Understanding transmission dynamics of the pandemic influenza A (H1N1) virus in various exposure settings and determining whether transmissibility differed from seasonal influenza viruses was a priority for decision making on mitigation strategies at the beginning of the pandemic. The objective of this study was to estimate household secondary attack rates for pandemic influenza in a susceptible population where control measures had yet to be implemented.
All Ontario local health units were invited to participate; seven health units volunteered. For all laboratory-confirmed cases reported between April 24 and June 18, 2009, participating health units performed contact tracing to detect secondary cases among household contacts. In total, 87 cases and 266 household contacts were included in this study. Secondary cases were defined as any household member with new onset of acute respiratory illness (fever or two or more respiratory symptoms) or influenza-like illness (fever plus one additional respiratory symptom). Attack rates were estimated using both case definitions.
Secondary attack rates were estimated at 10.3% (95% CI 6.8-14.7) for secondary cases with influenza-like illness and 20.2% (95% CI 15.4-25.6) for secondary cases with acute respiratory illness. For both case definitions, attack rates were significantly higher in children under 16 years than adults (25.4% and 42.4% compared to 7.6% and 17.2%). The median time between symptom onset in the primary case and the secondary case was estimated at 3.0 days.
Secondary attack rates for pandemic influenza A (H1N1) were comparable to seasonal influenza estimates suggesting similarities in transmission. High secondary attack rates in children provide additional support for increased susceptibility to infection.
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Cites: Clin Infect Dis. 2010 Nov 1;51(9):1033-4120887206
Building on previous research noting variations in the operation and perceived utility of syndromic surveillance systems in Ontario, the timeliness of these different syndromic systems for detecting the onset of both 2009 H1N1 pandemic (A(H1N1)pdm09) waves relative to laboratory testing data was assessed using a standardized analytic algorithm.
Syndromic data, specifically local emergency department (ED) visit and school absenteeism data, as well as provincial Telehealth (telephone helpline) and antiviral prescription data, were analyzed retrospectively for the period April 1, 2009 to January 31, 2010. The C2-MEDIUM aberration detection method from the US Centers for Disease Control and Prevention's EARS software was used to detect increases above expected in syndromic data, and compared to laboratory alerts, defined as notice of confirmed A(H1N1)pdm09 cases over two consecutive days, to assess relative timeliness.
In Wave 1, provincial-level alerts were detected for antiviral prescriptions and Telehealth respiratory calls before the laboratory alert. In Wave?2, Telehealth respiratory calls similarly alerted in advance of the laboratory, while local alerts from ED visit, antiviral prescription and school absenteeism data varied in timing relative to the laboratory alerts. Alerts from syndromic data were also observed to coincide with external factors such as media releases.
Alerts from syndromic surveillance systems may be influenced by external factors and variation in system operations. Further understanding of both the impact of external factors on surveillance data and standardizing protocols for defining alerts is needed before the use of syndromic surveillance systems can be optimized.
Reporting health data for large urban areas presents numerous challenges. In the case of Toronto, Ontario, amalgamation in 1998 merged six census subdivisions into one mega-city, resulting in the disappearance of standard reporting units. A population-based approach was used to define new health planning areas. Census tracts were used as building blocks and combined according to residential income homogeneity, respecting natural and man-made boundaries, forward sortation areas and the City of Toronto's community neighbourhoods whenever possible. Correlations and maps were used to establish area boundaries. The city was divided into 5 major planning areas which were further subdivided creating 15 minor areas. Both major and minor areas showed significant differences in population characteristics, health status and health service utilization. This commentary demonstrates the feasibility and describes the outcomes of one method for establishing planning and reporting areas in large urban centres. Next steps include the further generation of health data for these areas, comparisons with other Canadian urban areas, and application of these methods to recently announced Ontario Local Health Integration Networks. These areas can be used for planning and evaluating health service delivery, comparison with other Canadian urban areas and ongoing monitoring of and advocacy for equity in health.
Since 2007, all Canadian medical schools have had at least one established student-led public health interest group (PHIG). The Association of Faculties of Medicine of Canada (AFMC), the Public Health Task Group, and the Public Health Agency of Canada (PHAC) have supported these PHIGs. The authors describe the activities and structure of PHIGs in Canada from 2007 to 2011, plus the extent to which PHIGs met the objectives set out for them by the AFMC Public Health Task Group.
Using a standardized template, the authors analyzed funding applications and reports that PHIG executives submitted to the AFMC from 2007 through 2011. The authors created activity categories and collected simple counts of activities within categories. They then used these data to assess how successfully PHIGs have been able to meet their objectives.
Fifty-two funding applications, 50 interim reports, and 48 final reports were available for analysis. All 17 Canadian medical schools had at least one established PHIG between 2007 and 2011, and 9 schools (53%) applied for PHIG funding in all four years. Academic activities such as lectures, seminars, and workshops were the most common activities conducted by PHIGs, followed by career exploration and networking.
This study found that the AFMC, with funding support from PHAC, was instrumental in initiating PHIGs in 82% (n = 14) of Canadian medical schools. With consistent funding, national networking opportunities, and a common operating structure, PHIGs have been able to accomplish AFMC's objectives for increasing public health awareness amongst medical students.
In the 2003 outbreak in Toronto (in Ontario, Canada) of severe acute respiratory syndrome (SARS), about 20% of cases resulted from household transmission. The purpose of our study was to determine characteristics associated with the transmission of SARS within households.
A retrospective cohort of SARS-affected households was studied to determine risk factors for household transmission. Questionnaires addressed characteristics of the index case, the household and behaviours among household members. Potential risk factors for secondary transmission of infection were assessed in regression models appropriate to the outcome (secondary cases) and nonindependence of household members.
The 74 households that participated included 18 secondary cases and 158 uninfected household members in addition to the 74 index cases. The household secondary attack rate was 10.2% (95% confidence interval [CI] 6.7%-23.5%). There was a linear association between the time the index patient spent at home after symptom onset and the secondary attack rate. Infected health care workers who were index cases had lower rates of household transmission.
SARS transmission in households is complex and increases with the length of time an ill person spends at home. Risk of transmission was lower when the index case was a health care worker. Rapid case identification is the public health measure most useful in minimizing exposure in the home.
Public health authorities have prioritized the identification of competencies, yet little empirical data exist to support decisions on competency selection among particular disciplines. We sought perspectives on important competencies among epidemiologists familiar with or practicing in public health settings (local to national).
Using a sequential, qualitative-quantitative mixed method design, we conducted key informant interviews with 12 public health practitioners familiar with front-line epidemiologists' practice, followed by a web-based survey of members of a provincial association of public health epidemiologists (90 respondents of 155 eligible) and a consensus workshop. Competency statements were drawn from existing core competency lists and those identified by key informants, and ranked by extent of agreement in importance for entry-level practitioners.
Competencies in quantitative methods and analysis, critical appraisal of scientific evidence and knowledge transfer of scientific data to other members of the public health team were all regarded as very important for public health epidemiologists. Epidemiologist competencies focused on the provision, interpretation and 'translation' of evidence to inform decision-making by other public health professionals. Considerable tension existed around some potential competency items, particularly in the areas of more advanced database and data-analytic skills.
Empirical data can inform discussions of discipline-specific competencies as one input to decisions about competencies appropriate for epidemiologists in the public health workforce.
Abraham Flexner's 1910 report is credited with promoting critical reforms in medical education. Because Flexner advocated scientific rigor and standardization in medical education, his report has been perceived to place little emphasis on the importance of public health in clinical education and training. However, a review of the report reveals that Flexner presciently identified at least three public-health-oriented principles that contributed to his arguments for medical education reform: (1) The training, quality, and quantity of physicians should meet the health needs of the public, (2) physicians have societal obligations to prevent disease and promote health, and medical training should include the breadth of knowledge necessary to meet these obligations, and (3) collaborations between the academic medicine and public health communities result in benefits to both parties. In this article, commemorating the Flexner Centenary, the authors review the progress of U.S. and Canadian medical schools in addressing these principles in the context of contemporary societal health needs, provide an update on recent efforts to address what has long been perceived as a deficit in medical education (inadequate grounding of medical students in public health), and provide new recommendations on how to create important linkages between medical education and public health. Contemporary health challenges that require a public health approach in addition to one-on-one clinical skills include containing epidemics of preventable chronic diseases, reforming the health care system to provide equitable high-quality care to populations, and responding to potential disasters in an increasingly interconnected world. The quantitative skills and contextual knowledge that will prepare physicians to address these and other population health problems constitute the basics of public health and should be included throughout the continuum of medical education.
Despite the growing popularity of syndromic surveillance, little is known about if or how these systems are accepted, utilized and valued by end users. This study seeks to describe the use of syndromic surveillance systems in Ontario and users' perceptions of the value of these systems within the context of other surveillance systems.
Ontario's 36 public health units, the provincial ministry of health and federal public health agency completed a web survey to identify traditional and syndromic surveillance systems used routinely and during the pandemic and to describe system attributes and utility in monitoring pandemic activity and informing decision-making.
Syndromic surveillance systems are used by 20/38 (53%) organizations. For routine surveillance, laboratory, integrated Public Health Information System and school absenteeism data are the most frequently used sources. Laboratory data received the highest ratings for reliability, timeliness and accuracy ('very acceptable' by 92, 51 and 89%). Hospital/clinic screening data were rated as the most reliable and timely syndromic data source (50 and 43%) and ED visit data the most accurate (48%). During the pandemic, laboratory data were considered the most useful for monitoring the epidemiology and informing decision-making while ED screening and visit data were considered the most useful syndromic sources.
End user perceptions are valuable for identifying opportunities for improvement and guiding further investments in public health surveillance.
We designed a seroprevalence study using multiple testing assays and population sources to estimate the community seroprevalence of pH1N1/09 and risk factors for infection before the outbreak was recognized and throughout the pandemic to the end of 2009/10 influenza season.
Residual serum specimens from five time points (between 01/2009 and 05/2010) and samples from two time points from a prospectively recruited cohort were included. The distribution of risk factors was explored in multivariate adjusted analyses using logistic regression among the cohort. Antibody levels were measured by hemagglutination inhibition (HAI) and microneutralization (MN) assays.
Residual sera from 3375 patients and 1024 prospectively recruited cohort participants were analyzed. Pre-pandemic seroprevalence ranged from 2%-12% across age groups. Overall seropositivity ranged from 10%-19% post-first wave and 32%-41% by the end of the 2009/10 influenza season. Seroprevalence and risk factors differed between MN and HAI assays, particularly in older age groups and between waves. Following the H1N1 vaccination program, higher GMT were noted among vaccinated individuals. Overall, 20-30% of the population was estimated to be infected.
Combining population sources of sera across five time points with prospectively collected epidemiological information yielded a complete description of the evolution of pH1N1 infection.
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In Canada, recent events and global influences have led to an emphasis on enhancing the public health system and improving the training of physicians in public and population health. Responding to the World Health Organization's initiative, Towards Unity for Health, the Association of Faculties of Medicine in Canada launched its Social Accountability initiative in 2001, which included the creation of the Public Health Task Group. With representation from the Public Health Agency of Canada, Canadian faculties of medicine, medical students, the Medical Council of Canada, and the community, the task group undertook four main steps: reaching agreement on common overall objectives for teaching public health, obtaining baseline information on the curricula of programs that were being provided across Canada, obtaining an inventory of resources available at each university, and creating a support system for fostering the development of public health teaching in undergraduate medicine programs. To date, the seventeen medical schools have nearly reached full consensus on the overall educational objectives. An initial scan of existing educational resources revealed no consistent use of any one text. Subsequent work has begun to create an inventory of sharable resources. A network of public health educators has been created and is seen as a promising start to addressing these other concerns. Other barriers remain to be addressed; these include lack of faculty (critical mass), inadequate support for local champions, inadequate methods of student assessment, and poor image as an attractive specialty/few role models.