Adverse Events Following Immunization (AEFI)
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An AEFI is any event or reaction that occurs after receiving a vaccine. A causal relationship does not need to be proven before reporting. Of particular interest are those of a serious nature, requiring urgent medical attention or are unusual or unexpected events.
Report an AEFI when:
- there is a concern to the patient, caregiver or health professional
- there is an unexpected reaction in terms of type or frequency
- there is a severe reaction requiring hospitalization or urgent medical attention
- it is within 30 days after administering a live vaccine (such as MMR or chickenpox)
- is up to 8 weeks for immune-mediated events
|What to report|
|Patient||unique identifier, date of birth and sex|
|Immunization event(s)||province/territory where given, date, all vaccines given including name, manufacturer, lot number, administration site and route, as well as the number in series of vaccine doses if relevant|
|Adverse event(s)||description, including time of first onset following immunization, duration, health care utilization, treatment and outcome|
|Relevant medical history||underlying disease, known allergies, prior AEFI|
|Associated event(s)||acute illness, current medication, injury, exposure to environmental toxins|
To ensure the safety of vaccines, a surveillance system is set up to monitor adverse events and unusual occurrences. All adverse events investigated by Toronto Public Health are forwarded to the province, then to Public Health Agency of Canada. Adverse events are also compared internationally.