Vaccine Safety

Vaccine safety surveillance is essential to the success of immunization programs.

PHO leads the provincial surveillance of adverse events following immunization (AEFIs). An AEFI is an unwanted or unexpected health effect that happens after someone receives a vaccine, which may or may not be caused by the vaccine.

In Ontario, health professionals are required to report AEFIs to their local public health unit. Public health units investigate AEFIs and provide support to immunizers, individuals, and their families.

If you experience an adverse event after immunization, please contact your health care provider.

For information specific to COVID-19, please visit the COVID-19 Vaccine webpage.

Vaccine Safety Net logo

Public Health Ontario is a member of Vaccine Safety Net – a global network of websites, evaluated by the World Health Organization, that provides reliable information on vaccine safety.

How to Report an AEFI

  1. Complete an AEFI Reporting Form
  2. Send it to your local public health unit

See our AEFI Reporting Fact Sheet for more information.

Having trouble opening PDF forms? Download and save the form directly onto your device.

Vaccine Safety in Ontario

Ongoing surveillance of adverse events following immunization (AEFI) is essential for monitoring vaccine safety and maintaining confidence in immunization programs. Use the following resources to explore and download vaccine safety surveillance data in Ontario from 2012 to 2022.


To obtain or inquire about an immunization record, or for general immunization information, please contact your local public health unit.

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Immunization and Vaccine Preventable Diseases

Updated 1 March 2024