25. IDENTIFYING CAUSE OF AEFI CLUSTER Yes Yes Yes Yes Yes Yes No No No No No No Programme error, coincidental or vaccine problem/ “unknown” Manufacturer error, batch problem, or transport/storage error Programme error Coincidental event Vaccine reaction Cluster of AEFIs All cases from only one facility (same lot used at others)? Coincidental event Programme error or vaccine problem All cases got same vaccine or lot? Known vaccine reaction? Similar illness in others who didn’t get vaccine? Similar illness in others who didn’t get vaccine? Rate of reaction within the expected rate?
As an example, the following slides will demonstrate the approach and process to an AEFI investigation.
What is an adverse event following immunization (AEFI)? Although the vaccines in general use in national immunization programmes are extremely safe and effective, adverse events can occur following vaccine administration and no vaccine is perfectly safe. In addition to the vaccines themselves, the process of immunization is a potential source of adverse events. An adverse event following immunization (AEFI) is any adverse event that follows immunization that is believed to be caused by the immunization. Using this terminology allows description and analysis of the event without pre-judging causality. Immunization will naturally be blamed for any event that happens after immunization. Reported adverse events can either be true adverse events, i.e. really a result of the vaccine or immunization process, or coincidental events that are not due to the vaccine or immunization process but are temporally associated with immunization. For the purpose of these guidelines AEFIs are classified into five categories. Immunization can cause adverse events from the inherent properties of the vaccine ( vaccine reaction ), or some error in the immunization process ( programme error ). The event may be unrelated to the immunization, but have a temporal association ( coincidental event ). Anxiety-related reactions can arise from the pain of the injection rather than the vaccine. In some cases the cause of the AEFI remains unknown .
For those who are not aware, the WHO publication, “Surveillance of adverse events following immunization, Field guide for managers of immunization programmes,” (WHO/EPI/TRAM/93.02/REV.1) is an excellent resource book, as a guide for both the development of a national AEFI monitoring and reporting system as well as investigating an AEFI. If copies are required, contact WHO, EPI Programme, either in the respective WHO Regional Offices, or WHO/HQ, Geneva. The four “trigger events” listed above, and some add a fifth one -’Other severe or unusual medical incidents that may be thought to related to immunization,” are important indicators. The basic idea is have these “trigger” events built into a routine reporting system so that they act as triggers to fire a response when something is reported. Most routine EPI do not conduct systematic AEFI investigations on a regular basis unless there is an adverse (real or false) reported.
It is necessary for National Immunization Programmes to define their trigger events, the manner of reporting those events, and the process of responding when a trigger event actually is reported. It is essential to establish clear responsibilities among health workers at the local level, and at higher level, amongst public health experts and NIP programme functionaries. Health workers must be trained and must be given clear guidelines as to what is to be reported normally, what is to be considered abnormal and, in the event of an abnormal event occurring, what actions to take place, who to contact and to whom to pass on the information.
An AEFI investigation follows the same principles of investigation as any disease outbreak investigation. Of course, the actions will differ slightly at different stages.
The slide is self-explanatory
As an example, the following slides will demonstrate the approach and process to an AEFI investigation.
Example of investigation, continued….
Example of investigation continued….
The slide is self explanatory
This slide continues on the example of an AEFI investigation….
Example of AEFI investigation..cotd..
Example, contd… The point to be highlighted here is that investigation without corrective actions is not good enough. Investigation must lead to improvement in the manner in which future activities would be carried out. It is also an opportunity to provide field workers the chance to learn to conduct such investigation and also provide them hands-on training. The second point to be highlighted is that actions must NOT wait till investigation is complete. Patients are priority: treat them and make sure that all available support is given to them. Next is the general public or the parents. Give them enough information, show that you care about this as much as they do and that your interest in the welfare of their children is genuine and professional.
Programme Error and their Consequences
Finally, a surveillance system should be as flexible to make it more appropriate to changing needs. Evaluation of a surveillance system may not be necessary as an annual exercise, but periodically a group of experts must sit together to review the relevance and usefulness of the surveillance system and make changes, where appropriate or necessary.