Improving public health policy through infection transmission modelling: Guidelines for creating a Community of Practice.

BACKGROUND: Despite significant research efforts in Canada, real application of modelling in public health decision making and practice has not yet met its full potential. There is still room to better address the diversity of the Canadian population and ensure that research outcomes are translated for use within their relevant contexts. OBJECTIVES: To strengthen connections to public health practice and to broaden its scope, the Pandemic Influenza Outbreak Research Modelling team partnered with the National Collaborating Centre for Infectious Diseases to hold a national workshop. Its objectives were to: understand areas where modelling terms, methods and results are unclear; share information on how modelling can best be used in informing policy and improving practice, particularly regarding the ways to integrate a focus on health equity considerations; and sustain and advance collaborative work in the development and application of modelling in public health. METHOD: The Use of Mathematical Modelling in Public Health Decision Making for Infectious Diseases workshop brought together research modellers, public health professionals, policymakers and other experts from across the country. Invited presentations set the context for topical discussions in three sessions. A final session generated reflections and recommendations for new opportunities and tasks. CONCLUSIONS: Gaps in content and research include the lack of standard frameworks and a glossary for infectious disease modelling. Consistency in terminology, clear articulation of model parameters and assumptions, and sustained collaboration will help to bridge the divide between research and practice.

HISTORIQUE: Malgré l'ampleur des recherches au Canada, la mise en œuvre de la modélisation n'a pas encore atteint son plein potentiel en santé publique dans la prise de décision et la pratique. Il y a matière à mieux intégrer la diversité de la population canadienne et d'utiliser les résultats de la recherche dans les contextes pertinents. OBJECTIFS: Pour renforcer les liens avec l'exercice de la santé publique et en élargir la portée, l'équipe de Pandemic Influenza Outbreak Research Modelling s'est associée au Centre de collaboration nationale des maladies infectieuses pour organiser un atelier national. Cet atelier visait à déterminer les secteurs où la terminologie, les méthodo-logies et les résultats de la modélisation manquent de clarté, à transmettre de l'information sur l'utilisation optimale de la modélisation pour étayer les politiques et améliorer la pratique, notamment en accordant plus d'importance aux questions d'équité en santé, et à maintenir et faire progresser la collaboration pour élaborer et mettre en œuvre la modélisation en santé publique. MÉTHODOLOGIE: L'atelier sur l'utilisation de la modélisation mathématique dans la prise de décision relative aux maladies infectieuses en santé publique a réuni des chercheurs modélisateurs, des professionnels de la santé publique, des décideurs et d'autres experts du pays. Les conférenciers ont mis en contexte les discussions dans le cadre de trois séances. Une dernière séance a suscité des réflexions et des recommandations sur les futures tâches et possibilités. CONCLUSIONS: Les lacunes en matière de contenu et de recherche incluent l'absence de cadres standardisés et de glossaire de la modélisation des maladies infectieuses. Une terminologie uniforme, la formulation claire des paramètres et des hypothèses de modélisation ainsi qu'une collaboration soutenue contribueront à corriger l'écart entre la recherche et la pratique.

Effectiveness of the pandemic H1N1 influenza vaccines against laboratory-confirmed H1N1 infections: population-based case-control study.

BACKGROUND: Excellent immune responses following 1 or 2 doses of the monovalent inactivated pandemic H1N1 vaccines have been documented, but the effectiveness of these vaccines against laboratory-confirmed H1N1 infections in the general population is not clear. We evaluated the effectiveness of the pandemic H1N1 and seasonal trivalent influenza vaccines (TIV) used during the 2009 mass vaccination campaign in Manitoba (Canada) in preventing laboratory-confirmed H1N1 infections. METHODS: A population-based case-control study using data from Cadham Provincial Laboratory (CPL) and the Manitoba Immunization Monitoring System (MIMS). All Manitoba residents ≥6 months of age who had a respiratory specimen tested at CPL for H1N1 were included in the study. Cases were individuals who tested positive for pandemic H1N1 influenza A by reverse transcriptase-PCR (N=1435). Controls were individuals who tested negative for both influenza A and B (N=2309). Information on receipt of TIV or H1N1 vaccine was obtained by record linkage with MIMS, the population-based province-wide immunization registry. RESULTS: Overall, the adjuvanted H1N1 vaccine was 86% (95%CI 75-93%) effective in preventing laboratory-confirmed H1N1 infections when vaccination occurred ≥14 days before testing. Effectiveness seemed lower among older (≥50 years) individuals [51% (-51 to 84%)] and among those with immunocompromising conditions [67% (-13 to 90%)]. There was also evidence that the H1N1 vaccine might be less effective among those who had received the 2009/10 TIV. DISCUSSION: The adjuvanted H1N1 vaccine used during Manitoba's H1N1 mass vaccination campaign was highly effective against laboratory-confirmed pandemic H1N1 infection, especially among children and younger adults.

Correlates of severe disease in patients with 2009 pandemic influenza (H1N1) virus infection.

BACKGROUND: In the context of 2009 pandemic influenza (H1N1) virus infection (pandemic H1N1 influenza), identifying correlates of the severity of disease is critical to guiding the implementation of antiviral strategies, prioritization of vaccination efforts and planning of health infrastructure. The objective of this study was to identify factors correlated with severity of disease in confirmed cases of pandemic H1N1 influenza. METHODS: This cumulative case-control study included all laboratory-confirmed cases of pandemic H1N1 influenza among residents of the province of Manitoba, Canada, for whom the final location of treatment was known. Severe cases were defined by admission to a provincial intensive care unit (ICU). Factors associated with severe disease necessitating admission to the ICU were determined by comparing ICU cases with two control groups: patients who were admitted to hospital but not to an ICU and those who remained in the community. RESULTS: As of Sept. 5, 2009, there had been 795 confirmed cases of pandemic H1N1 influenza in Manitoba for which the final treatment location could be determined. The mean age of individuals with laboratory-confirmed infection was 25.3 (standard deviation 18.8) years. More than half of the patients (417 or 52%) were female, and 215 (37%) of 588 confirmed infections for which ethnicity was known occurred in First Nations residents. The proportion of First Nations residents increased with increasing severity of disease (116 [28%] of 410 community cases, 74 [54%] of 136 admitted to hospital and 25 [60%] of 42 admitted to an ICU; p<0.001), as did the presence of an underlying comorbidity (201 [35%] of 569 community cases, 103 [57%] of 181 admitted to hospital and 34 [76%] of 45 admitted to an ICU; p<0.001). The median interval from onset of symptoms to initiation of antiviral therapy was 2 days (interquartile range, IQR 1-3) for community cases, 4 days (IQR 2-6) for patients admitted to hospital and 6 days (IQR 4-9) for those admitted to an ICU (p<0.001). In a multivariable logistic model, the interval from onset of symptoms to initiation of antiviral therapy (odds ratio [OR] 8.24, 95% confidence interval [CI] 2.82-24.1), First Nations ethnicity (OR 6.52, 95% CI 2.04-20.8) and presence of an underlying comorbidity (OR 3.19, 95% CI 1.07-9.52) were associated with increased odds of admission to the ICU (i.e., severe disease) relative to community cases. In an analysis of ICU cases compared with patients admitted to hospital, First Nations ethnicity (OR 3.23, 95% CI 1.04-10.1) was associated with increased severity of disease. INTERPRETATION: Severe pandemic H1N1 influenza necessitating admission to the ICU was associated with a longer interval from onset of symptoms to treatment with antiviral therapy and with the presence of an underlying comorbidity. First Nations ethnicity appeared to be an independent determinant of severe infection. Despite these associations, the cause and outcomes of pandemic HINI influenza may involve many complex and interrelated factors, all of which require further research and analysis.