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Vaccine Safety

In Ontario, health professionals are required to report adverse events following immunization (AEFIs) to local public health units. The public health units investigate adverse events and provide support to immunizers, individuals, and their families. Public Health Ontario analyzes AEFIs that are reported in Ontario to monitor the safety of administered vaccines and contribute to national and international vaccine safety surveillance systems.

​What is an AEFI?

An adverse event following immunization is an unwanted or unexpected health effect that happens after someone receives a vaccine, which may or may not be caused by the vaccine. If you have an AEFI, you should contact your health care providers. AEFIs need to be reported to the local public health unit.

How do I report an AEFI in Ontario?

To report adverse events to your local public health unit, use Public Health Ontario’s Adverse Event Following Immunization (AEFI) Reporting Form.

Contact us


For health care provider AEFI inquiries, including questions about the form or determining if an AEFI should be reported, please contact your local public health unit.



2013 report


The Annual Report on Vaccine Safety in Ontario, 2013, is a comprehensive annual provincial assessment of vaccine safety, including a summary of adverse events following immunization (AEFI) reported in Ontario following vaccines administered in 2013.


Previous report and resources




Immunizer overview


The Immunizer Overview is a tool for health professionals to communicate with patients about vaccine safety. It includes a brief summary of the Annual Report on Vaccine Safety in Ontario, 2013, and information about Ontario's vaccine safety surveillance system.


Additional resources

for immunization providers
for public health units
Snapshots Query Lab Tools

Reporting f​orms
Ontario AEFI reporting form

AEFI reporting in Ontario: An overview for immunizers

These forms are best viewed in Internet Explorer. To view these forms in Google Chrome or Apple Safari, please follow the instructions below:

Right click and download the form and then open the saved file with the Adobe Reader installed on your computer. 

Surveillance forms
Anaphylaxis reporting form

Intussusception investigation form

Guidance documents

 iPHIS User Guide for Adverse Events Following Immunization (AEFI)


Training resources

iPHIS training webinar
April 23 and 24, 2014
To access a recording of this training session, please contact

Vaccine Safety Surveillance Workshop
January 21, 2013

Vaccine Safety in 2013: it’s everyone’s business!
PHO Grand Rounds
November 25, 2014

Vaccine Safety: it’s everyone’s business!
PHO Grand Rounds
November 19, 2013

Not a shot in the dark: Restoring confidence in vaccine safety
PHO Grand Rounds
October 9, 2012

Adverse event reporting for new vaccines
The Ontario Public Health Convention
April 4, 2012 






Simulation Study of the Effect of Influenza and Influenza Vaccination on Risk of Acquiring Guillain-Barré Syndrome. Emerging Infect Dis. 2015 Feb;21(2). Epub ahead of print.

Vaccine safety implications of Ontario, Canada’s switch from DTaP–IPV to Tdap–IPV for the pre-school booster. Vaccine. 2014 Nov 12;32(48).

Did narcolepsy occur following administration of AS03-adjuvanted A(H1N1) pandemic vaccine in Ontario, Canada? A review of post-marketing safety surveillance data. Euro Surveill. 2014 Sep 11;19(36)

Adverse events following immunization in Ontario's female school-based HPV program. Vaccine. 2014 Feb 19;32(9):1061-6

The risk of Guillain-Barré Syndrome following seasonal influenza vaccination and influenza healthcare encounters, a self-controlled study. Kwong JC, Vasa PP, Campitelli MA, Hawken S, Wilson K, Rosella LC, Stukel TA, Crowcroft NS, McGeer AJ, Zinman L, Deeks SL. Lancet  Infect Dis. 2013 Sep;13(9).

Adverse Events following 12 and 18 Month Vaccinations: a Population-Based, Self-Controlled Case Series Analysis. Wilson K, Hawken S, Kwong JC, Deeks S, Crowcroft NS, Van Walraven C, Potter BK, Chakraborty P, Keelan J, Pluscauskas M, Manuel D. PLoS One. 2011;6(12).

Estimating background rates of Guillain-Barré Syndrome in Ontario in order to respond to safety concerns during pandemic H1N1/09 immunization campaign. BMC Public Health. 2011; 11: 329.

Related Links


Vaccine Fact Sheets
Ministry of Health and Long-Term Care (MOHLTC)

Canadian Immunization Guide. Part 2: Vaccine Safety
Public Health Agency of Canada (PHAC)

Practice Point: Canada's Vaccine Safety Program
Canadian Paediatric Society (CPS)

Canadian Adverse Events Following Immunization Surveillance System (CAEFISS) 
Public Health Agency of Canada

Product monographs for vaccines authorized for use in Canada
Health Canada

Adverse Effects of Vaccines: Evidence and Causality
Institute of Medicine (IOM)

Course on Vaccine Safety Basics
World Health Organization (WHO)




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