Causality assessment of an adverse event following immunization (AEFI), 2nd edition

The second edition of the manual was developed by the WHO with support from the Global Advisory Committee for Vaccine Safety (GACVS) based on the findings of a scientific study conducted in April 2017, “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”. The quantitative aspect of the study determined that there was realistic agreement between assessors in their findings. The qualitative aspect of the study 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 feedback from surveillance systems and research studies have shed new evidence on areas such as, “substandard and falsified vaccines” and “immunization anxiety” that have been incorporated.