An AEFI is an untoward medical event which follows immunisation and does not necessarily have a causal relationship with the administration of the vaccine. The adverse event may be an unfavourable or unintended sign, abnormal laboratory finding, symptom or disease. AEFIs are grouped into five categories, which are:

  • • Vaccine product-related reaction – An AEFI that is caused or precipitated by a vaccine due to one or more of the inherent properties of the vaccine product e.g. Extensive limb swelling following a vaccination.
  • • Vaccine quality defect-related reaction – An AEFI that is caused or precipitated by a vaccine that is due to one or more quality defects of the vaccine product including its administration.
  • • Immunisation error-related reaction – An AEFI that is caused by inappropriate vaccine handling, prescribing or administration and thus by its nature is preventable.
  • • Immunisation anxiety-related reaction – An AEFI arising from anxiety about the immunisation e.g. hyperventilation.
  • • Coincidental event – An AEFI that is caused by something other than the vaccine product, immunisation error or immunisation anxiety. e.g. a fever occurs at the time of the vaccination (temporal association) but is in fact caused by something else. Coincidental events reflect the natural occurrence of health problems in the community with common problems being frequently reported.

An AESI is a pre-specified medically significant event that has the potential to be causally associated with the vaccine product based on past experience, the technology used to make the vaccine or the infection the vaccine is used to protect against. AESIs need to be carefully monitored and any potential association to vaccination confirmed by further investigation.

Causality assessment is a procedure used to determine the relationship between a medicine/vaccine and the occurrence of an adverse event.

Two or more cases of the same event or similar events related in time, geography, and/or the vaccine administered.

An event that is not “serious” and that has no potential risk to the health of the recipient of the vaccine.

A set of activities relating to detection, assessment, understanding, and prevention of adverse.

Information on a new or known adverse event that may be caused by the vaccine and requires further investigation. Safety signals can be detected from a wide range of sources such as individual case safety reports, clinical studies and scientific literature.

An AEFI is considered serious if it:

  • • is a medically important event
  • • requires hospitalisation or prolongs an existing hospitalisation
  • • causes persistent or significant disability or incapacity
  • • is life threatening
  • • causes a congenital anomaly/birth defect
  • • results in death.

It is possible for different people to have experienced the same event but for the report to be serious for one person and non-serious for another person.

Severe is used to describe the intensity of a specific event (as in mild, moderate or severe); the event itself, however, may be of relatively minor medical significance (e.g. Fever is a common relatively minor medical event, but according to its severity it can be graded as mild fever or moderate fever).

A biological substance that is administered to individuals to elicit immunity (protection) against a specific disease.

There are only four requirements for a valid AEFI report:

  1. 1. one patient identifier (e.g. name, initials, gender, date of birth, age)
  2. 2. other medicine(s) taken
  3. 3. suspected reaction(s)
  4. 4. reporter details.

These four requirements are the minimum requirements. However, including more information in the report helps to investigate the reaction more quickly.