Question Period Note: ADVERSE REACTIONS

Safety is a central consideration for any health product, including vaccines. Canada’s rigorous regulatory system assesses vaccines for safety, efficacy and quality before they are authorized. However, no health product is completely risk-free.
Post-market vaccine surveillance is required to monitor and understand how vaccines behave in the entire population and their real-world impact. Vaccine safety surveillance is critical for rapidly detecting and responding to safety issues, ensuring that the benefits of the vaccine continue to outweigh the risks and supporting vaccine uptake by building public confidence in Canada’s immunization programs.

Key Messages
• The safety and effectiveness of vaccines used in Canada is a top priority for this government.
• Canada’s monitoring systems for adverse events following immunization rapidly detects possible safety issues and investigates them thoroughly.
• Like any medication, vaccines can cause side effects and reactions also known as adverse events. The benefits of vaccines authorized in Canada continue to outweigh their risks.
• As part of the Government’s continued commitment to openness and transparency, Health Canada and the Public Health Agency of Canada provide Canadians with weekly updates on reported adverse events following immunization (AEFI) on Canada.ca.

Adverse events following immunization (AEFI)
An adverse event may occur after a person has been vaccinated. The majority of adverse events are expected mild reactions (e.g., pain, redness, swelling at the injection site, muscle soreness, mild headache), although serious and rare events can occur (e.g., allergic reaction). However, as the World Health Organization states: “The fact that a vaccine was administered within a reasonable time period of the occurrence of an event does not automatically suggest that the vaccine caused or contributed to the event”.

Post-market COVID-19 vaccine safety monitoring
Post-market vaccine surveillance is required to monitor and understand how vaccines behave in the entire population and their real-world impact. Vaccine safety surveillance is critical for rapidly detecting and responding to safety issues, ensuring that the benefits of the vaccine continue to outweigh the risks and supporting vaccine uptake by building public confidence in Canada’s immunization programs.
Canada has a well-established vaccine safety surveillance system that is a collaboration between provinces and territories (P/T), PHAC, Health Canada, and vaccine manufacturers. Manufacturers are required to report serious adverse events to Health Canada as the national regulatory authority, as well as submit regular summaries of global safety information. Health Canada reviews these reports and takes appropriate regulatory actions should new safety issues be identified. In addition, PHAC receives and reviews reports of adverse events following immunization from P/Ts through the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS). This system has been enhanced to support the rollout of COVID-19 vaccines, to expedite the timeliness and sharing of information with partners, and public reporting of adverse events.

To improve vaccine safety surveillance further, the Government of Canada provides funding to: the Immunization Monitoring Program ACTive (IMPACT) network, a paediatric, hospital-based network that reports adverse events to PHAC; and to the Canadian Vaccine Safety (CANVAS) Network, a national web-based platform that collects information about health events occurring after COVID-19 vaccinations, and that provides weekly reports to PHAC and P/T health authorities.

It is notable that, as of the fall 2021, more than 29 million people have received at least one dose of a COVID-19 vaccine in Canada, with side effects reported for 0.029% of all doses administered, of which 0.008% were classified as serious side effects (i.e. requiring hospitalization, life threatening, and/or resulting in persistent or significant disability/incapacity or death).

PHAC and Health Canada continue to closely monitor Canadian and international reports of:
• Thrombosis with thrombocytopenia syndrome following vaccination with the viral vector vaccine AstraZeneca Vaxzevria/COVISHIELD COVID-19 vaccine. Health Canada has updated the product monograph to include information about these very rare events of blood clots associated with low levels of platelets following immunization.
• Guillain-Barré Syndrome (GBS) in Canada following vaccination with the viral vector vaccine AstraZeneca Vaxzevria/COVISHIELD COVID-19 vaccination. Data in Canada indicate a higher number of reports than would normally be expected in the general population. Health Canada has updated the AstraZeneca Vaxzevria/COVISHIELD product monograph to include information on GBS.
• Myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) following vaccination with COVID-19 mRNA vaccines. Data in Canada indicate a higher number of reports in younger people (i.e. less than 40 years of age) than would normally be expected in this age group in the general population. Health Canada updated the product monographs for both Moderna Spikevax and Pfizer-BioTech Comirnaty COVID-19 vaccines to include information around these risks.
• Capillary leak syndrome following vaccination with the AstraZeneca Vaxzevria/COVISHIELD COVID-19 vaccine. Health Canada has updated the product monograph to include information on capillary leak syndrome, including a contraindication for patients who have previously experienced this syndrome.
• Facial paralysis/Bell’s Palsy following COVID-19 vaccination. Health Canada has updated the product monograph for both Pfizer-BioNTech Comirnaty and Moderna Spikevax COVID-19 vaccines to include information on facial paralysis/Bell’s Palsy.

Key Facts
• A robust vaccine safety surveillance system is essential for protecting the health and safety of Canadians, ensuring public confidence in the safety of the COVID-19 vaccines and supporting Canada-wide immunization efforts.
• The Government of Canada continues to work closely with partners to monitor vaccine safety.