Publications by authors named "Le Khanh Hang Nguyen"

7 Publications

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Severe Acute Respiratory Syndrome Coronavirus 2 Shedding by Travelers, Vietnam, 2020.

Emerg Infect Dis 2020 07 21;26(7):1624-1626. Epub 2020 Jun 21.

We analyzed 2 clusters of 12 patients in Vietnam with severe acute respiratory syndrome coronavirus 2 infection during January-February 2020. Analysis indicated virus transmission from a traveler from China. One asymptomatic patient demonstrated virus shedding, indicating potential virus transmission in the absence of clinical signs and symptoms.
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http://dx.doi.org/10.3201/eid2607.200591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7323563PMC
July 2020

Swine influenza viruses in Northern Vietnam in 2013-2014.

Emerg Microbes Infect 2018 Jul 2;7(1):123. Epub 2018 Jul 2.

WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong-Hong Kong Special Administrative Region, Hong Kong, China.

Swine are an important intermediate host for emergence of pandemic influenza. Vietnam is the largest swine producer in South East Asia. Systematic virological and serological surveillance of swine influenza viruses was carried out in Northern Vietnam from May 2013 to June 2014 with monthly sampling of pigs in local and large collective slaughterhouses and in a live pig market. Influenza A seroprevalence in the local slaughterhouses and in the large collective slaughterhouse was 48.7% and 29.1%, respectively. Seventy-seven influenza A viruses were isolated, all from the large collective slaughterhouse. Genetic analysis revealed six virus genotypes including H1N1 2009 pandemic (H1N1pdm09) viruses, H1N2 with H1 of human origin, H3N2 and H1N1pdm09 reassortants, and triple-reassortant H3N2 viruses. Phylogenetic analysis of swine and human H1N1pdm09 viruses showed evidence of repeated spill-over from humans to swine rather than the establishment of H1N1pdm09 as long-term distinct lineage in swine. Surveillance at the large collective slaughterhouse proved to be the most efficient, cost-effective, and sustainable method of surveillance for swine influenza viruses in Vietnam.
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http://dx.doi.org/10.1038/s41426-018-0109-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6028489PMC
July 2018

Neuraminidase inhibitor susceptibility and evolutionary analysis of human influenza B isolates from three Asian countries during 2012-2015.

Infect Genet Evol 2018 08 14;62:27-33. Epub 2018 Apr 14.

Department of Pathology, Immunology, and Microbiology, Faculty of Medicine American University of Beirut, Lebanon; Center for Infectious Disease Research, Faculty of Medicine American University of Beirut, Beirut, Lebanon. Electronic address:

Influenza B viruses of both the Yamagata and the Victoria lineages are implicated in a large proportion of the morbidity and mortality associated with influenza outbreaks. In this study, we characterized the full genomes of 53 influenza B viruses isolated during 2012-2015 in three Asian countries: Japan, Myanmar, and Vietnam. Analysis of the hemagglutinin (HA) genes revealed co-circulation of both the Yamagata and Victoria lineages within the same season in these countries. Our analysis revealed, that a large proportion of viruses circulating during 2013-2014 in Japan and Vietnam were mismatched to the vaccine supporting the rationale for using quadrivalent vaccines. Molecular analysis of the neuraminidase (NA) genes did not reveal any of the previously reported substitutions associated with reduced susceptibility to neuraminidase inhibitors (NAIs). However, one isolate from Nagasaki displayed reduced inhibition by NAIs, associated with an NA-M426I substitution (N2-numbering). Phylogenetic analysis of the eight genome segments identified a 6 + 2 reassortant strain belonging to the Victoria lineage that circulated in Japan during the 2013-2014 season. This strain appears to have evolved from a descendent of a B/Brisbane/60/2008-like strain in an intra-lineage reassortment event involving the nucleoprotein (NP) and nonstructural (NS) genes. Therefore, influenza B strains circulating worldwide continue to evolve via complex reassortment events, which contribute to their survival and the emergence of new strains. These findings highlight the need for ongoing genome-wide studies of circulating viruses and assessing the implications of these evolutionary events on the vaccines.
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http://dx.doi.org/10.1016/j.meegid.2018.04.016DOI Listing
August 2018

Circulation of influenza B lineages in northern Viet Nam, 2007-2014.

Western Pac Surveill Response J 2015 Oct-Dec;6(4):17-23. Epub 2015 Nov 11.

National Institute of Hygiene and Epidemiology, Ha Noi, Viet Nam .

Introduction: Influenza B viruses circulate throughout Viet Nam, and their activities vary by region. There have been two antigenically distinct lineages of influenza B viruses co-circulating in the past 20 years; however, only one lineage is selected as a component of contemporary trivalent seasonal influenza vaccines. To improve the understanding of circulating influenza B lineages and influenza vaccine mismatches, we report the virus lineages circulating in northern Viet Nam over an eight-year period (2007-2014).

Methods: Lineages of 331 influenza B viruses were characterized by haemagglutination inhibition assay against standard reference ferret (Yamagata) and sheep (Victoria) antisera. Sequence analysis of the haemagglutinin gene was performed in 64 selected influenza B isolates.

Results: The proportion of influenza B lineages changed by year. The Yamagata lineage predominated in 2007, 2008 and 2012; the Victoria lineage predominated in 2009-2014 except 2012. The two lineages showed continuous evolution over time. The Northern Hemisphere's influenza vaccine components were mismatched with the predominant circulating viruses in 2007, 2009 and 2014.

Discussion: The seasonality of influenza B activity is more variable in tropical and subtropical regions than in temperate zones. Our data showed a common co-circulation of both influenza B lineages in northern Viet Nam, and it was difficult to predict which one was the predominant lineage. Quadrivalent influenza vaccines containing both lineages may improve the effectiveness of influenza vaccine programmes in the future.
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http://dx.doi.org/10.5365/WPSAR.2015.6.1.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4712529PMC
October 2016

Hemagglutination inhibiting antibodies and protection against seasonal and pandemic influenza infection.

J Infect 2015 Feb 16;70(2):187-96. Epub 2014 Sep 16.

Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.

Objectives: Hemagglutination inhibiting (HI) antibodies correlate with influenza vaccine protection but their association with protection induced by natural infection has received less attention and was studied here.

Methods: 940 people from 270 unvaccinated households participated in active ILI surveillance spanning 3 influenza seasons. At least 494 provided paired blood samples spanning each season. Influenza infection was confirmed by RT-PCR on nose/throat swabs or serum HI assay conversion.

Results: Pre-season homologous HI titer was associated with a significantly reduced risk of infection for H3N2 (OR 0.61, 95%CI 0.44-0.84) and B (0.65, 95%CI 0.54-0.80) strains, but not H1N1 strains, whether re-circulated (OR 0.90, 95%CI 0.71-1.15), new seasonal (OR 0.86, 95%CI 0.54-1.36) or pandemic H1N1-2009 (OR 0.77, 95%CI 0.40-1.49). The risk of seasonal and pandemic H1N1 decreased with increasing age (both p < 0.0001), and the risk of pandemic H1N1 decreased with prior seasonal H1N1 (OR 0.23, 95%CI 0.08-0.62) without inducing measurable A/California/04/2009-like titers.

Conclusions: While H1N1 immunity was apparent with increasing age and prior infection, the effect of pre-season HI titer was at best small, and weak for H1N1 compared to H3N2 and B. Antibodies targeting non-HI epitopes may have been more important mediators of infection-neutralizing immunity for H1N1 compared to other subtypes in this setting.
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http://dx.doi.org/10.1016/j.jinf.2014.09.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4309889PMC
February 2015

Oseltamivir resistance among influenza viruses: surveillance in northern Viet Nam, 2009-2012.

Western Pac Surveill Response J 2013 Apr-Jun;4(2):25-9. Epub 2013 Jun 26.

National Influenza Center, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.

Introduction: Antiviral resistance has been reported in seasonal influenza A viruses and avian influenza A(H5N1) viruses in Viet Nam, raising concerns about the efficacy of treatment.

Methods: We analysed specimens from two sources during the period 2009-2012: influenza-positive samples from influenza-like illness patients at sentinel clinics in northern Viet Nam and isolates from patients with confirmed A(H5N1) infections. Pyrosequencing was used to detect mutations: H275Y [for A(H1N1) and A(H5N1)], E119V [for A(H3N2)] and I117V [for A(H5N1)]. A neuraminidase inhibition assay was used to determine the Inhibitory Concentration 50 (IC₅₀) values for all influenza A and B isolates.

Results: There were 341 influenza A positive samples identified; influenza A(H1N1)pdm09 was identified most frequently (n = 215). In 2009, oseltamivir resistance was observed in 100% (19 of 19) of seasonal A(H1N1) isolates and 1.4% (3/215) of A(H1N1)pdm09 isolates. This H275Y mutation was not found in influenza subtypes A(H5N1) or A(H3N2) isolates.

Discussion: In Viet Nam, seasonal and A(H5N1) influenza vaccines are not currently available; thus, effective treatment is required. The presence of oseltamivir-resistant viruses is therefore a concern. Active surveillance for oseltamivir resistance among influenza viruses circulating in Viet Nam should be continued.
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http://dx.doi.org/10.5365/WPSAR.2013.4.1.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3762967PMC
September 2015

The epidemiology of interpandemic and pandemic influenza in Vietnam, 2007-2010: the Ha Nam household cohort study I.

Am J Epidemiol 2012 May 12;175(10):1062-74. Epub 2012 Mar 12.

Oxford University Clinical Research Unit, National Hospital of Tropical Diseases, 78 Giai Phong Street, Dong Da District, Hanoi, Vietnam.

Prospective community-based studies have provided fundamental insights into the epidemiology of influenza in temperate regions, but few comparable studies have been undertaken in the tropics. The authors conducted prospective influenza surveillance and intermittent seroprevalence surveys in a household-based cohort in Vietnam between December 2007 and April 2010, resulting in 1,793 person-seasons of influenza surveillance. Age- and sex-standardized estimates of the risk of acquiring any influenza infection per season in persons 5 years of age or older were 21.1% (95% confidence interval: 17.4, 24.7) in season 1, 26.4% (95% confidence interval: 22.6, 30.2) in season 2, and 17.0% (95% confidence interval: 13.6, 20.4) in season 3. Some individuals experienced multiple episodes of infection with different influenza types/subtypes in the same season (n = 27) or reinfection with the same subtype in different seasons (n = 22). The highest risk of influenza infection was in persons 5-9 years old, in whom the risk of influenza infection per season was 41.8%. Although the highest infection risk was in school-aged children, there were important heterogeneities in the age of infection by subtype and season. These heterogeneities could influence the impact of school closure and childhood vaccination on influenza transmission in tropical areas, such as Vietnam.
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http://dx.doi.org/10.1093/aje/kws121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3353138PMC
May 2012