Special considerations for AEFI surveillance

Three major factors need to be given special consideration because they could affect the type of AEFI surveillance and its outcomes.

Training for health workers

Health workers administering vaccinations are on the frontlines and are usually the first responders to an AEFI. They need to be trained how to detect, report, and respond to adverse events, including stabilizing the patient (for example, in a case of anaphylaxis) and communicating with parents, the community and the media. 

Determining causality

Difficulties in determining causation between events that are linked in time are common to all drug and vaccine safety monitoring systems. This is particularly challenging in the case of vaccines, because:

• Information on "dechallenge and rechallengeChallenge, dechallenge and rechallengeA testing protocol in which a medicine or drug is administered, withdrawn, then re-administered, while being monitored for adverse effects at each stage. It is one of the standard means of assessing adverse drug reactions but is usually not possible in vaccine trials or AEFI investigations." is usually missing,
• Vaccines are given to most of the country's birth cohort at an age when coincidental disease are likely,
• Several vaccines are likely to be administered at the same immunization visit,
• Vaccine storage, handling, transport and administration must adhere to specific conditions. Any of these, if not done correctly, can result in an adverse event. The possibility of immunization errors therefore must be investigated.

Independent review is needed

There is a need for independent review of adverse events, separate from the immunization programme. Causality assessmentCausality assessment (or causality association)The systematic review of data about an AEFI case to determine the likelihood of a causal association between the event and the vaccine(s) received. requires a team of investigators, including an immunologist or other experts, depending on the nature of the adverse event. The team usually does not directly include officials from the NIP. They may be perceived to have a conflict of interest as they are responsible for investigating adverse events related to administration of a vaccine.