Halsey NA, Edwards KM, Dekker CL, Klein NP, Baxter R, Larussa P, Marchant C, Slade B, Vellozzi C; the Causality Working Group of the Clinical Immunization Safety Assessment network. Vaccine. 2012 Aug 24;30(39):5791-5798.

Assessing individual reports of adverse events following immunizations (AEFI) can be challenging. The CISA network proposes a systematic approach, with an algorithm intended as a guide, instead of a rigid set of rules for conducting causality assessment. A web-based version of the algorithm is available and it will be updated frequently. Comments and suggestions on the algorithm for improvement are welcome and can be sent to VaccineCausality@gmail.com.

Criteria for determining the diagnosis of the many different AEFI (such as encephalitis or Guillain–Barré syndrome) are beyond the scope of this paper; however, The Brighton Collaboration has developed clinical case definitions for more than 20 AEFI, available here.