National Advisory Committee on Immunization

Did You Know?

• NACI is mandated to provide the Public Health Agency of Canada with advice on vaccine evaluation and monitoring of vaccine-associated adverse events.
• The committee's precursor was established in 1964.

History

The committee began in 1964 as the National Advisory Committee on Immunizing Agents, tasked with advising the Department of National Health and Welfare on immunizing agents. In 1975 its mandate shifted to focus on new vaccine introductions and immunization program development. It was renamed the National Advisory Committee on Immunization in 1978 to reflect its broader role in immunization procedures and coverage.

Membership

NACI comprises 14 voting members, including a chair and vice-chair, plus an executive secretary. It also includes roughly a dozen industry liaison representatives and roughly a dozen ex-officio professional public service representatives from Health Canada. Voting members are experts in fields such as immunization, public health, vaccine preventable diseases, pediatric or adult infectious diseases, and allergy/immunology.

COVID-19 pandemic

During the pandemic, NACI published recommendations and guidance on COVID-19 vaccine distribution, some of which drew criticism as counter-productive for public health and communications. In March 2021, amid supply shortages, NACI strongly recommended extending the interval between first and second doses of two-dose vaccines (AstraZeneca, Moderna, Pfizer) to up to four months, citing modelling that showed sustained high protection from the first dose. Pfizer Canada's president warned in the House of Commons that the real-world data used to support the extended schedule came from much younger populations and that no data existed beyond two months for one-dose protection. On May 28, citing improved vaccine availability, NACI recommended second doses be given as soon as possible, especially to high-risk individuals, while continuing to endorse the four-month interval for maximizing first-dose coverage. On May 4, 2021, NACI recommended that mRNA vaccines be preferred over viral vector vaccines (AstraZeneca, Janssen) due to the rare risk of vaccine-induced immune thrombotic thrombocytopenia. Vice-chairman Shelley Deeks stated that individuals should have an informed choice to receive the first available vaccine or wait for an mRNA vaccine. Some politicians and public health authorities argued this would encourage hesitancy and hinder rapid inoculation. On May 6, NACI clarified that its statement did not imply that taking AstraZeneca was a mistake and affirmed the vaccine's effectiveness against COVID-19.