National Advisory Committee On Immunization Research Articles

Summary of the National Advisory Committee on Immunization (NACI) Updated Guidance on Influenza Vaccination During Pregnancy.

Seasonal influenza infection can lead to serious complications and adverse outcomes for pregnant individuals, the developing fetus and infants younger than six months of age. This supplemental statement provides an evidence summary on the safety and effectiveness of influenza vaccination in pregnant individuals, and the benefits and risks to the pregnant person, the developing fetus and infants younger than six months of age. A systematic review was conducted on the effectiveness and safety of influenza vaccination in pregnancy. The National Advisory Committee on Immunization (NACI)'s evidence-based process was used to assess the quality of eligible studies, summarize and analyze the findings, and apply an ethics, equity, feasibility and acceptability lens to develop recommendations. The evidence suggests that influenza vaccination during pregnancy is effective in reducing the risk of laboratory-confirmed influenza infection and hospitalization in both pregnant individuals and their infants up to six months postpartum. The evidence also suggests that influenza vaccination during pregnancy does not increase the risk of non-obstetric serious adverse events in pregnant persons, infant death, spontaneous abortion, stillbirth, preterm birth, small for gestational age, low birth weight and congenital anomalies. Based on this body of evidence, NACI reaffirms the safety and importance of influenza vaccination during pregnancy. NACI recommends that individuals at any stage of pregnancy should receive an age-appropriate inactivated, unadjuvanted or recombinant influenza vaccine each influenza season. Influenza vaccination may be given at the same time as, or at any time before or after administration of another vaccine, including the coronavirus disease 2019 (COVID-19) or pertussis vaccines.

PP07 Vaccine Decision-making In Canada: Processes And Guidelines For Using Economic Evidence

IntroductionCanada’s National Advisory Committee on Immunization (NACI) makes recommendations on the use of human vaccines. Provinces and territories subsequently use the advice to make decisions on public funding and program implementation. Traditionally, NACI reviewed vaccine characteristics and burden of illness.With its recent expanded mandate, NACI now considers cost-effectiveness via economic evaluations, among other decision determinants. As such, new processes and guidelines were needed to formalize the incorporation of economic evidence into federal vaccine decision-making.MethodsTwo task groups were convened respectively to develop NACI’s “Economic Process” and “Guidelines for the Economic Evaluation of Vaccination Programs in Canada”. The groups conducted environmental scans to inform their work, as well as engaged with government partners, decision-makers, academics, national immunization technical advisory groups from other countries, health technology assessment agencies, industry, patient groups, among others.ResultsThe Economic Process outlines when and how NACI incorporates economic evidence for vaccine recommendation. For instance, it describes how policy questions are prioritized given institutional capacity constraints for generating economic evidence. It also describes how policy questions are assessed to determine the appropriate type of economic evidence required (i.e., systematic review, economic evaluation, multi-model comparison of external models).The Economic Guidelines provide recommendations in 15 chapters on how to conduct economic evaluations (i.e., from defining the decision problem to reporting). Unlike other health technologies, vaccines have the potential to affect both vaccinated and unvaccinated individuals. Hence, the Guidelines consider population-level impacts such as externalities (e.g., herd immunity, age-shifting of disease) and spillover effects. They also discuss equity considerations and non-health impacts of vaccines such as to productivity, consumption and education.ConclusionsThe Economic Process and Economic Guidelines promote the generation and use of credible and standardized economic evidence. They advocate for transparency, allowing evidence to be used across jurisdictions beyond Canada. Next steps include documentation of user feedback, incorporation of Indigenous considerations, and formal evaluations.

Summary of the National Advisory Committee on Immunization (NACI) Seasonal Influenza Vaccine Statement for 2023-2024.

The National Advisory Committee on Immunization (NACI) reviews the evolving evidence on influenza immunization and provides annual recommendations regarding the use of seasonal influenza vaccines. The NACI Statement on Seasonal Influenza Vaccine for 2023-2024 updates the 2022-2023 NACI recommendations. To summarize the 2023-2024 NACI seasonal influenza vaccine recommendations and to highlight new and updated information. In the preparation of the Statement on Seasonal Influenza Vaccine for 2023-2024, the NACI Influenza Working Group applied the NACI evidence-based process to critically appraise the available evidence and to propose recommendations. The recommendations were then considered and approved by NACI in light of the available evidence. Key changes for the 2023-2024 season include: 1) incorporation of updated information/guidance on influenza vaccination in the context of the coronavirus disease 2019 (COVID-19); 2) new recommendations for Flucelvax® Quad and Influvac® Tetra, the two quadrivalent inactivated influenza vaccines with expanded paediatric age indications; and 3) an update to the format of the Statement. Overall, NACI continues to recommend that an age-appropriate influenza vaccine should be offered annually to all individuals aged six months and older who do not have a contraindication to the vaccine, with particular focus on the groups for whom influenza vaccination is particularly recommended.

A National Advisory Committee on Immunization (NACI) update on invasive meningococcal disease (IMD) epidemiology and program-relevant considerations for preventing IMD in individuals at high risk of exposure.

Following recent outbreaks of invasive meningococcal disease (IMD) in Canada and updates to provincial vaccination guidelines, the National Advisory Committee on Immunization (NACI) conducted a targeted review of evidence with a focus on immunization of adolescents and young adults. NACI reviewed national and international immunization recommendations for populations at high-risk of IMD, national IMD epidemiology and program-relevant considerations. Given the varied IMD epidemiology, NACI determined that recommending a pan-Canadian targeted program is currently challenging and that regional programs may be better suited to prevent IMD in population groups considered to be at high-risk of exposure. Further data is needed to ascertain contemporary risk factors for IMD (including activities and settings associated with bacterial acquisition, carriage and transmission) and estimate the true cost of meningococcal vaccine-preventable infections in Canada. To support provinces and territories in their decision-making, an outline of program-relevant elements for provincial and territorial consideration is provided.

Impact of national recommendations for routine pertussis vaccination during pregnancy on infant pertussis in Ontario, Canada: a population-based time-series study

BackgroundIn February 2018, Canada’s National Advisory Committee on Immunization (NACI) recommended antenatal tetanus–diphtheria–acellular pertussis (Tdap) immunization in every pregnancy regardless of previous Tdap immunization history. We examined the impact of the NACI recommendation on rates of infant pertussis in Ontario, Canada.MethodsWe conducted a population-based time-series study of all live births in Ontario between August 1, 2011 and February 28, 2020. We used interventional autoregressive integrated moving average models to examine the impact of the NACI recommendation on monthly rates of pertussis among infants ≤ 3 months of age.ResultsWe observed 675 incident cases of pertussis among 1,368,024 infants 3 months of age or less between August 2011 and February 2020. The average monthly percent change in infant pertussis during the period up to and including publication of the NACI guidance and the period following publication were 0.0% (95% CI: -0.4–0.3%) and − 0.8% (95% CI -2.3% to -0.1%), respectively. Following interventional ARIMA modelling, publication of the NACI guidance was not associated with a statistically significant decrease in the monthly pertussis incidence trend (-0.67 cases per 100,000 infants; p = 0.73).ConclusionPublication of national recommendations for antenatal Tdap immunization in every pregnancy did not significantly reduce infant pertussis rates. This may reflect the persistently low rate of antenatal vaccination following publication of the recommendations. Expanding the scope of practice of allied health care providers to include antenatal Tdap immunization and patient education regarding antenatal pertussis immunization should be considered to further optimize uptake of vaccination.

Canada’s National Advisory Committee on immunization: Adaptations and challenges during the COVID-19 pandemic

The COVID-19 pandemic has challenged traditional vaccine guidance infrastructure and frameworks, and added urgency and complexity to the operation of National Immunization Technical Advisory Groups (NITAGs).Canada’s National Advisory Committee on Immunization (NACI) provides immunization guidance to the Public Health Agency of Canada (PHAC) who publicly shares expert and evidence-informed guidance with Canadian provinces and territories. Throughout the pandemic, NACI and PHAC implemented many adaptations to meet urgent needs for pandemic vaccine guidance.In this paper, we describe: structural adaptations in response to the accelerated pace and amount of work required to issue recommendations that were timed around product authorizations and dynamic epidemiology; technical adaptations in response to rapidly evolving evidence of variable quality which required close monitoring, and which promoted reliance on basic vaccine principles due to incomplete direct evidence; the need to provide nimble advice (e.g., off-label recommendations, preferential recommendations); communications adaptations (e.g. identify sustainable spokespeople for the committee, receive stakeholder feedback, and ensure urgent nuanced advice was communicated to a diverse audience); and research adaptations focussing on solutions to constrained supply (e.g. prioritisation, extended intervals, and heterologous schedules). The early pandemic vaccine experience has created a roadmap of lessons and adaptations that should be leveraged in future pandemic vaccine programs, and has highlighted the essential role of NITAGs to complement regulatory structures during pandemics to ensure timely, impactful, and evidence-informed public health vaccine guidance.

Young Investigator Interview with CSCI Distinguished Scientist Awardee Dr. Caroline Quach-Thanh.

Dr. Caroline Quach-Thanh is a Professor in the Departments of Microbiology, Infectious Diseases and Immunology and of Pediatrics at University of Montreal. She is in charge of Infection Prevention and Control at CHU Sainte-Justine where she works as a pediatric infectious diseases specialist and medical microbiologist. Dr. Quach is a clinician-scientist and the Canada Research Chair, Tier 1 in Infection Prevention and Control. In 2022, Dr. Quach-Thanh received the Distinguished Scientist Award 2022 from the Canadian Society for Clinical Investigation. In the same year, she received a Women of Distinction Award-for public service-from the Women's Y Foundation. Dr. Quach-Thanh is the former president from the Association for Medical Microbiology and Infectious Diseases Canada (AMMI), a past Chair of the National Advisory Committee on Immunization (NACI) and is the current chair of the Quebec Immunization Committee. She was named Fellow of the Canadian Academy of Health Sciences and of the Society for Healthcare Epidemiology of America. Dr. QuachThanh was selected as one of the 2019 most Powerful Women in Canada. In 2021, she received the Order of Merit from Université de Montréal and was made Officière de l'Ordre national du Québec in 2022.

EE211 Guidelines for the Economic Evaluation of Vaccination Programs in Canada

Canada’s National Advisory Committee on Immunization (NACI) makes recommendations on the use of human vaccines. Traditionally, NACI reviewed vaccine characteristics and disease burden. With its expanded mandate, NACI now considers cost-effectiveness via economic evaluations; thus, warranting guidelines. Existing guidelines are either not specific to the universal healthcare context, or not specific to vaccination programs.

Summary of the National Advisory Committee on Immunization (NACI) Statement-Recommendation on Repeated Seasonal Influenza Vaccination.

Influenza vaccination is recommended annually; however, some studies have raised questions regarding whether repeated influenza vaccine administration may have unintended negative consequences for seasonal protection. The National Advisory Committee on Immunization (NACI) Influenza Working Group undertook an overview of systematic reviews on the effects of repeated influenza vaccination on vaccine effectiveness, efficacy, and immunogenicity. A systematic assessment of programmatic factors was conducted according to established NACI methods. The NACI evidence-based process was used to critically appraise the available evidence and to review recommendations. The evidence base consisted of four eligible systematic reviews/meta-analyses. Repeated vaccination, including the current season, was consistently more effective than no vaccination in the current season. The evidence showed no significant difference or predictable trend in vaccine efficacy or effectiveness between vaccinations in two consecutive seasons compared to vaccination in the current season only. Overall, NACI concluded that there is evidence to recommend annual influenza vaccination, irrespective of whether an individual received the seasonal influenza vaccine in previous seasons. It is neither currently feasible nor warranted to modify existing annual influenza vaccination programs to account for potential negative or positive interference. NACI continues to strongly recommend that seasonal influenza vaccine should be offered annually to everyone six months of age and older who does not have contraindications to the vaccine, irrespective of previous seasons' influenza vaccination status.

Summary of the National Advisory Committee on Immunization (NACI) Statement-Recommendations on Fractional Influenza Vaccine Dosing in the Event of a Shortage: Pandemic preparedness.

At the commencement of a pandemic, it is important to consider the impact of respiratory infections on the health system and the possibility of vaccine shortages due to increased demand. In the event of an influenza vaccine shortage, a strategy for administration of fractional influenza vaccine doses might be considered. This article reviews the available evidence for efficacy, effectiveness, immunogenicity and safety of fractional influenza vaccine dosing, and summarizes the National Advisory Committee on Immunization (NACI) recommendations on fractional dosing strategies by public health programs in Canada. Two rapid literature reviews were undertaken to evaluate the efficacy, effectiveness, immunogenicity and safety of fractional influenza vaccine dosing via the intramuscular or intradermal route. The NACI evidence-based process was used to assess the quality of eligible studies, summarize and analyze the findings, and apply an ethics, equity, feasibility and acceptability lens to develop recommendations. There was limited evidence for the effectiveness of fractional influenza vaccine dosing. Fractional dosing studies were primarily conducted in healthy individuals, mainly young children and infants, with no underlying chronic conditions. There was fair evidence for immunogenicity and safety. Feasibility issues were identified with intradermal use in particular. NACI recommended that, in the event of a significant population-level shortage of influenza vaccine, a full-dose influenza vaccine should continue to be used, and existing vaccine supply should be prioritized for those considered to be at high risk or capable of transmitting to those at high risk of influenza-related complications or hospitalizations. NACI recommended against the use of fractional doses of influenza vaccine in any population.

Validation and Establishment of the SARS-CoV-2 Lentivirus Surrogate Neutralization Assay as a Prescreening Tool for the Plaque Reduction Neutralization Test.

Neutralization assays are important for understanding and quantifying neutralizing antibody responses toward severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 lentivirus surrogate neutralization assay (SCLSNA) can be used in biosafety level 2 (BSL-2) laboratories and has been shown to be a reliable alternative approach to the plaque reduction neutralization test (PRNT). In this study, we optimized and validated the SCLSNA to assess its ability as a comparator and prescreening method to support the PRNT. Comparability between the PRNT and SCLSNA was determined through clinical sensitivity and specificity evaluations. Clinical sensitivity and specificity assays produced acceptable results, with 100% (95% confidence interval [CI], 94% to 100%) specificity and 100% (95% CI, 94% to 100%) sensitivity against ancestral Wuhan spike-pseudotyped lentivirus. The sensitivity and specificity against B.1.1.7 spike-pseudotyped lentivirus were 88.3% (95% CI, 77.8% to 94.2%) and 100% (95% CI, 94% to 100%), respectively. Assay precision measuring intra-assay variability produced acceptable results for high (50% PRNT [PRNT50], 1:≥640), mid (PRNT50, 1:160), and low (PRNT50, 1:40) antibody titer concentration ranges based on the PRNT50, with coefficients of variation (CVs) of 14.21%, 12.47%, and 13.28%, respectively. Intermediate precision indicated acceptable ranges for the high and mid concentrations, with CVs of 15.52% and 16.09%, respectively. However, the low concentration did not meet the acceptance criteria, with a CV of 26.42%. Acceptable ranges were found in the robustness evaluation for both intra-assay and interassay variability. In summary, the validation parameters tested met the acceptance criteria, making the SCLSNA method fit for its intended purpose, which can be used to support the PRNT. IMPORTANCE Neutralization studies play an important role in providing guidance and justification for vaccine administration and helping prevent the spread of diseases. The neutralization data generated in our laboratory have been included in the decision-making process of the National Advisory Committee on Immunization (NACI) in Canada. During the coronavirus 2019 (COVID-19) pandemic, the plaque reduction neutralization test (PRNT) has been the gold standard for determining neutralization of SARS-CoV-2. We validated a SARS-CoV-2 lentivirus surrogate neutralization assay (SCLSNA) as an alternative method to help support the PRNT. The advantages of using the SCLSNA is that it can process more samples, is less tedious to perform, and can be used in laboratories with a lower biosafety level. The use of the SCLSNA can further expand our capabilities to help fulfill the requirements for NACI and other important collaborations.

Summary of the National Advisory Committee on Immunization (NACI) Rapid Response: Updated interim guidance on Imvamune in the context of ongoing monkeypox outbreaks.

During the period of monkeypox community transmission and restricted vaccine supply in the summer of 2022, Canadian provinces and territories and a number of vaccine stakeholders indicated the need for consistent national guidance on pre-exposure vaccination (including the identification of priority populations for pre-exposure vaccination programs) and guidance on the potential use of dose-sparing strategies. The National Advisory Committee on Immunization (NACI) High Consequence Infectious Disease Working Group reviewed data on the status of the monkeypox outbreak along with additional published and non-published evidence regarding the safety, immunogenicity and protection offered by Imvamune®. NACI approved updated recommendations on September 16, 2022, and on September 23, 2022 it released updated interim guidance on the use of Imvamune in the context of the ongoing monkeypox outbreak. During periods of adequate vaccine supply, NACI recommended that Imvamune pre-exposure vaccination should be offered as a two-dose primary series, with at least 28 days between the two sub-cutaneous doses. When supply is limited, guidance was provided for the use of dose sparing strategies, including extended dosing intervals and fractional intradermal dosing to maximize vaccine coverage for those at highest risk of exposure to the monkeypox virus. The updated NACI recommendations provide additional guidance on the use of Imvamune for the management of the 2022 monkeypox outbreak in Canada and may be considered to maximize vaccine coverage in outbreak settings when supply is limited.

NACI greenlights second doses, dose splitting of monkeypox vaccine.

Canada’s National Advisory Committee on Immunization (NACI) is strongly recommending “dose sparing strategies” to offer more people the monkeypox vaccine, including second doses. Imvamune, the only monkeypox vaccine available in Canada, normally should be given subcutaneously in two doses, 28

Trends and characteristics of Tdap vaccination during pregnancy in Ontario, Canada: a retrospective cohort study.

In February 2018, Canada's National Advisory Committee on Immunization (NACI) recommended tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccination during pregnancy to protect newborns against pertussis infection. We sought to describe pre- and postrecommendation trends in Tdap vaccination coverage among pregnant Ontario residents. Using linked health administrative databases, we conducted a population-based retrospective cohort study of all pregnant individuals who gave birth in Ontario hospitals between April 2012 and March 2020. We described Tdap vaccination patterns in pregnancy for the entire study period and before and after the NACI recommendation. We used log-binomial regression to identify characteristics associated with Tdap vaccination during pregnancy. Among the 991 850 deliveries included, 7.0% of pregnant individuals received the Tdap vaccination during pregnancy. Vaccine coverage increased from 0.4% in 2011/12 to 29.2% in 2019/20. Coverage was highest among individuals who were older, had no previous live births, had adequate prenatal care and received maternity care primarily from a family physician. After adjustment, characteristics associated with lower coverage included younger maternal age, having a multiple birth, residing in a rural location and higher area material deprivation. In 2019/20, 71.0% of vaccinated individuals received the Tdap vaccination during the recommended gestational window (27-32 wk). Stratified analyses of the pre- and postrecommendation cohorts yielded similar findings to the main analyses with a few gradient differences after adjustment. During pregnancy, Tdap vaccination coverage increased substantially in Ontario between 2011/12 and 2019/20, most notably after recommendations for universal Tdap vaccination during pregnancy began in Canada. To further improve vaccine coverage in the obstetric setting, public health strategies should consider tailoring their programs to reach subpopulations with lower vaccine coverage.

Summary of the National Advisory Committee on Immunization (NACI) Supplemental Statement on Recombinant Influenza Vaccines

Summary of the National Advisory Committee on Immunization (NACI) Supplemental Statement on Recombinant Influenza Vaccines

Summary of the National Advisory Committee on Immunization (NACI) Seasonal Influenza Vaccine Statement for 2022–2023

Summary of the National Advisory Committee on Immunization (NACI) Seasonal Influenza Vaccine Statement for 2022–2023

Summary of the National Advisory Committee on Immunization (NACI) Rapid Response-Interim guidance on the use of Imvamune in the context of monkeypox outbreaks in Canada.

Monkeypox is endemic in Central and West Africa. Cases in non-endemic countries, including Canada, have been increasing since May 2022. Imvamune®, a live, non-replicating smallpox vaccine, was approved by Health Canada for active immunization against smallpox and monkeypox infections and disease in adults determined to be at high risk for exposure. The aim of this interim guidance is to consider the use of Imvamune for post-exposure prophylaxis (PEP) and to summarize the available evidence in support of Imvamune use in this specific current context. The National Advisory Committee on Immunization (NACI) High Consequence Infectious Disease Working Group (HCID WG) reviewed data on the current status of the monkeypox outbreak, along with additional evidence included in published scientific literature and from manufacturers, regarding the safety, immunogenicity and protection offered by Imvamune. NACI approved these HCID WG recommendations on June 8, 2022. In brief, NACI recommends that PEP, using a single dose of the Imvamune vaccine, may be offered to individuals with high-risk exposures to a probable or confirmed case of monkeypox, or within a setting where transmission is happening. After 28 days, if an individual is assessed as having a predictable ongoing risk of exposure, a second dose may be offered. Imvamune may be offered to special populations; including individuals who are immunosuppressed, pregnant, breastfeeding, younger than 18 years of age and/or with atopic dermatitis. NACI has rapidly developed guidance on the use of Imvamune in Canada in the context of many uncertainties. Recommendations may be revisited as new evidence emerges.

Summary of the National Advisory Committee on Immunization (NACI) statement update on the recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants.

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in young children worldwide. Underlying health conditions, especially premature birth, chronic lung disease and congenital heart disease, predispose to severe RSV illness. The only means of prophylaxis against RSV disease is passive prophylaxis with the monoclonal antibody, palivizumab (PVZ) (SynagisTM). The National Advisory Committee on Immunization (NACI) published a statement for PVZ use in 2003. The purpose of this article is to update previous NACI recommendations for the use of PVZ, taking into consideration recent data on RSV burden of illness, effectiveness of PVZ in infants at risk of more severe RSV disease and economic implications of PVZ use. The NACI Working Group and external experts performed systematic literature reviews on three topics to support updated NACI guidance: 1) RSV burden of disease; 2) PVZ effectiveness; and 3) cost effectiveness of PVZ prophylaxis. Full details and results are presented in the statement and supporting documents. Respiratory syncytial virus hospitalization (RSVH) rates are highest in children younger than one year of age and especially in the first two months of life. In various populations of infants at risk of severe RSV infection, PVZ prophylaxis is associated with reductions of 38%-86% in the risk of RSVH. Only rare cases of anaphylaxis have been reported after decades of use. Palivizumab is expensive and only cost-saving in rare scenarios. Updated NACI recommendations on use of PVZ for the prevention of complications of RSV in infants are now available.

Sommaire de la mise à jour de la déclaration du Comité consultatif national de l'immunisation (CCNI) sur l'utilisation recommandée du palivizumab pour réduire les complications de l'infection par le virus respiratoire syncytial chez les nourrissons

Mise à jour des recommandations du CCNI concernant l’utilisation, l’efficacité et les répercussions économiques du palivizumab en raison des données récentes sur le fardeau du virus respiratoire syncytial.

Sommaire de la réponse rapide du Comité consultatif national de l'immunisation (CCNI) : Orientations provisoires sur l'utilisation d'Imvamune dans le contexte des éclosions de variole simienne au Canada

Sommaire de la réponse rapide du Comité consultatif national de l'immunisation (CCNI) : Orientations provisoires sur l'utilisation d'Imvamune dans le contexte des éclosions de variole simienne au Canada