Thank you very much.
I would like to begin by thanking the Chair and the members of the Standing Committee on Health for inviting me to testify.
I am a pediatrician, a microbiologist-infectiologist and a clinical researcher at CHU Sainte-Justine, as well as a full professor in the Department of Microbiology, Infectiology and Immunology at the Université de Montréal. I have clinical and research expertise in infection control from hospital to community, which also includes vaccination. I hold a Tier 1 Canada Research Chair in infection prevention and control: hospital to community. However, I am testifying today as Chair of the National Advisory Committee on Immunization, or NACI, so I will limit myself to that committee's mandate.
The National Advisory Committee on Immunization, or NACI, is an external advisory committee to the Public Health Agency of Canada and has existed since l964.
The NACI work and committee attendance for the 15 voting members and the chair is done on a voluntary basis and carefully reviewed for any conflicts of interest.
NACI makes recommendations to the Public Health Agency of Canada on issues relating to immunization for the vast majority on vaccines that have been authorized by Health Canada. In only one instance was NACI asked to make recommendations on a not yet authorized vaccine to support emergency preparedness, the Ebola vaccine.
NACI bases its recommendations on various elements, including the burden of illness; vaccine characteristics such as safety, immunogenicity and efficacy; ethics; equity; feasibility and acceptability as well as economics.
To ensure that NACI has the proper expertise, it expanded its voting membership in recent years to include a social scientist, two health economists and an epidemiologist and consults regularly with the Public Health ethics consultative group.
NACI uses a systematic approach to review the medical literature and vaccine science, which may take longer to perform compared to a narrative review, but ensures reproducibility and quality so that provinces and territories are confident about the knowledge synthesis product they can then use for their local recommendations.
Given the growing need for recommendations with respect to vaccination against COVID-19, the NACI has increased the frequency of its meetings, sometimes to one per week. The secretariat supporting the NACI within the Public Health Agency has worked diligently to provide the NACI with the information it needed to make decisions, including scientific literature reviews, ethical analyses and management option tables. This has allowed for a variety of approaches based on provincial values and epidemiology.
Since the beginning of the pandemic, the NACI has issued a number of statements: a statement on research priorities to guide manufacturers' phase III randomized trials, so as to answer key questions that will enable the NACI to make recommendations on the use of vaccines for various populations, including vulnerable individuals; four recommendations on priority groups for vaccination in various circumstances; and two recommendations on the use of vaccines for COVID-19, including one for each of the vaccines approved by Health Canada.
Given the questions on variants asked by HESA and in keeping with the NACI mandate, I cannot comment on the vaccine rollout. However, NACI has variants of concern, VOCs, on its radar, having added many research questions over time in our recommendations on the use of COVID-19 vaccines; the latest version remains to be published. These research questions feed both the Canadian Immunization Research Network's work plan and the newly formed vaccine surveillance reference group, safety and effectiveness working groups, to identify knowledge gaps and leverage existing cohorts or surveillance infrastructure to answer these questions.
The following questions relate to VOCs: What is the role of humoral versus cellular immunity in preventing immune escape of viral variants? How will viral variants impact the efficacy, effectiveness, immunogenicity and safety of a vaccine with respect to death, severe illness, symptomatic disease, asymptomatic disease, infectivity and transmission? What is the effect of using booster vaccines containing heterologous antigens and what is the optimal timing for booster vaccination?
At this point, NACI has requested presentations of vaccine effectiveness data from the U.K. where the B.1.1.7 variant is the most predominant SARS-CoV-2, in a country where both AstraZeneca and Pfizer-BioNTech are used with an extended interval of 12 weeks. Data were presented to NACI confidentially on February 8, 2021, after four weeks of follow-up of individuals vaccinated with the Pfizer vaccine. Public Health England will be presenting an update on their results again next week at the regular NACI meeting.
Based on data from the literature, NACI considers that the available mRNA vaccines remain effective against the VOC that emerged in the U.K. Studies show that following one dose of the Pfizer-BioNTech, participants' sera exhibited a broad range of neutralizing titres against the wild-type virus that were only modestly reduced against the B.1.1.7 variant.
The introduction of the E484K mutation in a B.1.1.7 background led to a more substantial loss of neutralizing activity. Neutralizing antibodies were lower in those 80 years and over in a separate study. However, antibody response, as key as it may be, is not the only type of immunity that is of importance: cellular immunity also plays an important role in protecting the individual.
As there are no known correlates of protection, and as we are likely going to see the emergence of other new variants over time, it is paramount that Canada and the world invest in surveillance and tracking of variants, identifying those of concern; analyze new variants' sensitivity to neutralization by vaccine recipients' sera; study vaccine protection of animals against challenge with new strains, and sequence viruses causing breakthrough infections in vaccinees. This will allow for real-time vaccine effectiveness surveillance alongside VOC's identification and surveillance.
The spread of the VOC that emerged in South Africa, the B.1.351, may be more detrimental. Data from recent randomized clinical trials where VOCs were circulating showed that although these vaccines, the vector-based and Novavax, remained efficacious against the B.1.1.7 variant, they had decreased efficacy against the South African variant.
The phase 3 studies that were conducted for the mRNA vaccines were done at a time when VOCs were not yet prevalent. However, we are aware that some of the leading vaccine manufacturers are already working on new versions of their COVID-19 vaccines adjusted to target B.1.351 or other variants. NACI is monitoring the data and will issue a statement if a booster or a new dose is needed, including consideration of any new vaccine candidates that are authorized by Health Canada.
NACI is also monitoring the use of heterologous vaccine schedules. Preliminary results from an animal study showed that a combination of mRNA and AstraZeneca elicited a stronger cell-mediated immunity. The U.K. started a study whereby AstraZeneca and Pfizer will be administered as a mixed schedule. Recruitment started at the beginning of February, and NACI will be monitoring the results from this study.
For over 50 years, NACI has been providing evidence-informed, expert advice to the Government of Canada on vaccines. Viral variants or different strains of diseases are not a new phenomenon, and we have a long history of adapting vaccine programs to the changing evidence in areas such as influenza, where new vaccines are needed every year, or pneumococcal disease, where different strains have waxed and waned requiring dynamic vaccine technologies and program redesign over the years. NACI is poised to adjust this new vaccine program, if needed, as the evidence evolves.
I thank you for your attention and will be happy to answer questions as they relate to NACI's mandate.
