Global Vaccine Safety

User manual for the revised WHO classification for the causality assessment of an adverse event following immunization (AEFI) – Second edition

WHO

The second edition of the user manual for the revised WHO classification for the causality assessment of an adverse event following immunization (AEFI) was developed by the WHO with support from the Global Advisory Committee for Vaccine Safety (GACVS). This was based on the findings of a scientific study, “Indo- Zimbabwe inter-country study to assess the inter-rater reliability of the WHO AEFI causality assessment methodology and the utility of the new WHO AEFI causality assessment software” that was conducted in April 2017. The study determined that there was realistic agreement between assessors in their findings of assessment and identified areas of the methodology that could be made even more robust by the use of more accurate and clearer language, semantics and graphics. In addition recent surveillance systems and research studies have shed new evidence on areas such as, “substandard and falsified vaccines” and “immunization anxiety” that have been incorporated into this edition.