An Adverse Event Following Immunization (AEFI) is any untoward medical occurrence that follows immunization but that does not necessarily have a causal relationship with the administration of the vaccine. Specific criteria must be met to define the events as true adverse events, and there must be no coexisting condition that could explain the reaction that occurs.
Common Reactions to Immunization
Symptoms are categorized as either local, systemic, neurological or other reactions.
Local reactions are related to injection site pain, swelling or redness whereas systemic reactions are usually non-specific and can include tiredness, headache, muscle pain, joint pain, chills or fever.
The severity of a local or systemic reaction can vary. Mild, expected reactions do not require reporting. Unexpected and/or serious reactions must be reported, and an assessment and recommendation by a medical health officer must take place prior to providing further immunizations.
A serious AEFI is one that leads to hospitalization, extends a current hospital stay, causes permanent disability, is life-threatening or results in death.
Serious side effects after receiving vaccines are rare. However, should you develop any serious symptoms or symptoms that could be an allergic reaction, call 911 right away. Symptoms of an allergic reaction include:
- Hives (bumps on the skin that are often very itchy)
- Swelling of the face, tongue or throat
- Difficulty breathing
If you have any concerns about the symptoms you develop after receiving a vaccine, call 811. If you received your vaccine from a pharmacist, please consult them first when possible.
How AEFIs Are Reported and Managed
When an AEFI is reported, Public Health may follow up with you to collect more information and complete an AEFI report form, if appropriate, which will then be sent to the local medical health officer (MHO). The
MHO reviews the report and if there are any recommended follow-ups, you will be contacted with those recommendations.
On both a provincial and national level, these reports are anonymized and then reviewed to identify any unusual concerns. These reports are vital to ensure the safety of all vaccination programs in Canada.