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2009-2010 Influenza A(H1N1)-related critical illness among Aboriginal and non-Aboriginal Canadians.

ABSTRACT: Preliminary studies suggested that Aboriginal Canadians had disproportionately higher rates of infection, hospitalization, and critical illness due to pandemic Influenza A(H1N1)pdm09.We used a prospective cohort study of critically ill patients with laboratory confirmed or probable H1N1 infection in Canada between April 16 2009 and April 12 2010. Baseline characteristics, medical interventions, clinical course and outcomes were compared between Aboriginal and non-Aboriginal patients. The primary outcome was hospital mortality.Of 647 critically ill adult patients with known ethnicity, 81 (12.5%) were Aboriginal, 566 (87.5%) were non-Aboriginal. Aboriginal patients were younger (mean [SD] age 40.7[13.7] v. 49.0[14.9] years, p < 0.001) and more frequently female (64.2% v. 51.1%, p = 0.027). Rates of any co-morbid illnesses (Aboriginal v. non-Aboriginal, 92.6% v. 91.0%, p = 0.63), time from symptom onset to hospital admission (median [interquartile range] 4 [2-7] v. 4 [2-7] days, p = 0.84), time to ICU admission (5 [3-8] v.5 [3-8] days, p = 0.91), and severity of illness (mean APACHE II score (19.9 [9.6] v. 21.1 [9.9], p = 0.33) were similar. A similar proportion of Aboriginal patients received antiviral medication before ICU admission than non-Aboriginal patients (91.4% v. 93.8%, p = 0.40). Among Aboriginal versus non-Aboriginal patients, the need for mechanical ventilation (93.8% v. 88.6%, p = 0.15), ventilator-free days (14 [3-23] v. 17 [0-24], p = 0.62), durations of stay in ICU (13[7-19.5] v. 11 [5-8] days, p = 0.05), hospital (19 [12.5-33.5] v. 18 [11-35] days, p = 0.63), and hospital mortality were similar (19.8% v. 22.6%, p = 0.56). In multiple logistic regression analyses, higher APACHE II score (1.06; 1.04-1.09, p<0.001) was independently associated with an increased risk of death; antiviral treatment with a lower risk of death (0.34; 0.15 - 0.78, p = 0.01). Ethnicity was not associated with mortality.During the 2009-2010 Influenza A (H1N1) pandemic, Aboriginal and non-Aboriginal Canadians with H1N1-related critical illness had a similar risk of death, after adjusting for potential confounding factors.

SUBMITTER: Jung JJ

PROVIDER: S-EPMC5648104 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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2009-2010 Influenza A(H1N1)-related critical illness among Aboriginal and non-Aboriginal Canadians.

Jung James J JJ Pinto Ruxandra R Zarychanski Ryan R Cook Deborah J DJ Jouvet Philippe P Marshall John C JC Kumar Anand A Long Jennifer J Rodin Rachel R Fowler Robert A RA

PloS one 20171019 10

<h4>Background</h4>Preliminary studies suggested that Aboriginal Canadians had disproportionately higher rates of infection, hospitalization, and critical illness due to pandemic Influenza A(H1N1)pdm09.<h4>Methods</h4>We used a prospective cohort study of critically ill patients with laboratory confirmed or probable H1N1 infection in Canada between April 16 2009 and April 12 2010. Baseline characteristics, medical interventions, clinical course and outcomes were compared between Aboriginal and n ...[more]

PMID: 29049285

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Project description:Because many Aboriginal Canadians had severe cases of pandemic (H1N1) 2009 influenza, they were given priority access to vaccine. However, it was not known if the single recommended dose would adequately protect people at high risk, prompting our study to assess responses to the vaccine among Aboriginal Canadians.We enrolled First Nations and Métis adults aged 20-59 years in our prospective cohort study. Participants were given one 0.5-mL dose of ASO3-adjuvanted pandemic (H1N1) 2009 vaccine (Arepanrix, GlaxoSmithKline Canada). Blood samples were taken at baseline and 21-28 days after vaccination. Paired sera were tested for hemagglutination-inhibiting antibodies at a reference laboratory. To assess vaccine safety, we monitored the injection site symptoms of each participant for seven days. We also monitored patients for general symptoms within 7 days of vaccination and any use of the health care system for 21-28 days after vaccination.We enrolled 138 participants in the study (95 First Nations, 43 Métis), 137 of whom provided all safety data and 136 of whom provided both blood samples. First Nations and Métis participants had similar characteristics, including high rates of chronic health conditions (74.4%-76.8%). Pre-existing antibody to the virus was detected in 34.3% of the participants, all of whom boosted strongly with vaccination (seroprotection rate [titre ? 40] 100%, geometric mean titre 531-667). Participants with no pre-existing antibody also responded well. Fifty-eight of 59 (98.3%) First Nations participants showed seroprotection and a geometric mean titre of 353.6; all 30 Métis participants with no pre-existing antibody showed seroprotection and a geometric mean titre of 376.2. Pain at the injection site and general symptoms frequently occurred but were short-lived and generally not severe, although three participants (2.2%) sought medical attention for general symptoms.First Nations and Métis adults responded robustly to ASO3-adjuvanted pandemic (H1N1) 2009 vaccine. Virtually all participants showed protective titres, including those with chronic health conditions.

Project description:BACKGROUND:Over the last decade, capacity for influenza surveillance and research in West Africa has strengthened. Data from these surveillance systems showed influenza A(H1N1)pdm09 circulated in West Africa later than in other regions of the continent. METHODS:We contacted 11 West African countries to collect information about their influenza surveillance systems (number of sites, type of surveillance, sampling strategy, populations sampled, case definitions used, number of specimens collected and number of specimens positive for influenza viruses) for the time period January 2010 through December 2012. RESULTS:Of the 11 countries contacted, 8 responded: Burkina Faso, Cote d'Ivoire, Mali, Mauritania, Niger, Nigeria, Sierra Leone and Togo. Countries used standard World Health Organization (WHO) case definitions for influenza-like illness (ILI) and severe acute respiratory illness (SARI) or slight variations thereof. There were 70 surveillance sites: 26 SARI and 44 ILI. Seven countries conducted SARI surveillance and collected 3114 specimens of which 209 (7%) were positive for influenza viruses. Among influenza-positive SARI patients, 132 (63%) were influenza A [68 influenza A(H1N1)pdm09, 64 influenza A(H3N2)] and 77 (37%) were influenza B. All eight countries conducted ILI surveillance and collected 20,375 specimens, of which 2278 (11%) were positive for influenza viruses. Among influenza-positive ILI patients, 1431 (63%) were influenza A [820 influenza A(H1N1)pdm09, 611 influenza A(H3N2)] and 847 (37%) were influenza B. A majority of SARI and ILI case-patients who tested positive for influenza (72% SARI and 59% ILI) were children aged 0-4 years, as were a majority of those enrolled in surveillance. The seasonality of influenza and the predominant influenza type or subtype varied by country and year. CONCLUSIONS:Influenza A(H1N1)pdm09 continued to circulate in West Africa along with influenza A(H3N2) and influenza B during 2010-2012. Although ILI surveillance systems produced a robust number of samples during the study period, more could be done to strengthen surveillance among hospitalized SARI case-patients. Surveillance systems captured young children but lacked data on adults and the elderly. More data on risk groups for severe influenza in West Africa are needed to help shape influenza prevention and clinical management policies and guidelines.

Project description:BackgroundInternet-based surveillance systems to monitor influenza-like illness (ILI) have advantages over traditional (physician-based) reporting systems, as they can potentially monitor a wider range of cases (i.e. including those that do not seek care). However, the requirement for participants to have internet access and to actively participate calls into question the representativeness of the data. Such systems have been in place in a number of European countries over the last few years, and in July 2009 this was extended to the UK. Here we present results of this survey with the aim of assessing the reliability of the data, and to evaluate methods to correct for possible biases.MethodsInternet-based monitoring of ILI was launched near the peak of the first wave of the UK H1N1v influenza pandemic. We compared the recorded ILI incidence with physician-recorded incidence and an estimate of the true number of cases over the course of the epidemic. We also compared overall attack rates. The effect of using different ILI definitions and alternative denominator assumptions on incidence estimates was explored.ResultsThe crude incidence measured by the internet-based system appears to be influenced by individuals who participated only once in the survey and who appeared more likely to be ill. This distorted the overall incidence trend. Concentrating on individuals who reported more than once results in a time series of ILI incidence that matches the trend of case estimates reasonably closely, with a correlation of 0.713 (P-value: 0.0001, 95% CI: 0.435, 0.867). Indeed, the internet-based system appears to give a better estimate of the relative height of the two waves of the UK pandemic than the physician-recorded incidence. The overall attack rate is, however, higher than other estimates, at about 16% when compared with a model-based estimate of 6%.ConclusionInternet-based monitoring of ILI can capture the trends in case numbers if appropriate weighting is used to correct for differential response. The overall level of incidence is, however, difficult to measure. Internet-based systems may be a useful adjunct to existing ILI surveillance systems as they capture cases that do not necessarily contact health care. However, further research is required before they can be used to accurately assess the absolute level of incidence in the community.

Dataset Information

2009-2010 Influenza A(H1N1)-related critical illness among Aboriginal and non-Aboriginal Canadians.

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2009-2010 Influenza A(H1N1)-related critical illness among Aboriginal and non-Aboriginal Canadians.

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