Adverse Events Following Immunization (AEFI)

In Ontario, physicians, nurses or pharmacists are required to report all Adverse Events Following Immunizations (AEFIs) to their local public health unit for all vaccines licensed to be administered in Canada (Section 38 of the Health Protection and Promotion Act).

Please do not direct your patient/client to call the Middlesex-London Health Unit to report an AEFI.

What are Adverse Events Following Immunization (AEFI)?

According to the Ministry of Health Infectious Diseases Protocol Appendix B: Provincial Case Definitions for Diseases of Public Health Significance Disease: Adverse Events Following Immunization (AEFIs), an AEFI is any untoward medical occurrence which follows immunization, that CANNOT be clearly attributed to other causes, and does not need a causal relationship with the administration of a vaccine.

Please note:

Reporting of Adverse Events of Special Interest (AESIs) for COVID-19 vaccines enables enhanced monitoring by pre-specifying events which may otherwise not be captured or readily analyzed from a passive surveillance system. Learn more about AEFI and the COVID-19 vaccines.

How to report an Adverse Event Following Immunization (AEFI)?

Public Health Ontario has a published an Adverse Events Follow Immunization Reporting for Health Care Providers in Ontario infographic that provides a summary of the steps for reporting an AEFI and includes a description of the symptoms that qualify for reporting an AEFI.

If your patient/client experiences an AEFI:

(1) Assess if the event is reportable to a public health unit according to Types of Adverse Events Following Immunizations (AEFI) to Report (Middlesex-London Health Unit).

(2) Determine if the event AND the temporal criteria meet the reporting criteria. Resources to help with this include:

• Ministry of Health Infectious Diseases Protocol Appendix B: Provincial Case Definitions for Diseases of Public Health Significance Disease: Adverse Events Following Immunization (AEFIs) (Section 3)
• Find definitions of Adverse Events of Special Interests (AESI)

(3) Complete the Adverse Event Following Immunization Form

It is important to capture the following details:

• For each symptom, include the symptom onset date AND duration in Sections 3 and 4 of the form.
• Describe the patient’s/client’s medical history in Section 4.
• Provide a detailed description of the adverse event in Section 5.
• Describe any health care treatment, the outcome and their dates in Section 7.

(4) Locate the Public Health Unit where your patient/client lives using the Public Health Unit Locator Tool and report the AEFI.

• For patients/clients residing in the Middlesex-London region please fax the completed form to the Middlesex-London Health Unit at 519-663-0416.

If your patient/client experiences an AEFI managed as anaphylaxis:

• Complete the Anaphylaxis AEFI Form
• Locate the Public Health Unit where your patient/client lives using the Public Health Unit Locator Tool and report the AEFI.
• For patients/clients residing in the Middlesex-London region please fax the completed form to the Middlesex-London Health Unit at 519-663-0416.

Background on AEFI

Provincial reporting of AEFIs is an important component of the overall safety assessment of any vaccine. This type of surveillance, commonly called post-marketing or post-licensure surveillance, allows for monitoring of the vaccines throughout implementation in the context of “scaled up” vaccine production and expansion of the population receiving the vaccine.

Individual case reports of AEFIs represent an important source of data as they have the potential to generate signals of adverse events not previously recognized in clinical studies which can be further evaluated.

Important considerations:

• Reporting AEFIs is important for rare adverse events which may not have been evident in clinical trials due to limited sample size.
• In Ontario, passive vaccine safety surveillance relies on reporting of AEFIs by health care providers, vaccine recipients or their caregivers to their local public health unit.
• AEFI reports received by PHUs are investigated, assessed and documented according to provincial surveillance guidelines, as required by the Ontario Public Health Standards (OPHS).

AEFI and the COVID-19 vaccines

Following the authorization of novel Coronavirus Disease 2019 (COVID-19) vaccines in Canada, post-marketing surveillance is being conducted to monitor the safety of these new vaccines throughout the implementation of the immunization program. Provincial reporting of adverse events following immunization (AEFIs) to Canada’s AEFI Surveillance System (CAEFISS) is an important component of post-marketing surveillance in Canada.

Public Health Ontario (PHO) conducts provincial surveillance of AEFIs and provides advice and support for local Public Health Units in the investigation and management of AEFI reports.

All provincially reported AEFIs that meet the confirmed case definition are reported by PHO to the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS) at the Public Health Agency of Canada.

Resources and References:

• Middlesex-London Health Unit: Types of Adverse Events Following Immunizations (AEFI) to Report
• Ministry of Health: Infectious Diseases Protocol Appendix B: Provincial Case Definitions for Diseases of Public Health Significance Disease: Adverse Events Following Immunization (AEFIs)
• Ministry of Health: Public Health Unit Locator Tool
• Public Health Ontario: Vaccine Safety
• Public Health Ontario: Adverse Events Follow Immunization Reporting for Health Care Providers in Ontario
• Public Health Ontario: Adverse Event Following Immunization Form
• Public Health Ontario: Adverse Events of Special Interest (AESIs) for COVID-19 Vaccines Surveillance