Canada communicable disease report = Releve des maladies transmissibles au Canada最新文献

{"title":"Fifty years of the Canadian Field Epidemiology Program (1975-2025): Reflecting on the past, shaping the future.","authors":"Louis Wong, Anja Bilandzic, Kathleen Laberge","doi":"10.14745/ccdr.v52i78a01","DOIUrl":"10.14745/ccdr.v52i78a01","url":null,"abstract":"<p><p>Since 1975, the Canadian Field Epidemiology Program (CFEP) has strengthened Canada's public health capacity by training field epidemiologists through a two-year, service-oriented model that integrates formal learning with field placements and mentorship. Established at the request of the provinces and territories and modelled after the United States' Epidemic Intelligence Service, CFEP has evolved into a nationally distributed surge and analytic capability embedded across jurisdictions. Over five decades, trainees and alumni have supported outbreak and emergency response, strengthened surveillance systems, and produced applied evidence that has informed control measures and policy, spanning foodborne and environmental events, severe acute respiratory syndrome (SARS), H1N1, COVID-19, and emerging One Health threats. The CFEP's impact also reflects deliberate workforce development through structured mentorship, cohort-based learning, and alumni networks that extend expertise across federal, provincial, territorial, academic, and international settings. As public health risks grow more complex due to climate-related hazards, rapid digital change, and challenges to trust, this commentary argues that CFEP must remain adaptive, deepen cross-sector partnerships, and embed equity, reconciliation, and systems thinking to sustain Canada's health security over the next 50 years.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"7-8 ","pages":"273-277"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13592874/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149019394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"\"Those fires I had to work through was a learning\": An evaluation of the Eeyou Istchee Daily Smoke Monitoring Report.","authors":"Anna Jw Manore, Jason Coonishish, Isabelle Duguay, Colleen Fuller, Juliette Ottereyes","doi":"10.14745/ccdr.v52i78a08","DOIUrl":"https://doi.org/10.14745/ccdr.v52i78a08","url":null,"abstract":"<p><strong>Background: </strong>In 2023, Eeyou Istchee experienced a record-breaking forest fire season, causing unprecedented damage to interconnected land, ecosystems, and cultural infrastructure. Acute health impacts of forest fires can be severe, including respiratory and cardiovascular problems, and heat-related illness. From May 2023 to September 2023, the Cree Board of Health and Social Services of James Bay (CBHSSJB) shared verbal updates on smoke, fire, and heat at daily meetings with public health and broader emergency response partners. In 2024, CBHSSJB formalized these verbal updates into a daily written report, distributing publicly available information via email to inform a timely public health response.</p><p><strong>Objective: </strong>To evaluate the usefulness of the <i>Eeyou Istchee Daily Smoke Monitoring Report</i> (shortened to the \"Report\") following the first season of implementation and identify potential improvements.</p><p><strong>Methods: </strong>The evaluation was co-developed with key partners using participatory approaches, with evaluation objectives focusing on the Report's usefulness for decision-making with respect to smoke, fire, and heat. Key informant interviews (n=6) were carried out with Report recipients, and results were summarized using thematic analysis.</p><p><strong>Results: </strong>Recipients described the Report as useful and a source of reassurance about current conditions in Eeyou Istchee. Suggested improvements included the addition of more visuals, plainer language, and supporting recipients seeking additional information to complement the Report (i.e., more specific than daily updates at a regional level).</p><p><strong>Conclusion: </strong>Opportunities for improvement identified through this evaluation informed updates to the Report for 2025 and beyond, and may also be applied by other Indigenous organizations developing or enhancing their own environmental monitoring and reporting processes.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 7-8","pages":"319-327"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13599764/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149043188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Red Cross and Red Crescent Movement responses to viral hemorrhagic fever outbreaks: A mixed-method evaluation of information management practices for Safe and Dignified Burials.","authors":"Douglas Lau, Arwen Barr, Marguerite Gollish, Maria Munoz-Bertrand","doi":"10.14745/ccdr.v52i78a07","DOIUrl":"10.14745/ccdr.v52i78a07","url":null,"abstract":"<p><strong>Background: </strong>Ebola and Marburg are viral hemorrhagic fevers (VHFs) with pronounced epidemic potential. Safe and Dignified Burials (SDBs) are a key pillar of humanitarian responses to VHF outbreaks, with Red Cross and Red Crescent (RCRC) National Societies often supporting implementation. The SDB information management (IM) toolkit is a collection of tools and templates that provides guidance for SDB IM across the RCRC Movement.</p><p><strong>Objective: </strong>To identify lessons learned from the implementation of the SDB IM toolkit and the broader approach to SDB IM in the RCRC Movement, focusing on acceptability, simplicity, and flexibility.</p><p><strong>Methods: </strong>A sequential mixed-method study design was used, with preliminary findings from key informant interviews guiding development of a subsequent online survey. Procedures for SDB data collection, analysis, and reporting were reviewed, along with how these outputs informed operational decision-making.</p><p><strong>Results: </strong>Eight interviews and 208 survey responses were analyzed. Acceptability of SDB IM was generally high, though uneven awareness of the SDB IM toolkit and gaps in communicating the strategic value of SDB IM limited broader uptake. Simplicity was viewed favorably, with clearly established workflows and a phased approach to implementation; however, overly detailed guidance documents, limited IM-specific training and insufficient opportunities for hands-on data collection undermined ease of implementation. Flexibility was evident across outbreak settings, though limited analysis and reporting capacity within some National Societies reduced operational adaptability.</p><p><strong>Conclusion: </strong>While gaps remain, this evaluation highlights the role of SDB IM in supporting data-informed VHF outbreak responses. Strengthening coordination, increasing awareness, expanding IM capacity and supporting greater local ownership may further enhance readiness for future responses.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 7-8","pages":"312-318"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13599606/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149042690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strengthening radon surveillance in British Columbia: Insights from a qualitative evaluation of the British Columbia Radon Data Repository.","authors":"Bridget Irwin, Jiayun Angela Yao, David McVea","doi":"10.14745/ccdr.v52i78a03","DOIUrl":"10.14745/ccdr.v52i78a03","url":null,"abstract":"<p><strong>Background: </strong>Radon is a carcinogenic gas that is the leading environmental cause of lung cancer in non-smokers. While its health risks are well-known, exposure to radon is variable and hard to determine, impeding risk assessment and mitigation. The British Columbia Centre for Disease Control (BCCDC) operates the British Columbia Radon Data Repository (BCRDR) to aggregate radon test results in support of research and public health action. This study evaluates the BCRDR, focusing on its usefulness and acceptability to those who contribute to and use the repository.</p><p><strong>Methods: </strong>Between November 2024 and July 2025, five contributors of radon data to the BCRDR and six users of radon data from the BCRDR were interviewed. In addition, six data holders, five data users, and 74 members of the public completed web surveys. Interviews and surveys were analyzed qualitatively using inductive thematic content analysis to generate themes.</p><p><strong>Results: </strong>Overall, users and contributors find the BCRDR useful and acceptable. Contributing data holders described the data submission process as quick and easy, and felt that the BCCDC addressed concerns. The repository supported a wide range of uses by a variety of stakeholders, most of whom found the data valuable. Respondents provided recommendations to further strengthen the repository.</p><p><strong>Conclusion: </strong>The findings affirm the BCRDR's value for both those contributing data and those using it. Responses can inform enhancements to the existing provincial repository and guide the development of future radon surveillance systems as well.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 7-8","pages":"282-289"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13596081/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149027524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Developing and piloting an interactive syphilis surveillance dashboard through user-centred design: An implementation report from Interior Health, British Columbia.","authors":"Temuulen Enebish, Barbara Gauthier, Jonathan Malo","doi":"10.14745/ccdr.v52i78a06","DOIUrl":"https://doi.org/10.14745/ccdr.v52i78a06","url":null,"abstract":"<p><strong>Background: </strong>Syphilis rates have risen in Canada and British Columbia (BC), increasing the need for timely, small-area intelligence. In BC, 1,983 cases of infectious syphilis were reported in 2024, representing a rate of 34.8 cases per 100,000 population. An additional 27 cases of congenital syphilis were also confirmed. Routine quarterly reporting limits responsiveness when incidence shifts quickly.</p><p><strong>Objective: </strong>To describe the development, implementation, and early evaluation of an interactive surveillance dashboard for syphilis in Interior Health (IH), delivering monthly indicators at the Local Health Area (LHA) level.</p><p><strong>Methods: </strong>An internal dashboard was developed using user-centred design and iterative stakeholder engagement. The dashboard integrates case, testing, and denominator data to display monthly indicators, 12-month trends, and LHA-level patterns, with role-based access and privacy safeguards for authorized users.</p><p><strong>Results: </strong>Perceived usefulness, simplicity, and acceptability were assessed using Likert ratings and structured feedback. In a pilot with 11 users across key IH program groups, overall impression, ease of use, usefulness, and program fit were rated 5.0/5, 4.9/5, 4.9/5, and 4.6/5 (n=8-9). Users described value for prioritizing LHAs, planning interventions, and briefing decision-makers.</p><p><strong>Conclusion: </strong>An interactive, LHA-level dashboard was feasible within existing systems and acceptable to pilot users, with perceived improvements in timeliness and clarity. Effects on downstream public health outcomes remain to be evaluated. The approach may be transferable to similar jurisdictions.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 7-8","pages":"306-311"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13599605/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149042685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The evolution of applied field epidemiology training in Canada: The last fifty years, and a vision for the future.","authors":"Benjamin Hetman, Esmé Lanktree, Carolyn Dohoo, Joanne Stares, Marc-André Bélair, Lisa Jensen","doi":"10.14745/ccdr.v52i78a02","DOIUrl":"10.14745/ccdr.v52i78a02","url":null,"abstract":"<p><p>In Canada, successive crises (e.g., severe acute respiratory syndrome [SARS] in 2003, H1N1 in 2009, COVID-19 in 2019) have not only tested the response capacity of the public health workforce, but reshaped how field epidemiologists are trained. Over five decades, federal applied epidemiology training in Canada has evolved from a small, in-person program focused on outbreak investigation to a multidisciplinary, nationally coordinated training ecosystem integrating emergency management, health equity, climate responsiveness, and technological fluency. This commentary reflects on that evolution and considers the future of the Field Epidemiology Training Program in an era of intersecting and accelerating public health needs.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 7-8","pages":"278-281"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13596082/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149027513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mixed-methods evaluation and enhancement of Peel Public Health's heat-related illness emergency department visit surveillance system, 2018-2024.","authors":"Sean Colyer, Maureen Horn, Lydia Cheng, Jessica Deming, Monali Varia","doi":"10.14745/ccdr.v52i78a05","DOIUrl":"10.14745/ccdr.v52i78a05","url":null,"abstract":"<p><strong>Background: </strong>Climate change contributes to increased heat events, which are associated with negative health outcomes. Peel Public Health, a health unit in Ontario, has conducted emergency department (ED) visit surveillance during heat events since 2018 using Acute Care Enhanced Surveillance data.</p><p><strong>Objective: </strong>To optimize local public health surveillance of heat-related illnesses, a mixed-methods evaluation of system usefulness and representativeness was conducted and the system was enhanced through retrospective observational analyses.</p><p><strong>Methods: </strong>The surveillance usefulness was evaluated through semi-structured interviews with ten recipients of the surveillance product and representativeness by determining the impact of data by patient address compared to hospital address over 2018-2024. Retrospective analyses of 2018-2024 data identified associations between heat events and surveillance ED indicators. Findings informed surveillance revisions.</p><p><strong>Results: </strong>Interviewees interpreted the original surveillance product as a high-level real-time snapshot of downstream health outcomes, useful for situational awareness and understanding of whether ED visits were increasing. Recommendations included adding key messages, thresholds/ranges and subgroup information. Representativeness evaluation showed that 27.2% of ED visits by Peel residents were at non-Peel hospitals and 14.0% of Peel hospital ED visits were by non-Peel residents. Daily counts of heat-related illnesses were significantly associated with heat event days (incidence rate ratio: 6.43, 95% confidence interval: 3.86-10.71).</p><p><strong>Conclusion: </strong>A revised surveillance product was implemented for 2025 including standard deviations, aberration alerts adapted from preexisting criteria, ED visits based on hospital address and stratification by three subgroups (aged older than 65 years and younger than five years, and elevated heat vulnerability) to increase usefulness for situational awareness.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 7-8","pages":"299-305"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13597009/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149027500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wastewater surveillance as an early warning indicator for norovirus: Validating wastewater signals against clinical indicators in British Columbia, Canada, 2021-2025.","authors":"Bridget Irwin, Natalie Prystajecky, Mayank Singal, Sharon Relova, Anya Smith, David McVea","doi":"10.14745/ccdr.v52i78a04","DOIUrl":"10.14745/ccdr.v52i78a04","url":null,"abstract":"<p><strong>Background: </strong>Norovirus is the leading cause of acute gastroenteritis globally and causes significant morbidity. Despite this, norovirus is not reportable to the public health system in most jurisdictions, making it challenging to detect and control local transmission. Wastewater-based epidemiology is a potential tool for narrowing this gap, allowing for non-invasive, population-level surveillance.</p><p><strong>Objective: </strong>In this study, it assess wastewater-based epidemiology as a surveillance tool for monitoring norovirus in British Columbia, Canada, by comparing norovirus wastewater signals to norovirus-related hospital admissions and genogroup I (GI)-related emergency department (ED) visits.</p><p><strong>Methods: </strong>More than six thousand (n=6,167) wastewater samples from 12 municipal treatment plants were collected between January 10, 2021-September 27, 2025 and pooled to generate a population-weighted average for the province. Norovirus hospital admissions and GI-related ED visits were extracted for the same period from the Discharge Abstract Database and the National Ambulatory Care Reporting System, respectively, and were compared with wastewater signals using time-lagged cross-correlation analyses.</p><p><strong>Results: </strong>Time-lagged cross-correlation analyses indicate significant positive correlation overall between unadjusted norovirus wastewater concentrations and norovirus hospitalizations (Spearman's ρ=0.69, <i>p</i><0.01) and GI-related ED visits (Spearman's ρ=0.84, <i>p</i><0.01), with wastewater leading hospitalizations by two weeks (Spearman's ρ=0.71) and aligned with ED visits (Spearman's ρ=0.83).</p><p><strong>Conclusion: </strong>The findings support the validity of using wastewater-based epidemiology for monitoring norovirus at the population-level and suggest that it may provide an early warning signal for severe norovirus activity requiring hospitalization, prompting a more timely response.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 7-8","pages":"290-298"},"PeriodicalIF":0.0,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13596700/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149027498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics of outpatient nirmatrelvir/ritonavir recipients during the 2022/2023 era in Alberta, Canada: A retrospective observational population-based study.","authors":"Khanh Vu, Jason Randall, Karen Martins, Sylvia Aponte-Hao, Lynora Saxinger, Jenine Leal, Elissa Rennert-May, Ellen Rafferty, Phuong Uyen Nguyen, Tyler Williamson, Scott Klarenbach","doi":"10.14745/ccdr.v52i06a06","DOIUrl":"https://doi.org/10.14745/ccdr.v52i06a06","url":null,"abstract":"<p><strong>Background: </strong>An understanding of real-world nirmatrelvir/ritonavir (NMV-r; Paxlovid™) use in Canada is needed to inform strategies for therapy access and use.</p><p><strong>Objective: </strong>To describe the characteristics of adults who received NMV-r in Alberta, Canada.</p><p><strong>Methods: </strong>Population-level administrative data was used to describe adults (18 years and older) who received an outpatient dispensation of NMV-r between January 2022 and March 2023 in Alberta. Omicron variants predominated during this period.</p><p><strong>Results: </strong>Mean age of the cohort (n=11,793) was 65 years (standard deviation=18), 60.4% were female and 83.9% had one or more health condition associated with a risk for the development of severe COVID-19 outcomes. In comparison to the general Alberta population, a larger proportion of those that received NMV-r resided in urban areas (Alberta: 82.3%; NMV-r: 89.8%) and were more socioeconomically well-off (Material Deprivation Index quintile 1-Alberta: 20.0%; NMV-r: 25.8%). A total of 81.6% received three or more COVID-19 vaccine doses and 7.0% received one or no dose. The majority of dispensed NMV-r prescriptions were from physicians (83.6%), with 13.5% from pharmacists and 2.9% from other healthcare providers.</p><p><strong>Conclusion: </strong>In Alberta, adults who received outpatient NMV-r displayed characteristics associated with risk for progression to severe COVID-19 outcomes (related to age and health conditions) and healthcare-seeking behaviour (older age, female sex, presence of health conditions, higher socioeconomic status and highly vaccinated). Provision by urban/rural and socioeconomic status were noted. Findings can be used to inform strategies for overcoming barriers and ensuring equitable access to COVID-19 therapy for all who are most likely to benefit.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 6","pages":"264-272"},"PeriodicalIF":0.0,"publicationDate":"2026-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13488241/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148803764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intraseasonal waning of influenza vaccine effectiveness and implications for the optimal timing of seasonal vaccination programs: A scoping review.","authors":"Pamela Doyon-Plourde, Fazia Tadount, Anabel Gil, Calin Lazarescu, Marie-Michelle Ursu, Nadine Sicard, Winnie Siu, Angela Sinilaité","doi":"10.14745/ccdr.v52i06a03","DOIUrl":"10.14745/ccdr.v52i06a03","url":null,"abstract":"<p><strong>Background: </strong>Seasonal influenza vaccination programs aim to provide protection before the virus circulation begins. However, vaccine effectiveness (VE) may decline within a single influenza season due to waning immunity, antigenic drift, and season-specific factors, raising questions about optimal vaccination timing. The purpose of this review was to synthesize evidence on intraseasonal waning of seasonal influenza VE and examine the implications and key considerations for optimizing the timing of seasonal vaccination in Canada.</p><p><strong>Methods: </strong>A scoping review was conducted, with searches of MEDLINE, Embase, Scopus, Cochrane Library, and ProQuest Public Health Database that identified studies published from 2010 to June 2024, with an update in July 2025. Eligible studies included clinical trials, observational studies, systematic reviews, and modelling studies reporting at least two VE estimates by time since vaccination within a season or assessing vaccination timing and its impact on influenza outcomes.</p><p><strong>Results: </strong>Forty-nine studies met inclusion criteria, including 37 assessing intraseasonal waning and 12 examining vaccination timing. Overall, VE was generally highest within one to three months post-vaccination and declined over the season (e.g., three to six months post-vaccination). Waning was more consistently observed for influenza A, particularly A(H3N2), and among adults aged 60 years and older. Modelling studies suggested that delaying vaccination could reduce influenza burden under select late-peaking or fast-waning scenarios; however, estimated benefits were generally small and highly sensitive to assumptions.</p><p><strong>Conclusion: </strong>Intraseasonal waning of influenza VE is consistently observed, particularly for influenza A and in older adults, but represents a gradual decline that does not typically undermine season-long effectiveness. Evidence does not support substantial or consistent population-level benefits from delaying vaccination.</p>","PeriodicalId":94304,"journal":{"name":"Canada communicable disease report = Releve des maladies transmissibles au Canada","volume":"52 6","pages":"231-245"},"PeriodicalIF":0.0,"publicationDate":"2026-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13465922/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148727704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}