Global Vaccine Safety

Adverse event following immunization

Aide-Mémoire on causality assessment

aide-memoire cover

Publication details

Number of pages: 4
Publication date: August 2013
Languages: English


Serious illnesses or even deaths may rarely occur after childhood vaccinations. Public health programs are faced with great challenges to establish if the events presenting after the administration of a vaccine are due to other conditions, and hence a coincidental presentation, rather than caused by the administered vaccines.

The Global Advisory Committee for Vaccine Safety (GACVS) commissioned a group of experts to review the previously published WHO Adverse Event Following Immunization (AEFI) causality assessment methodology and aide-mémoire, and to develop a standardized and user friendly tool to assist health care personnel in the processing and interpretation of data on individual events, and to assess the causality after AEFIs. Accordingly a WHO prototype was developed based on definitions and the concepts from the “Definition and Application of Terms for Vaccine Pharmacovigilance - Report of CIOMS/WHO Working Group on Vaccine Pharmacovigilance”. This was reviewed by the GACVS before being approved for field-testing, adoption and distribution.

In July 2013, “Causality assessment of an adverse event following immunization (AEFI), Usermanual for the revised WHO Classification” was published and is currently available online*. This aide-mémoire is a synopsis of the revised methodology that complements the user manual and replaces the previous aide-mémoire. The aide memoire and the worksheet provides the assessor an outline of the new causality assessment process to collect essential information during AEFI investigation and enable the classification of individual AEFI cases in a standardized, consistent and transparent manner.