This is a summary, written by members of the CITF Secretariat, of:

Bettinger JA, Sadarangani M, De Serres G, Valiquette L, Vanderkooi OG, Kellner JD, Muller MP, Top KA, Isenor JE, McGeer A, Marty K. The Canadian National Vaccine Safety Network: surveillance of adverse events following immunisation among individuals immunised with the COVID-19 vaccine, a cohort study in Canada. BMJ Open. 2022 Jan 1;12(1):e051254. doi: 10.1136/bmjopen-2021-051254

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

CANVAS-COVID tracks the safety of COVID-19 vaccines through electronic surveys sent to people who have been vaccinated. Over 1.3 million individuals have contributed data so far. The study team, led by Dr. Julie Bettinger from the BC Children’s Hospital Research Institute, has published their detailed protocol in BMJ Open outlining the study design and its objectives.

The Canadian Vaccine Safety (CANVAS) Network normally monitors the safety of seasonal influenza vaccines, but has since pivoted to monitor COVID-19 vaccine safety though CANVAS-COVID.

Key points:

  • Population: CANVAS-COVID captures safety data in a more diverse and representative population than in vaccine clinical trials, such as immunocompromised and pregnant and/or lactating people, who were excluded from the trials.
  • Location: Individuals are recruited from six provinces (British Columbia, Alberta, Nova Scotia, Ontario, Prince Edward Island, and Quebec) and one territory (Yukon), accounting for over 75% of Canada’s geography.
  • Participants: Both vaccinated and unvaccinated individuals are invited to participate. Electronic consent is given before each survey.
    • Vaccinated individuals are recruited via (1) posters/brochures provided at the time of vaccination, (2) electronic invitations from the vaccine booking site, and (3) email from the contact information saved in provincial vaccine registries, depending on the locale.

Those who volunteer and give their consent receive surveys via email one week after their first dose, one week after their second dose, with a follow up questionnaire seven months after the first dose.

  • Not yet vaccinated individuals are recruited via (1) existing CANVAS participants, (2) the CANimmunize platform, (3) the CANVAS-COVID webpage, (4) other volunteer research databases.
  • Volunteers who consent receive surveys sent via email seven days, 28 days, and six months following their recruitment.

Participants in the unvaccinated segment who subsequently get vaccinated are then recategorized among the vaccinated.

  • Questionnaires: These surveys capture basic demographic data, COVID-19 history, pregnancy or breastfeeding status, general health status, frailty status, whether the subject is immunocompromised, and tracks signs of worsening health following each vaccine dose (if applicable). Each health issue that is reported and required medical attention is followed-up via phone to obtain more details.
  • Measurements: The number, percentage, rate of health events per 10,000 people, and the rate of these events are calculated by type of health event, vaccine product, biological sex, and 10-year age brackets.
  • Knowledge translation: Weekly reports of preliminary results are shared confidentially with public health officials to ensure prompt safety signal detection. Preliminary findings are also updated frequently on the study website: