Influenza In Canada Research Articles

Point-of-Care Tests for COVID-19 and Influenza in Canada

What Is the Issue? Health care providers rely on laboratory tests to differentiate between respiratory illnesses that manifest in similar symptoms, such as COVID-19 and influenza. However, samples may travel to centralized laboratories to process, delaying test results and treatment. Point-of-care tests (POCTs) allow for diagnosis at the site of care but at the expense of diagnostic performance. Several commercial POCTs, specifically for COVID-19, have become increasingly available in Canada since the start of the pandemic. Decision-makers will need to consider which commercial POCT can meet their jurisdiction’s testing needs. POCTs in Canada and their Potential Impact Some POCTs, called “Multiplex tests,” can detect and differentiate between certain illnesses using a single sample. Some studies suggest that using POCTs for respiratory illness in hospitals and emergency departments can expedite diagnosis, improve patient flow, reduce admissions, and shorten the length of stay. Commercial POCTs vary in diagnostic performance, complexity, and costs. There are at least 37 authorized POCTs for COVID-19, influenza, or both in Canada. All devices accept a nasal, nasopharyngeal sample, or both sample types for testing. Some tests require a reader or analyzer to use test kits for diagnosis. POCTs can provide results in 1 hour or less. However, laboratory testing (i.e., nucleic acid amplification tests) remains the standard of care to diagnose COVID-19 and influenza, given their better diagnostic performance compared to POCTs. What Else Do We Need to Know? Confirmatory laboratory tests can reaffirm the diagnosis from POCTs. However, budget impact analyses and clinical studies on authorized tests in Canada do not consider how confirmatory lab tests impact findings on POCT use. Future studies should investigate the cost-effectiveness of POCTs with confirmatory testing, as well as the impact of incorrect diagnosis from POCT on patient outcomes. Rural and remote communities may benefit from POCTs for respiratory illness, given their distance to centralized laboratories.

One Health communication channels: a qualitative case study of swine influenza in Canada in 2020

BackgroundWith increased attention to the importance of integrating the One Health approach into zoonotic disease surveillance and response, a greater understanding of the mechanisms to support effective communication and information sharing across animal and human health sectors is needed. The objectives of this qualitative case study were to describe the communication channels used between human and animal health stakeholders and to identify the elements that have enabled the integration of the One Health approach.MethodsWe combined documentary research with interviews with fifteen stakeholders to map the communication channels used in human and swine influenza surveillance in Alberta, Canada, as well as in the response to a human case of H1N2v in 2020. A thematic analysis of the interviews was also used to identify the barriers and facilitators to communication among stakeholders from the animal and human health sectors.ResultsWhen a human case of swine influenza emerged, the response led by the provincial Chief Medical Officer of Health involved players at various levels of government and in the human and animal health sectors. The collaboration of public and animal health laboratories and of the swine sector, in addition to the information available through the surveillance systems in place, was swift and effective. Elements identified as enabling smooth communication between the human and animal health systems included preexisting relationships between the various stakeholders, a relationship of trust between them (e.g., the swine sector and their perception of government structures), the presence of stakeholders acting as permanent liaisons between the ministries of health and agriculture, and stakeholders' understanding of the importance of the One Health approach.ConclusionsInformation flows through formal and informal channels and both structural and relational features that can support rapid and effective communication in infectious disease surveillance and outbreak response.

Strengthening a One Health approach to emerging zoonoses

Given the enormous global impact of the COVID-19 pandemic, outbreaks of highly pathogenic avian influenza in Canada, and manifold other zoonotic pathogen activity, there is a pressing need for a deeper understanding of the human-animal-environment interface and the intersecting biological, ecological, and societal factors contributing to the emergence, spread, and impact of zoonotic diseases. We aim to apply a One Health approach to pressing issues related to emerging zoonoses, and propose a functional framework of interconnected but distinct groups of recommendations around strategy and governance, technical leadership (operations), equity, education and research for a One Health approach and Action Plan for Canada. Change is desperately needed, beginning by reorienting our approach to health and recalibrating our perspectives to restore balance with the natural world in a rapid and sustainable fashion. In Canada, a major paradigm shift in how we think about health is required. All of society must recognize the intrinsic value of all living species and the importance of the health of humans, other animals, and ecosystems to health for all.

New Frontiers in the Control of Influenza

In normal times, the Canadian Immunization Conference (CIC) takes place every two years, bringing together public health officials, community advocates, and researchers and clinicians with an interest in vaccines and vaccine- preventable diseases. Due to the COVID-19 pandemic, the conference had not taken place in person since 2018 – in part due to restrictions on travel and gatherings, but also because many attendees were heavily involved in managing the most wide-ranging public health crisis of our time, including the largest mass vaccination campaign in human history. CIC 2023 was a long-awaited opportunity to appreciate the efforts and successes of the response to COVID-19, and to look ahead to how advances in vaccine technologies and improvements in public health processes might help us close a significant gap in immunizations against other vaccine-preventable diseases that occurred over those years. This report will focus on presentations and perspectives relevant to routine immunization programs against seasonal influenza in Canada.

Antigenic drift and epidemiological severity of seasonal influenza in Canada

Seasonal influenza epidemics circulate globally every year with varying levels of severity. One of the major drivers of this seasonal variation is thought to be the antigenic drift of influenza viruses, resulting from the accumulation of mutations in viral surface proteins. In this study, we aimed to investigate the association between the genetic drift of seasonal influenza viruses (A/H1N1, A/H3N2 and B) and the epidemiological severity of seasonal epidemics within a Canadian context. We obtained hemagglutinin protein sequences collected in Canada between the 2006/2007 and 2019/2020 flu seasons from GISAID and calculated Hamming distances in a sequence-based approach to estimating inter-seasonal antigenic differences. We also gathered epidemiological data on cases, hospitalizations and deaths from national surveillance systems and other official sources, as well as vaccine effectiveness estimates to address potential effect modification. These aggregate measures of disease severity were integrated into a single seasonal severity index. We performed linear regressions of our severity index with respect to the inter-seasonal antigenic distances, controlling for vaccine effectiveness. We did not find any evidence of a statistical relationship between antigenic distance and seasonal influenza severity in Canada. Future studies may need to account for additional factors, such as co-circulation of other respiratory pathogens, population imprinting, cohort effects and environmental parameters, which may drive seasonal influenza severity.

Projected impact of a plant-derived vaccine on the burden of seasonal influenza in Canada

ABSTRACT Objective The analysis estimates projected population outcomes resulting from the introduction of a plant-derived influenza vaccine formulated as quadrivalent virus-like particles (QVLP) in Canada. Methods Using Monte Carlo simulations, the number of influenza cases, general practitioner visits, inpatient admissions, intensive care unit (ICU) admissions, and deaths due to influenza-associated illness were estimated under no vaccination, plant-derived QVLP vaccines only, or egg-derived vaccines only. The base case analysis examined the adult Canadian population in two subgroups: 18–64 years of age during the 2017/18 season and 65+ years of age during the 2018/19 season. Efficacy data were obtained from QVLP clinical trials. Vaccine effectiveness data for egg-derived vaccines were calculated from observational studies from the corresponding influenza seasons. Scenario analyses examined the impact of varying absolute vaccine effectiveness or vaccination coverage from base case inputs. Results In the base case analysis, plant-derived QVLP vaccines led to an additional reduction in the burden of influenza over egg-derived vaccines for both population subgroups. In the 18–64 subgroup, QVLP vaccines were associated with 2.63% (48,029; 95% credible interval [Crl]: 42,723–53,336) fewer influenza cases than egg-derived vaccines. In the 65+ subgroup, QVLP vaccines led to 4.82% (27,918; 95% Crl: 25,440–30,397) fewer influenza cases, and reductions in the number of inpatient admissions by 4.77% (1167; 95% CrI: 851–1483) and deaths by 4.75% (326; 95% CrI: 107–546) compared to egg-derived vaccines. Further reductions were observed in scenario analyses considering the potential increase in vaccine coverage. Conclusion Use of plant-derived QVLP influenza vaccines may contribute to greater reductions in influenza cases and influenza-related outcomes, including inpatient admissions and deaths, compared to egg-derived vaccines currently available in Canada.

A modified TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) applied to choosing appropriate selection methods in ongoing surveillance for Avian Influenza in Canada

To achieve an appropriate and efficient sample in a surveillance program, the goals of the program should drive a careful consideration of the selection method or combination of selection methods to be applied. Therefore, the ongoing analysis and assessment of a surveillance system may include an assessment of the ability of the applied selection methods to generate an appropriate sample. There may be opinions from many technical experts (TEs) and many criteria to consider in a surveillance system so there is a need for methods to combine knowledge, priorities and preferences from a group of TEs.This paper proposes a modified weighted and unweighted TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) analysis to choose selection methods in surveillance. An example from the Canadian Notifiable Avian Influenza surveillance (CanNAISS) is used to illustrate the method as this surveillance offers unique data with multiple selection methods and subpopulations. The primary objective was to assess the performance of the different selection methods applied in CanNAISS, from 2008 to 2013, in three subpopulations (A–C). A modified TOPSIS (weighted and unweighted) analyses is proposed to aggregate preferences from three TEs and to identify the selection method that was closest to the ideal solution agreed upon by the TEs. Criteria weights were provided individually by three TEs. For the group decision making, internal and external aggregation approaches were used with arithmetic and geometric means.The results of the weighted modified TOPSIS analysis showed that the selection methods that used farm registries yielded high estimates of the relative closeness to ideal-solution. The ranking of selection methods based on the modified TOPSIS weighted analysis, conducted at the individual and group decision making levels were similar. Regardless of the aggregation approach used (internal or external) in group decision making, the use of the arithmetic and geometric means yielded similar estimates of relative closeness to ideal-solution.The unweighted modified TOPSIS analysis yielded similar estimates of the relative closeness to the ideal-solution and therefore making the interpretation of the results difficult.The weighted modified TOPSIS analysis contributed to an informed decision on the best selection method to apply in CanNAISS. The weighted modified TOPSIS analysis is a straightforward and suitable technique to address decision making problems where the profile of the ideal and non-ideal solutions is known a priori by the decision makers.

Military and Maritime Evidence of Pandemic Influenza in Canada during the Summer of 1918

Analysis of archival correspondence, the daily logs of troopships transporting soldiers to Europe and the Commonwealth War Graves Commission database for soldier deaths from pneumonia and influenza across Canada indicate that influenza was more common during the summer of 1918 than previously thought. Evidence of pandemic influenza so close to the outbreak of the fall wave calls into question the storyline of a mutated virus causing the emergence of the fall wave of the 1918 influenza pandemic. This highlights the significance of other host, social and environmental circumstances, many related to the First world war, that may have contributed to the severity and timing of pandemic waves in Canada.

The first wave of the 1918 influenza pandemic among soldiers of the Canadian expeditionary force.

This article evaluates the evidence for the presence of the first, mild wave of the 1918 influenza pandemic among soldiers in the Canadian Expeditionary Force (CEF). Death records for soldiers in the CEF who died in Canada in 1917 and 1918 were extracted from the Commonwealth War Graves Commission and record-linked to the Canada War Graves Registers, Circumstances of Casualty database. Monthly mortality rates from pneumonia and influenza (P&I) were compared with mortality rates from all other causes for 1917 and 1918, and by region for 1918. The herald wave of influenza was present among CEF soldiers in 1918. P&I mortality was significantly higher in March and April 1918 than during the same period in 1917. P&I mortality rates varied across the country and were significantly higher among soldiers who died in the Maritime region of Canada. In March, Maritime P&I mortality was significantly higher than its counterpart in the West; in April it was significantly higher than P&I mortality in both the Central and Western regions. The CEF findings suggest that local, geographic heterogeneity characterized the first wave of the 1918 influenza pandemic in Canada and illustrate the ways in which well-established, historical patterns of cross-border social contact with the United States, coupled with the special conditions created by warfare, disproportionately funnelled influenza into particular regions. Identification of the mild first wave among soldiers in the CEF calls for more research on the civilian experience of both waves of influenza in Canada.

Influenza in Canada, 2012-2013 season.

This report summarizes influenza activity in Canada during the 2012-13 influenza season (August 26, 2012-August 24, 2013) from data obtained through the FluWatch surveillance program. FluWatch collected information from six primary indicators of influenza activity that describe the epidemiologic and virologic behaviour of influenza in Canada: sentinel laboratory-based influenza detections; strain characterization and antiviral resistance for circulating influenza viruses; primary care consultation rates of influenza-like illness; regional influenza activity levels; influenza-associated severe outcomes; and pharmacy surveillance. The influenza season peaked nationally between late December 2012 and early January 2013 with influenza A(H3N2) identified as the predominant circulating influenza strain until early March, when influenza B became the predominant circulating strain. The cumulative reported hospitalization rates for all age groups were 25.0 per 100,000. Influenza A most greatly affected adults ≥65 years of age and influenza B most greatly affected children ≤19 years of age. The influenza season was moderately severe. When compared to the previous two seasons, which were considered relatively mild, there was a significant increase in laboratory detections for influenza, as well as hospitalizations associated with influenza in 2012-13.

Adapting a scenario tree model for freedom from disease as surveillance progresses: The Canadian notifiable avian influenza model

Scenario tree models with temporal discounting have been applied in four continents to support claims of freedom from animal disease. Recently, a second (new) model was developed for the same population and disease. This is a natural development because surveillance is a dynamic process that needs to adapt to changing circumstances – the difficulty is the justification for, documentation of, presentation of and the acceptance of the changes.Our objective was to propose a systematic approach to present changes to an existing scenario tree model for freedom from disease. We used the example of how we adapted the deterministic Canadian Notifiable Avian Influenza scenario tree model published in 2011 to a stochastic scenario tree model where the definition of sub-populations and the estimation of probability of introduction of the pathogen were modified.We found that the standardized approach by Vanderstichel et al. (2013) with modifications provided a systematic approach to make and present changes to an existing scenario tree model. We believe that the new 2013 CanNAISS scenario tree model is a better model than the 2011 model because the 2013 model included more surveillance data. In particular, the new data on Notifiable Avian Influenza in Canada from the last 5 years were used to improve input parameters and model structure.

Trends in antiviral therapy of adults hospitalized with influenza in Canada since the end of the 2009 pandemic

BackgroundMultiple observational studies have associated antiviral treatment of patients hospitalized with influenza with improved outcome, including reduced mortality. During the 2009–2010 H1N1 pandemic increased use of antiviral treatment of hospital patients was reported. We have carried out prospective surveillance for influenza in patients in a large network of Canadian hospitals since 2006. We wished to assess trends in antiviral use in the two seasons (2010–2011 and 2011–2012) since the end of the pandemic.FindingsAdults (>16 years) testing positive for influenza at the time of or during admission to participating Canadian hospitals were prospectively reviewed. In 2009–2010 there were 1132 confirmed cases, 1107 in 2010–2011 and 631 in 2011–2012. Information on antiviral therapy was available in >95% in each year. Rising to 89.6% in 2009, the proportion of adult patients treated with antiviral therapy fell to 79.9% and 65.7% in the two subsequent seasons (p < 0.001). Oseltamivir was the antiviral agent used in >98% of cases in each year. The median time from onset of symptoms to initiation of antiviral therapy was three days. The treatment proportion fell across all age groups, co-morbid conditions and disease severity.ConclusionDespite evidence for benefit of antiviral therapy, and clinical practice guidelines recommending treatment of this population, antiviral therapy of Canadian adults hospitalized with influenza has progressively fallen in the two seasons since the end of the 2009–2010 influenza pandemic.

Can informal social distancing interventions minimize demand for antiviral treatment during a severe pandemic?

BackgroundIn the case of a pandemic, individuals may alter their behaviour. A dynamic model incorporating social distancing can provide a mechanism to consider complex scenarios to support decisions regarding antiviral stockpile size while considering uncertainty around behavioural interventions. We have examined the impact of social distancing measures on the demand for limited healthcare resources such as antiviral drugs from a central stockpile during a severe pandemic.MethodsWe used an existing age-structured model for pandemic influenza in Canada and biologically plausible scenarios for severe influenza transmission within the population. We incorporated data from published reports regarding stated intentions to change behaviour during a pandemic as well as the magnitude and duration of time that individuals expected to maintain the behavioural change. We ran simulations for all combinations of parameter values to identify the projected antiviral requirements in each scenario.ResultsWith 12 weeks of distancing, the effect is relatively small for the lowest R0 of 1.6 with a projected stockpile to treat 25.6% being required (IQR = 21.7 – 28.7%) unless the proportion of people involved (81%) and magnitude of the behaviour change is large (69% reduction in contacts). If 24 weeks of distancing occurs, with only a low to moderate reduction in contacts (38% or less), it is not possible to bring treatment requirements below 20% regardless of what proportion of the population engages in distancing measures when transmissibility is high (R0 = 2.0; stockpile size = 31%, IQR = 29.2 – 33.5%).ConclusionsOur results demonstrate that the magnitude and duration of social distancing behaviours during a severe pandemic have an impact on the need for antiviral drugs. However, significant investments over a long period of time (>16 weeks) are required to decrease the need for antiviral treatment to below 10% of the total population for a highly transmissible viral strain (R0 > 1.8). Encouraging individuals to adopt behaviours that decrease their daily contact rate can help to control the spread of the virus until a vaccine becomes available however; relying on these measures to justify stockpiling fewer courses of treatment will not be sufficient in the case of a severe pandemic.

Using a Dynamic Model to Consider Optimal Antiviral Stockpile Size in the Face of Pandemic Influenza Uncertainty.

BackgroundThe Canadian National Antiviral Stockpile (NAS) contains treatment for 17.5% of Canadians. This assumes no concurrent intervention strategies and no wastage due to non-influenza respiratory infections. A dynamic model can provide a mechanism to consider complex scenarios to support decisions regarding the optimal NAS size under uncertainty.MethodsWe developed a dynamic model for pandemic influenza in Canada that is structured by age and risk to calculate the demand for antivirals to treat persons with pandemic influenza under a wide-range of scenarios that incorporated transmission dynamics, disease severity, and intervention strategies. The anticipated per capita number of acute respiratory infections due to viruses other than influenza was estimated for the full pandemic period from surveys based on criteria to identify potential respiratory infections.ResultsOur results demonstrate that up to two thirds of the population could develop respiratory symptoms as a result of infection with a pandemic strain. In the case of perfect antiviral allocation, up to 39.8% of the population could request antiviral treatment. As transmission dynamics, severity and timing of the emergence of a novel influenza strain are unknown, the sensitivity analysis produced considerable variation in potential demand (median: 11%, IQR: 2–21%). If the next pandemic strain emerges in late spring or summer and a vaccine is available before the anticipated fall wave, the median prediction was reduced to 6% and IQR to 0.7–14%. Under the strategy of offering empirical treatment to all patients with influenza like symptoms who present for care, demand could increase to between 65 and 144%.ConclusionsThe demand for antivirals during a pandemic is uncertain. Unless an accurate, timely and cost-effective test is available to identify influenza cases, demand for antivirals from persons infected with other respiratory viruses will be substantial and have a significant impact on the NAS.

Michael G. Tyshenko, SARS Unmasked: Risk Communication of Pandemics and Influenza in Canada, McGill-Queen's/Associated Medical Health Services Studies in the History of Medicine, Health and Society (Montreal: McGill-Queen's University Press, 2010), pp. xii + 451, $34.95, paperback, ISBN: 978-0-7735-36180.

Michael G. Tyshenko, SARS Unmasked: Risk Communication of Pandemics and Influenza in Canada, McGill-Queen's/Associated Medical Health Services Studies in the History of Medicine, Health and Society (Montreal: McGill-Queen's University Press, 2010), pp. xii + 451, $34.95, paperback, ISBN: 978-0-7735-36180. - Volume 56 Issue 1

Hospitalization of pregnant women with pandemic A(H1N1) 2009 influenza in Canada

This article describes the epidemiology of pandemic A(H1N1) 2009 influenza in all Canadian pregnant women admitted to hospital, and compares it with historical inter-pandemic influenza activity. We used weekly hospitalization and death counts of laboratory-confirmed pandemic A(H1N1) influenza cases reported to the Public Health Agency of Canada's (PHAC) 2009-2010 national pandemic influenza surveillance programme. Pregnant women infected and admitted with the pandemic strain were described and compared with: (1) confirmed admissions of all women of reproductive age; (2) all admitted cases reported to PHAC; and (3) to a historical average of inter-pandemic seasonal influenza admissions, and pneumonia and influenza (P&I) admissions for pregnant women. During the pandemic, 263 pregnant women with confirmed infections were admitted; four died in their third trimester. The median age for admitted pregnant cases was 27.5 years, which is consistent with the median age of the 3-year historical inter-pandemic pregnant comparison group. Aboriginal women appeared to be overrepresented but ethnicity was unavailable for 15.2% of all pregnant cases. Overall admission volumes were higher than those for seasonal influenza in the historical comparison group but were lower than those for P&I admissions. Despite increased admission volumes, severe outcomes in pregnant women were proportionally fewer than in all cases admitted for influenza A(H1N1) infection during the pandemic.

Neuraminidase-inhibitor resistance testing for pandemic influenza A (H1N1) 2009 in Ontario, Canada

Background Oseltamivir resistance-associated H275Y mutation in the neuraminidase (NA) gene of pandemic influenza A (H1N1) 2009 was occasionally reported worldwide during the 2009–2010 influenza season. A significant proportion of those were found in immunocompromised or severely ill persons. This phenomenon remains infrequent and clear recommendations for resistance testing are lacking. Objectives Present the suggested clinical selection criteria for antiviral susceptibility testing for influenza in Canada and to describe the Ontarian experience during the 2009–2010 influenza season. Study design Using a defined algorithm, we prospectively screened for OsR with pyrosequencing and phenotypic testing during the 2009–2010 influenza season. Zanamivir resistance was screened using phenotypic and sequencing technique on selected occasions. Clinical data was gathered for the resistant cases. Results A total of 804 clinical H1N1 (2009) positive samples from Ontario were screened for oseltamivir resistance between June 2009 and March 2010. We identified oseltamivir resistance in 5 (0.6%) distinct patients aged 9–62 years. All the resistant strains bore the H275Y mutation. Susceptibility to zanamivir was maintained in all of them. Three patients harboring oseltamivir resistant strain were intensive care unit patients and four were immunocompromised. All were tested for susceptibility because of a repeat positive result for influenza A PCR. Conclusion Oseltamivir resistance was not frequent during the 2009–2010 influenza season but was identified with a systematic and prospective approach to resistance testing. In order to be as sensitive as possible in the detection of those few cases, we report the suggested indications for antiviral susceptibility testing in Canada.

Original Article: A composite epidemic curve for seasonal influenza in Canada with an international comparison

Please cite this paper as: Schanzer et al. (2010) A composite epidemic curve for seasonal influenza in Canada with an international comparison. Influenza and Other Respiratory Viruses 4(5), 295–306.Background Empirical data on laboratory‐confirmed seasonal influenza is limited by very low and possibly non‐systematic case ascertainment as well as geographical variation.Objective To provide a visual representation of an influenza epidemic at the community and regional level using empirical data and to describe the epidemic characteristics.Methods Weekly influenza A confirmations were obtained from the Canadian FluWatch program and American FluView program for the 1997/1998–2006/2007 seasons; 1‐ year data were also available for Europe (FluNet, WHO). For seasons where at least 80% of the influenza A strains were antigenically similar, a composite epidemic curve was created by centring the local epidemics relative to their epidemic midpoint.Results The range in timing of the regional peaks varied from 5 to 13 weeks. Once the epidemic curves were centred relative to their peak, the composite epidemic curves were similar for Canada, the United States and Europe, and the epidemic growth rates were similar for most subgroups (city size; regions; H1N1 versus H3N2 seasons). During the exponential growth period, the number of cases increased by a factor of 1·5–2·0 per week, averaging 1·8. Exponential growth was evident approximately 10 weeks before the peak. Evidence of sustained transmission occurred from mid‐September to early June.Discussion The shape of the composite curve created in this study clearly demonstrates a consistency in the epidemic pattern across geographically disparate locales. Laboratory confirmation will likely play an increasing role in the development of better methods for early detection and summary measures of influenza activity.

Estimating sensitivity of laboratory testing for influenza in Canada through modelling.

BackgroundThe weekly proportion of laboratory tests that are positive for influenza is used in public health surveillance systems to identify periods of influenza activity. We aimed to estimate the sensitivity of influenza testing in Canada based on results of a national respiratory virus surveillance system.Methods and FindingsThe weekly number of influenza-negative tests from 1999 to 2006 was modelled as a function of laboratory-confirmed positive tests for influenza, respiratory syncytial virus (RSV), adenovirus and parainfluenza viruses, seasonality, and trend using Poisson regression. Sensitivity was calculated as the number of influenza positive tests divided by the number of influenza positive tests plus the model-estimated number of false negative tests. The sensitivity of influenza testing was estimated to be 33% (95%CI 32–34%), varying from 30–40% depending on the season and region.ConclusionsThe estimated sensitivity of influenza tests reported to this national laboratory surveillance system is considerably less than reported test characteristics for most laboratory tests. A number of factors may explain this difference, including sample quality and specimen procurement issues as well as test characteristics. Improved diagnosis would permit better estimation of the burden of influenza.

The Horror at Home: The Canadian Military and the “Great” Influenza Pandemic of 19181

L’auteur examine ici les origines et la propagation de l’influenza au Canada pendant la pandémie de grippe espagnole de 1918. Pour cela, il a consulté diverses sources statistiques et archivistiques tirées de dossiers d’hôpitaux militaires. Il avance que les vecteurs de propagation du virus n’auraient pas été les soldats de retour de la Première Guerre mondiale, mais plutôt les soldats américains qui se rendaient outre-mer. L’auteur pose comme postulat que la maladie s’est par la suite propagée au Canada par l’entremise des soldats canadiens que l’on redéployait afin de constituer une force expéditionnaire en Sibérie. L’auteur conclut qu’en choisissant d’élargir l’effort de guerre au détriment de la protection de la santé publique, le Canada a favorisé la dissémination de la pandémie de l’influenza de 1918, qui n’aurait donc pas été une conséquence inévitable de la fin de la guerre.