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Transmission dynamics and risk factors for pandemic H1N1-related illness: outbreak investigation in a rural community of British Columbia, Canada.

ABSTRACT: To characterize the first-wave epidemiologic features of influenza-like illness (ILI) associated with the novel pandemic A/H1N1 [A(H1N1)pdm09] virus.We used generalized linear mixed models (GLMM) to assess risk factors and non-parametric and/or parametric distributions to estimate attack rates, secondary attack rates (SAR), duration of illness, and serial interval during a laboratory-confirmed community outbreak of A(H1N1)pdm09 clustered around on-reserve residents and households of an elementary school in rural British Columbia, Canada, in late April/early May 2009. ILI details were collected as part of outbreak investigation by community telephone survey in early June 2009.Overall, 92/408 (23%) of participants developed ILI and 36/408 (9%) experienced medically attended ILI (MAILI). The overall SAR in households was 22%: highest among participants 1-4 years of age (yoa) (50%) followed by < 1 yoa (38%), 5-8 yoa (20%), 10-19 yoa (13%), 20-49 yoa (20%), and 50-64 yoa (0%). The median serial interval was estimated at 3·5 days (95% CI: 2·1-5·1). In multivariable GLMM analysis, having a chronic condition (OR: 2·58; 95% CI: 1·1-6·04), younger age [1-8 yoa: OR: 4·63; 95% CI: 2·25-9·52; 9-19 yoa: OR: 1·95; 95% CI: 0·97-3·9 (referent: ? 20 yoa)] and receipt of 2008-2009 influenza vaccine (OR: 2·68; 95% CI: 1·37-5·25) were associated with increased risk of ILI. Median duration of illness was 9 days, longer among those with chronic conditions (21 days). Median time to seeking care after developing illness was 4·5 days. On-reserve participants had higher chronic conditions, household density, ILI, MAILI, and SAR.During a community outbreak of A(H1N1)pdm09-related illness, we identified substantial clinical ILI attack rates exceeding 20% with secondary household attack rates as high as 50% in young children. The serial interval was short suggesting a narrow period to prevent transmission.

SUBMITTER: Janjua NZ

PROVIDER: S-EPMC4986582 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Transmission dynamics and risk factors for pandemic H1N1-related illness: outbreak investigation in a rural community of British Columbia, Canada.

Janjua Naveed Z NZ Skowronski Danuta M DM Hottes Travis S TS Osei William W Adams Evan E Petric Martin M Lem Marcus M Tang Patrick P De Serres Gaston G Patrick David M DM Bowering David D

Influenza and other respiratory viruses 20120302 3

<h4>Objective</h4>To characterize the first-wave epidemiologic features of influenza-like illness (ILI) associated with the novel pandemic A/H1N1 [A(H1N1)pdm09] virus.<h4>Methods</h4>We used generalized linear mixed models (GLMM) to assess risk factors and non-parametric and/or parametric distributions to estimate attack rates, secondary attack rates (SAR), duration of illness, and serial interval during a laboratory-confirmed community outbreak of A(H1N1)pdm09 clustered around on-reserve reside ...[more]

PMID: 22385647

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Project description:BackgroundClose-contact rates are thought to be a driving force behind the transmission of many infectious respiratory diseases. Yet, contact rates and their relation to transmission and the impact of control measures, are seldom quantified. We quantify the response of contact rates, reported cases and transmission of COVID-19, to public health contact-restriction orders, and examine the associations among these three variables in the province of British Columbia, Canada.MethodsWe derived time series data for contact rates, daily cases and transmission of COVID-19 from a social contacts survey, reported case counts and by fitting a transmission model to reported cases, respectively. We used segmented regression to investigate impacts of public health orders; Pearson correlation to determine associations between contact rates and transmission; and vector autoregressive modeling to quantify lagged associations between contacts rates, daily cases, and transmission.ResultsDeclines in contact rates and transmission occurred concurrently with the announcement of public health orders, whereas declines in cases showed a reporting delay of about 2 weeks. Contact rates were a significant driver of COVID-19 and explained roughly 19 and 20% of the variation in new cases and transmission, respectively. Interestingly, increases in COVID-19 transmission and cases were followed by reduced contact rates: overall, daily cases explained about 10% of the variation in subsequent contact rates.ConclusionWe showed that close-contact rates were a significant time-series driver of transmission and ultimately of reported cases of COVID-19 in British Columbia, Canada and that they varied in response to public health orders. Our results also suggest possible behavioral feedback, by which increased reported cases lead to reduced subsequent contact rates. Our findings help to explain and validate the commonly assumed, but rarely measured, response of close contact rates to public health guidelines and their impact on the dynamics of infectious diseases.

Project description:Background:Pregnant girls/young women and new mothers living in situations of social and economic disadvantage are at increased risk for poor health. Rural living may compound marginalization and create additional challenges for young mothers. Public health nurses (PHNs) delivering the Nurse-Family Partnership (NFP) to mothers living in rural communities may help to improve maternal and child health outcomes. The purpose of this analysis, grounded in data collected as part of a broader process evaluation, was to explore and understand the influence of rural geography on the delivery of NFP in British Columbia, Canada. Methods:For the analysis of this qualitative data, principles of inductive reasoning based on the methodology of interpretive description were applied. A total of 10 PHNs and 11 supervisors providing the NFP program in rural communities were interviewed. Results:The results of this analysis reflect the factors and challenges of providing the NFP program in rural communities. PHNs noted the importance of NFP in the lives of their rural clients, especially in the face of extreme financial and social disparity. Remaining flexible in their approach to rural nursing and protecting time to complete NFP work supported nurses practicing in rural environments. Rural PHNs were often the sole NFP nurse in their office and struggled to remain connected to their supervisors and other NFP colleagues. Challenges were compounded by the realities of rural geography, such as poor weather, reduced accessibility, and long travel distances; however, these were considered normal occurrences of rural practice by nurses. Conclusions:PHNs and NFP supervisors are well-positioned to identify the modifications that are required to support the delivery of NFP in rural geography. NFP nurses need to articulate what classifies as rural in order to effectively determine how to best provide services to these populations. Environmental conditions must be considered when offering NFP in rural communities, particularly if they impact the time required to deliver the program and additional services offered to young mothers. Regular NFP meetings and education opportunities address common problems associated with rural nursing but could be enhanced by better use of technology.

Dataset Information

Transmission dynamics and risk factors for pandemic H1N1-related illness: outbreak investigation in a rural community of British Columbia, Canada.

Publications

Transmission dynamics and risk factors for pandemic H1N1-related illness: outbreak investigation in a rural community of British Columbia, Canada.

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