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"Hien, Nguyen Tran"
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Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: a modelling study
2012
18 500 laboratory-confirmed deaths caused by the 2009 pandemic influenza A H1N1 were reported worldwide for the period April, 2009, to August, 2010. This number is likely to be only a fraction of the true number of the deaths associated with 2009 pandemic influenza A H1N1. We aimed to estimate the global number of deaths during the first 12 months of virus circulation in each country.
We calculated crude respiratory mortality rates associated with the 2009 pandemic influenza A H1N1 strain by age (0–17 years, 18–64 years, and >64 years) using the cumulative (12 months) virus-associated symptomatic attack rates from 12 countries and symptomatic case fatality ratios (sCFR) from five high-income countries. To adjust crude mortality rates for differences between countries in risk of death from influenza, we developed a respiratory mortality multiplier equal to the ratio of the median lower respiratory tract infection mortality rate in each WHO region mortality stratum to the median in countries with very low mortality. We calculated cardiovascular disease mortality rates associated with 2009 pandemic influenza A H1N1 infection with the ratio of excess deaths from cardiovascular and respiratory diseases during the pandemic in five countries and multiplied these values by the crude respiratory disease mortality rate associated with the virus. Respiratory and cardiovascular mortality rates associated with 2009 pandemic influenza A H1N1 were multiplied by age to calculate the number of associated deaths.
We estimate that globally there were 201 200 respiratory deaths (range 105 700–395 600) with an additional 83 300 cardiovascular deaths (46 000–179 900) associated with 2009 pandemic influenza A H1N1. 80% of the respiratory and cardiovascular deaths were in people younger than 65 years and 51% occurred in southeast Asia and Africa.
Our estimate of respiratory and cardiovascular mortality associated with the 2009 pandemic influenza A H1N1 was 15 times higher than reported laboratory-confirmed deaths. Although no estimates of sCFRs were available from Africa and southeast Asia, a disproportionate number of estimated pandemic deaths might have occurred in these regions. Therefore, efforts to prevent influenza need to effectively target these regions in future pandemics.
None.
Journal Article
Social Contact Patterns in Vietnam and Implications for the Control of Infectious Diseases
2011
The spread of infectious diseases from person to person is determined by the frequency and nature of contacts between infected and susceptible members of the population. Although there is a long history of using mathematical models to understand these transmission dynamics, there are still remarkably little empirical data on contact behaviors with which to parameterize these models. Even starker is the almost complete absence of data from developing countries. We sought to address this knowledge gap by conducting a household based social contact diary in rural Vietnam.
A diary based survey of social contact patterns was conducted in a household-structured community cohort in North Vietnam in 2007. We used generalized estimating equations to model the number of contacts while taking into account the household sampling design, and used weighting to balance the household size and age distribution towards the Vietnamese population. We recorded 6675 contacts from 865 participants in 264 different households and found that mixing patterns were assortative by age but were more homogenous than observed in a recent European study. We also observed that physical contacts were more concentrated in the home setting in Vietnam than in Europe but the overall level of physical contact was lower. A model of individual versus household vaccination strategies revealed no difference between strategies in the impact on R(0).
This work is the first to estimate contact patterns relevant to the spread of infections transmitted from person to person by non-sexual routes in a developing country setting. The results show interesting similarities and differences from European data and demonstrate the importance of context specific data.
Journal Article
Clinical Features of Human Influenza A (H5N1) Infection in Vietnam: 2004–2006
2009
Background. The first cases of avian influenza A (H5N1) in humans in Vietnam were detected in early 2004, and Vietnam has reported the second highest number of cases globally. Methods. We obtained retrospective clinical data through review of medical records for laboratory confirmed cases of influenza A (H5N1) infection diagnosed in Vietnam from January 2004 through December 2006. Standard data was abstracted regarding clinical and laboratory features, treatment, and outcome. Results. Data were obtained for 67 (72%) of 93 cases diagnosed in Vietnam over the study period. Patients presented to the hospital after a median duration of illness of 6 days with fever (75%), cough (89%), and dyspnea (81%). Diarrhea and mucosal bleeding at presentation were more common in fatal than in nonfatal cases. Common findings were bilateral pulmonary infiltrates on chest radiograph (72%), lymphopenia (73%), and increased serum transaminase levels (aspartate aminotransferase, 69%; alanine aminotransferase, 61%). Twenty-six patients died (case fatality rate, 39%; 95% confidence interval, 27%–51%) and the most reliable predictor of a fatal outcome was the presence of both neutropenia and raised alanine aminotransferase level at admission, which correctly predicted 91% of deaths and 82% of survivals. The risk of death was higher among persons aged ⩽16 years, compared with older persons (P<.001), and the risk of death was higher among patients who did not receive oseltamivir treatment (P=.048). The benefit of oseltamivir treatment remained after controlling for potential confounding by 1 measure of severity (odds ratio, 0.15; 95% confidence interval, 0.026–0.893; P=.034). Conclusion. In cases of infection with Influenza A (H5N1), the presence of both neutropenia and raised serum transaminase levels predicts a poor outcome. Oseltamivir treatment shows benefit, but treatment with corticosteroids is associated with an increased risk of death.
Journal Article
A Community Cluster of Oseltamivir-Resistant Cases of 2009 H1N1 Influenza
by
Hien, Nguyen Tran
,
Mai, Le Quynh
,
Duong, Tran Nhu
in
Antiviral Agents - therapeutic use
,
Drug Resistance, Viral
,
Exo-a-sialidase
2010
To the Editor:
Oseltamivir-resistant infection with the 2009 pandemic influenza A (H1N1) virus has so far been described only rarely and is conferred by the H275Y substitution in the neuraminidase enzyme.
1
Only 3 of the 32 patients with oseltamivir-resistant infection reported on as of this writing were not receiving oseltamivir when the resistant viruses were detected, and ongoing community transmission has not yet been shown.
1
However, the emergence of oseltamivir-resistant 2009 H1N1 influenza remains a grave concern, since widespread oseltamivir resistance has been observed in seasonal H1N1. This resistance was unrelated to selective drug pressure, and the H275Y substitution did . . .
Journal Article
Thirty years of vaccination in Vietnam: Impact and cost-effectiveness of the national Expanded Programme on Immunization
2015
•Vietnam's EPI has caused sharp decreases in vaccine-preventable disease incidence.•EPI may have saved over 370,000 lives.•EPI represents good value for money.
Countries like Vietnam transitioning to middle-income status increasingly bear the cost of both existing and new vaccines. However, the impact and cost-effectiveness of the Expanded Programme on Immunization (EPI) as a whole has never been assessed on a country level.
Data on vaccine-preventable disease incidence and mortality from Vietnam's national surveillance was analysed to estimate the likely impact that vaccination in 1980–2010 may have had. Adjustment for under-reporting was made by examining trends in reported mumps incidence and in case-fatality risks for each disease. The same data were separately analysed using the Lives Saved Tool (LiST) to give an alternative estimate of impact. The financial cost of EPI in 1996–2010 was also estimated from the perspective of service provider.
National surveillance data suggests that up to 5.7 million diseases cases and 26,000 deaths may have been prevented by EPI. Analysis using LiST suggests that even more deaths (370,000) may have been prevented by measles and pertussis vaccination alone. The cost-effectiveness of EPI is estimated to be around $1000–$27,000 per death prevented.
Two separate approaches to assessing EPI impact in Vietnam give different quantitative results but a common conclusion: that EPI has made a substantial impact on mortality and represents good value for money.
Journal Article
Business Sustainability Assessment Tools—Their Impact on Corporate Sustainability and Reputation: The Case of Listed Companies in Vietnam
2025
To assess the impact of sustainability assessment tools on the sustainability of the business and measure the impact of these tools and the business’s sustainability on the business’s reputation and brand. Scoring the sustainability level according to each criterion of each sustainability assessment tool, run AMOS software to measure the impact of each assessment tool on the sustainability and reputation of the business. This article aims to present and discuss the art of sustainability assessment using integrated assessment tools, including life cycle assessment, data-based assessment of sustainability reports, impact assessment with stakeholders and from stakeholders to make recommendations for further development, consistent with ontology, epistemology, and methodology of aspects of sustainability science. By using integrated tools to assess a business’s sustainability, it is possible to ensure that its activities match the needs and expectations of its stakeholders. This can help build trust and goodwill with the community and contribute to the long-term and sustainable success of the business.
Plain language summary
Business sustainability assessment tools
The article examines how different sustainability assessment tools influence a business’s overall sustainability and evaluates the effect of these tools, along with the business’s sustainability practices, on its reputation and brand image.
The study involves scoring the sustainability level based on specific criteria associated with each assessment tool and utilizing AMOS software to analyze the impact of each tool on the business’s sustainability and reputation.
The article seeks to explore and discuss the practice of sustainability assessment by employing a range of integrated tools, such as life cycle assessment, data-driven analysis of sustainability reports, and impact assessments involving stakeholders. These discussions aim to provide recommendations for future developments in line with the ontological, epistemological, and methodological dimensions of sustainability science. Using a combination of tools to assess a business’s sustainability ensures alignment with stakeholder needs and expectations, thereby fostering trust, building positive community relationships, and supporting the business’s long-term sustainable success. First, it demonstrates that Life Cycle Costing (LCC) has the highest impact on sustainability evaluation, surpassing traditional tools like Life Cycle Assessment (LCA) and Sustainability Reporting. This challenges previous assumptions that environmental metrics alone are sufficient for assessing corporate sustainability. Second, the study reveals that corporate sustainability serves as the strongest intermediary factor influencing business reputation, emphasizing the need for businesses to align sustainability practices with financial and operational strategies.
Journal Article
Lack of Transmission of H5N1 Avian-Human Reassortant Influenza Viruses in a Ferret Model
by
Subbarao, Kanta
,
Matsuoka, Yumiko
,
Donis, Ruben O.
in
Animals
,
Avian flu
,
Biological Sciences
2006
Avian influenza A H5N1 viruses continue to spread globally among birds, resulting in occasional transmission of virus from infected poultry to humans. Probable human-to-human transmission has been documented rarely, but H5N1 viruses have not yet acquired the ability to transmit efficiently among humans, an essential property of a pandemic virus. The pandemics of 1957 and 1968 were caused by avian-human reassortant influenza viruses that had acquired human virus-like receptor binding properties. However, the relative contribution of human internal protein genes or other molecular changes to the efficient transmission of influenza viruses among humans remains poorly understood. Here, we report on a comparative ferret model that parallels the efficient transmission of H3N2 human viruses and the poor transmission of H5N1 avian viruses in humans. In this model, an H3N2 reassortant virus with avian virus internal protein genes exhibited efficient replication but inefficient transmission, whereas H5N1 reassortant viruses with four or six human virus internal protein genes exhibited reduced replication and no transmission. These findings indicate that the human virus H3N2 surface protein genes alone did not confer efficient transmissibility and that acquisition of human virus internal protein genes alone was insufficient for this 1997 H5N1 virus to develop pandemic capabilities, even after serial passages in a mammalian host. These results highlight the complexity of the genetic basis of influenza virus transmissibility and suggest that H5N1 viruses may require further adaptation to acquire this essential pandemic trait.
Journal Article
Determinants of Influenza Transmission in South East Asia: Insights from a Household Cohort Study in Vietnam
2014
To guide control policies, it is important that the determinants of influenza transmission are fully characterized. Such assessment is complex because the risk of influenza infection is multifaceted and depends both on immunity acquired naturally or via vaccination and on the individual level of exposure to influenza in the community or in the household. Here, we analyse a large household cohort study conducted in 2007-2010 in Vietnam using innovative statistical methods to ascertain in an integrative framework the relative contribution of variables that influence the transmission of seasonal (H1N1, H3N2, B) and pandemic H1N1pdm09 influenza. Influenza infection was diagnosed by haemagglutination-inhibition (HI) antibody assay of paired serum samples. We used a Bayesian data augmentation Markov chain Monte Carlo strategy based on digraphs to reconstruct unobserved chains of transmission in households and estimate transmission parameters. The probability of transmission from an infected individual to another household member was 8% (95% CI, 6%, 10%) on average, and varied with pre-season titers, age and household size. Within households of size 3, the probability of transmission from an infected member to a child with low pre-season HI antibody titers was 27% (95% CI 21%-35%). High pre-season HI titers were protective against infection, with a reduction in the hazard of infection of 59% (95% CI, 44%-71%) and 87% (95% CI, 70%-96%) for intermediate (1∶20-1∶40) and high (≥1∶80) HI titers, respectively. Even after correcting for pre-season HI titers, adults had half the infection risk of children. Twenty six percent (95% CI: 21%, 30%) of infections may be attributed to household transmission. Our results highlight the importance of integrated analysis by influenza sub-type, age and pre-season HI titers in order to infer influenza transmission risks in and outside of the household.
Journal Article
Sero-Prevalence Surveillance to Predict Vaccine-Preventable Disease Outbreaks; A Lesson from the 2014 Measles Epidemic in Northern Vietnam
2019
Abstract
Background
During the first half of 2014, a severe outbreak of measles occurred in northern Vietnam, causing 15 033 confirmed cases and 146 deaths.
Methods
To evaluate the population-level seroprevalence of protection against measles in the period before the outbreak, we made use of an existing age-stratified serum bank, collected over the year before the outbreak, between November 2012 and December 2013, from 4 sites across the country (Hanoi, Hue, Dak Lak, and Ho Chi Minh City). Data from the UNICEF’s Multiple Indicator Clustered Surveys (MICS), carried out in Vietnam during the first quarter of 2014, were used to assess the vaccine coverage in 6 ecological regions of Vietnam.
Results
Results revealed a large discrepancy between levels of protection, as estimated from the serology and vaccine coverage estimated by UNICEF’s MICS. Variation in seroprevalence across locations and age groups corresponded with reported numbers of measles cases, most of which were among the 0–2-year-old age group and in the northern part of the country.
Conclusions
Our study presents a strong case in favor of a serosurveillance sentinel network that could be used to proactively tune vaccination policies and other public health interventions.
Journal Article
Transient Introgression of Wolbachia into Aedes aegypti Populations Does Not Elicit an Antibody Response to Wolbachia Surface Protein in Community Members
by
Fraser, Johanna E.
,
Dong Nguyen, Thanh
,
Iturbe-Ormaetxe, Iñaki
in
Aedes aegypti
,
Antibodies
,
Antibody response
2022
Wolbachia is an endosymbiotic bacterium that can restrict the transmission of human pathogenic viruses by Aedes aegypti mosquitoes. Recent field trials have shown that dengue incidence is significantly reduced when Wolbachia is introgressed into the local Ae. aegypti population. Female Ae. aegypti are anautogenous and feed on human blood to produce viable eggs. Herein, we tested whether people who reside on Tri Nguyen Island (TNI), Vietnam developed antibodies to Wolbachia Surface Protein (WSP) following release of Wolbachia-infected Ae. aegypti, as a measure of exposure to Wolbachia. Paired blood samples were collected from 105 participants before and after mosquito releases and anti-WSP titres were measured by ELISA. We determined no change in anti-WSP titres after ~30 weeks of high levels of Wolbachia-Ae. aegypti on TNI. These data suggest that humans are not exposed to the major Wolbachia surface antigen, WSP, following introgression of Wolbachia-infected Ae. aegypti mosquitoes.
Journal Article