Initial Guidance on a Second Booster Dose of COVID-19 Vaccines in CanadaSummary of NACI rapid response of April 5, 2022. Post author By National Advisory Committee on Immunization (NACI) Post date 5 April 2022 ← Recommendations on the use of Medicago COVID-19 vaccine (Covifenz) → Recommendations on the use of Moderna Spikevax COVID-19 vaccine in children 6 to 11 years of age