events.

The European Medicines Agency (EMEA) publication "Recommendations for the Pharmacovigilance Plan as part of the Risk Management Plan to be submitted with the Marketing Authorisation Application for a Pandemic Influenza Vaccine" states that there should be "protocols in place [...] to ensure that immunogenicity, effectiveness and safety of the final pandemic vaccine are adequately documented during use in the field (i.e., during the pandemic), since there will be only limited immunogenicity and safety data and no efficacy data at the time of licensing". This publication directed health workers to prioritize reports of the following adverse events:25

  • Fatal or life-threatening adverse reactions,
  • Serious unexpected adverse reactions. This refers to the classification of AEFIs that is discussed in more detail later in this module,
  • AEFI: neuritis, convulsion, anaphylaxis, syncope, encephalitis, thrombocytopenia, vasculitis, Guillain-BarrĂ© syndrome and Bell's palsy.
The Brighton Collaboration website

For each of the above AEFI, standard case definitions from the Brighton Collaboration were used if available. This helped compare data from different countries.

Click on the link to learn more about the Brighton Collaboration, and how they helpt to improve the standardization in the reporting of data.