Adverse events following immunization in Canada: Overview

AEFIs are reported health events that occur after vaccination. Many are mild, for example, fever or soreness where the vaccine was given. Some events happen after vaccination by chance and are not caused by the vaccine. AEFI reports should be interpreted as events that happen after vaccination, and not necessarily proven to be caused by a vaccine.

About this dashboard

This dashboard summarizes reports of AEFIs. Reports are submitted to CAEFISS for vaccines administered in Canada between January 1, 2015, and December 31, 2024. This dashboard supports transparency about vaccine safety monitoring in Canada and data exploration.

In addition to AEFI reports submitted to CAEFISS, Health Canada’s Canada Vigilance Program (CVP) collects reports from manufacturers, some health professionals and consumers.

How vaccine safety is monitored

Vaccines are assessed for quality, safety and effectiveness before they are authorized for use in Canada. After authorization, vaccine safety continues to be monitored. Individuals who experience an AEFI are encouraged to report it to a healthcare provider. Public health authorities at the local and provincial or territorial levels collect and review reports of AEFIs that are submitted by healthcare providers and the public. Public health authorities then forward reports to the Public Health Agency of Canada (PHAC) for national aggregation and analysis. PHAC also works with provincial and territorial partners to monitor for unusual or unexpected patterns that may need follow-up and action.

AEFI reports are monitored continuously by the PHAC and Health Canada. Monitoring AEFIs, whether they are proven to be caused by vaccination or not, helps identify unusual patterns. Investigations into vaccine safety can be prompted by:

• new or unusual adverse events
• changes in trends
• severity of specific events

Investigations can include an in-depth medical review and risk assessment. If a safety issue is identified, Health Canada takes appropriate action to protect the health and safety of people in Canada. This could include:

• warning the public of potential side effects
• updating the information in the official product monograph, such as changing the recommended use of the product
• removing the product from the market

Monitoring, investigation and action ensure the continued safety of vaccines over time.

Learn more about how vaccine safety is monitored in Canada.

Learn how to report adverse events.