Publications by authors named "Nguyen Tran Hien"

74 Publications

Increasing HIV prevalence and injection drug use among men who have sex with men in Ho Chi Minh City, Vietnam.

Int J STD AIDS 2020 Nov 30;31(13):1247-1254. Epub 2020 Sep 30.

U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA.

Vietnam has been conducting HIV/sexually transmitted infection (STI) integrated bio-behavioral surveillance surveys on men who have sex with men (MSM) as well as other key populations since 2005. Although HIV prevalence in the Vietnamese general population remains below 1%, it is expected to be much higher among MSM.Data on HIV prevalence and sexual and drug use behaviors were collected from MSM in Ho Chi Minh City (HCMC) in 2006 (n = 397), 2009 (n = 399) and 2013 (n = 350) using respondent-driven sampling. Eligible participants were males, aged ≥15 years who reported having manual, oral, or anal sexual activity with males in the past year and lived, worked or socialized in HCMC.HIV seroprevalence among MSM was 5.8% in 2006, 16.1% in 2009 and 12.1% in 2013 and prevalence of at least one STI (syphilis, gonorrhea and/or chlamydia infection) was 11.4% in 2006 and 15.6% in 2009 (no data for 2013). Significant, but small, increasing trends were found for MSM who reported ever testing and receiving results for HIV and for HIV prevalence. No significant changes for condom use, injecting and non-injecting drug use, or and receipt of free condoms were observed.Although a small percentage of MSM reported injecting drugs, HIV was positively associated with ever injecting drugs. Programs targeting MSM should include screening and treatment for injection drug use to most effectively control the HIV/AIDS epidemic among MSM in HCMC.
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http://dx.doi.org/10.1177/0956462420947555DOI Listing
November 2020

Evaluating an intervention for family members of people who use drugs in Vietnam.

Soc Sci Med 2020 09 23;261:113238. Epub 2020 Jul 23.

National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam.

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http://dx.doi.org/10.1016/j.socscimed.2020.113238DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7484146PMC
September 2020

Epidemiological and comparative genomic analysis of Bacillus anthracis isolated from northern Vietnam.

PLoS One 2020 21;15(2):e0228116. Epub 2020 Feb 21.

Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan.

To understand the epidemiological and genetic background of anthrax cases occurring in Vietnam from 2011 to 2015, we surveilled and genetically analyzed Bacillus anthracis isolated in the north of the country. Epidemiological surveillance showed that most human cutaneous anthrax cases occurred in association with animal dissection. Whole-genome sequences were obtained from six B. anthracis strains from human patients with cutaneous anthrax in the endemic area. Comparative genomic analysis showed that the genetic homogeneity among Vietnamese B. anthracis strains was very high. All Vietnamese B. anthracis strains belonged to the canSNP lineage of A.Br.011/009, which mostly consists of strains of the trans-Eurasian (TEA) group, including the most closely related strain, Carbosap. To clarify the genetic diversity of Vietnamese strains and strains belonging to A.Br.011/009 and A.Br.008/011 canSNP lineages, we applied a reference genome-based single-nucleotide polymorphism (SNP) and gene-by-gene genomic analysis (whole-genome MLST) strategy. The phylogeny from core genome SNPs revealed that the Vietnamese strains were positioned close to each other; moreover, several SNPs specific to Vietnamese B. anthracis were identified. Whole-genome MLST analysis revealed the differences in the number of SNPs between Vietnamese strains, which could enable discrimination at the strain level.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228116PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7034820PMC
April 2020

Plans for Nationwide Serosurveillance Network in Vietnam.

Emerg Infect Dis 2020 01;26(1)

In recent years, serosurveillance has gained momentum as a way of determining disease transmission and immunity in populations, particularly with respect to vaccine-preventable diseases. At the end of 2017, the Oxford University Clinical Research Unit and the National Institute of Hygiene and Epidemiology held a meeting in Vietnam with national policy makers, researchers, and international experts to discuss current seroepidemiologic projects in Vietnam and future needs and plans for nationwide serosurveillance. This report summarizes the meeting and the plans that were discussed to set up nationwide serosurveillance in Vietnam.
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http://dx.doi.org/10.3201/eid2601.190641DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6924907PMC
January 2020

Tuberculosis risk factors and Mycobacterium tuberculosis transmission among HIV-infected patients in Vietnam.

Tuberculosis (Edinb) 2019 03 7;115:67-75. Epub 2019 Feb 7.

Sydney Medical School and Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Australia; Centre for Infectious Diseases and Microbiology - Public Health, ICPMR, Westmead Hospital, Sydney, Australia.

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http://dx.doi.org/10.1016/j.tube.2019.02.001DOI Listing
March 2019

Sero-Prevalence Surveillance to Predict Vaccine-Preventable Disease Outbreaks; A Lesson from the 2014 Measles Epidemic in Northern Vietnam.

Open Forum Infect Dis 2019 Mar 24;6(3):ofz030. Epub 2019 Jan 24.

Oxford University Clinical Research Unit, Wellcome Trust Asia Programme, Hanoi, Vietnam.

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.
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http://dx.doi.org/10.1093/ofid/ofz030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6405937PMC
March 2019

Drug Resistance and Transmission among Human Immunodeficiency Virus-Infected Patients in Ho Chi Minh City, Vietnam.

Am J Trop Med Hyg 2018 12;99(6):1397-1406

Centre for Infectious Disease and Microbiology-Public Health, ICPMR, Westmead Hospital, Sydney, Australia.

Vietnam has a high burden of tuberculosis (TB) and multidrug-resistant (MDR) TB, but drug resistance patterns and TB transmission dynamics among TB/human immunodeficiency virus (HIV) coinfected patients are not well described. We characterized 200 isolates from TB/HIV coinfected patients diagnosed at the main TB referral hospital in Ho Chi Minh City, Vietnam. Phenotypic drug susceptibility testing (DST) for first-line drugs, spoligotyping, and 24-locus mycobacterial interspersed repetitive unit (MIRU-24) analysis was performed on all isolates. The 24-locus mycobacterial interspersed repetitive unit clusters and MDR isolates were subjected to whole genome sequencing (WGS). Most of the TB/HIV coinfected patients were young (162/174; 93.1% aged < 45 years) males (173; 86.5% male). Beijing (98; 49.0%) and Indo-Oceanic (70; 35.0%) lineage strains were most common. Phenotypic drug resistance was detected in 84 (42.0%) isolates, of which 17 (8.5%) were MDR; three additional MDR strains were identified on WGS. Strain clustering was reduced from 84.0% with spoligotyping to 20.0% with MIRU-24 typing and to 13.5% with WGS. Whole genome sequencing identified five additional clusters, or members of clusters, not recognized by MIRU-24. In total, 13 small (two to three member) WGS clusters were identified, with less clustering among drug susceptible (2/27; 7.4%) than among drug-resistant strains (25/27; 92.6%). On phylogenetic analysis, strains from TB/HIV coinfected patients were interspersed among strains from the general community; no major clusters indicating transmission among people living with HIV were detected. Tuberculosis/HIV coinfection in Vietnam was associated with high rates of drug resistance and limited genomic evidence of ongoing transmission among HIV-infected patients.
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http://dx.doi.org/10.4269/ajtmh.18-0185DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6283501PMC
December 2018

Viral load suppression and acquired HIV drug resistance in adults receiving antiretroviral therapy in Viet Nam: results from a nationally representative survey.

Western Pac Surveill Response J 2018 Jul-Sep;9(3):16-24. Epub 2018 Aug 20.

World Health Organization Viet Nam Country Office, Hanoi, Vietnam.

Objective: The purpose of this survey was to estimate the prevalence of viral load (VL) suppression and emergence of HIV drug resistance (HIVDR) among individuals receiving antiretroviral therapy (ART) for 36 months or longer in Viet Nam using a nationally representative sampling method.

Methods: The survey was conducted between May and August 2014 using a two-stage cluster design. Sixteen ART clinics were selected using probability proportional to proxy size sampling, and patients receiving ART for at least 36 months were consecutively enrolled. Epidemiological information and blood specimens were collected for HIV-1 VL and HIVDR testing; HIVDR was defined by the Stanford University HIVDR algorithm.

Results: Overall, 365 eligible individuals were recruited with a mean age of 38.2 years; 68.4% were men. The mean time on ART was 75.5 months (95% confidence interval [CI]: 69.0-81.9 months), and 93.7% of the patients were receiving non-nucleoside reverse transcriptase inhibitor-based regimens. Of the 365 individuals, 345 (94.7%, 95% CI: 64.1-99.4%) had VL below 1000 copies/mL and 19 (4.6%, 95% CI: 2.8--7.5) had HIVDR mutations.

Discussion: Our nationally representative survey found a high level of VL suppression and a low prevalence of HIVDR among individuals who received ART for at least 36 months in Viet Nam. Continued surveillance for HIVDR is important for evaluating and improving HIV programs.
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http://dx.doi.org/10.5365/wpsar.2018.9.1.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6194224PMC
November 2018

Efficacy of Communication Training of Community Health Workers on Service Delivery to People Who Inject Drugs in Vietnam: A Clustered Randomized Trial.

Am J Public Health 2018 06 19;108(6):791-798. Epub 2018 Apr 19.

Li Li, Li-Jung Liang, Chunqing Lin, Chiao-Wen Lan, and Sung-Jae Lee are with the Semel Institute for Neuroscience and Human Behavior, Center for Community Health, University of California, Los Angeles. Nguyen Tran Hien, Nguyen Anh Tuan, Le Anh Tuan, Duong Cong Thanh, and Nguyen Thi Thanh Ha are with the HIV/AIDS Department, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.

Objectives: To evaluate the efficacy of an intervention targeted to commune health workers (CHWs) who deliver services to people who inject drugs (PWID) in Vietnam.

Methods: From 2014 to 2016, we conducted a cluster randomized controlled trial of 300 CHWs and 900 PWID in 60 communes in 2 provinces of Vietnam. Intervention CHWs participated in training sessions to enhance their communication skills. Trained CHWs were asked to deliver individual sessions to PWID. We assessed the outcomes at baseline and at 3-, 6-, 9-, and 12-month follow-ups.

Results: Intervention CHWs showed greater improvement in provider-client interactions than did control CHWs at all follow-ups (range of difference = 3.33-5.18; P < .001). Intervention CHWs showed greater reduction in negative attitudes toward PWID at the 12-month follow-up (mean ±SD = 1.75 ±0.50; P < .001). PWID in the intervention group exhibited greater improvement in drug avoidance than did those in the control group from the 6-month follow-up on (range of difference = 1.21-1.65; P < .001). We observed no intervention effect on heroin use as measured by urinalysis.

Conclusions: This intervention targeting CHWs could lead to desired outcomes for both CHWs and PWID. ClinicalTrials.gov: NCT0213092.1.
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http://dx.doi.org/10.2105/AJPH.2018.304350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5944870PMC
June 2018

Epidemiological, Serological, and Virological Features of Dengue in Nha Trang City, Vietnam.

Am J Trop Med Hyg 2018 02 4;98(2):402-409. Epub 2018 Jan 4.

Institute for Vector Borne Disease, Monash University, Clayton, Australia.

Vietnam is endemic for dengue. We conducted a series of retrospective and prospective studies to characterize the epidemiology of dengue and population mobility patterns in Nha Trang city, Vietnam, with a view to rational design of trials of community-level interventions. A 10-year time series of dengue case notifications showed pronounced interannual variability, as well as spatial heterogeneity in ward-level dengue incidence (median annual coefficient of variation = 0.47). Of 451 children aged 1-10 years enrolled in a cross-sectional serosurvey, almost one-third had evidence of a past dengue virus (DENV) infection, with older children more likely to have a multitypic response indicative of past exposure to ≥ 1 serotype. All four DENV serotypes were detected in hospitalized patients during 8 months of sampling in 2015. Mobility data collected from 1,000 children and young adults via prospective travel diaries showed that, although all ages spent approximately half of their daytime hours (5:00 am-9:00 pm) at home, younger age groups (≤ 14 years) spent a significantly greater proportion of their time within 500 m of home than older respondents. Together these findings inform the rational design of future trials of dengue preventive interventions in this setting by identifying 1) children < 7 years as an optimal target group for a flavivirus-naive serological cohort, 2) children and young adults as the predominant patient population for a study with a clinical end point of symptomatic dengue, and 3) substantial spatial and temporal variations in DENV transmission, with a consequent requirement for a trial to be large enough and of long enough duration to overcome this heterogeneity.
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http://dx.doi.org/10.4269/ajtmh.17-0630DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5929208PMC
February 2018

Highly Pathogenic Avian Influenza A(H5N1) Viruses at the Animal-Human Interface in Vietnam, 2003-2010.

J Infect Dis 2017 09;216(suppl_4):S529-S538

Influenza Division, Centers for Disease Control and Prevention.

Mutation and reassortment of highly pathogenic avian influenza A(H5N1) viruses at the animal-human interface remain a major concern for emergence of viruses with pandemic potential. To understand the relationship of H5N1 viruses circulating in poultry and those isolated from humans, comprehensive phylogenetic and molecular analyses of viruses collected from both hosts in Vietnam between 2003 and 2010 were performed. We examined the temporal and spatial distribution of human cases relative to H5N1 poultry outbreaks and characterized the genetic lineages and amino acid substitutions in each gene segment identified in humans relative to closely related viruses from avian hosts. Six hemagglutinin clades and 8 genotypes were identified in humans, all of which were initially identified in poultry. Several amino acid mutations throughout the genomes of viruses isolated from humans were identified, indicating the potential for poultry viruses infecting humans to rapidly acquire molecular markers associated with mammalian adaptation and antiviral resistance.
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http://dx.doi.org/10.1093/infdis/jix003DOI Listing
September 2017

Drug resistance and Mycobacterium tuberculosis strain diversity in TB/HIV co-infected patients in Ho Chi Minh city, Vietnam.

J Glob Antimicrob Resist 2017 09 22;10:154-160. Epub 2017 Jul 22.

Sydney Medical School and Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, Australia; Centre for Infectious Disease and Microbiology - Public Health, ICPMR, Westmead Hospital, Sydney, Australia.

Background: Mycobacterium tuberculosis strain diversity and drug resistance among people living with human immunodeficiency virus (HIV) in Vietnam have not been described previously.

Methods: We examined M. tuberculosis isolates from TB/HIV co-infected patients in Ho Chi Minh City, Vietnam. Drug susceptibility testing (DST), spoligotyping and 24-locus Mycobacterial Interspersed Repetitive Unit (MIRU-24 typing) were performed, and the rpoB, katG, inhA and inhA promoter, rpsL, rrs and embB genes were sequenced in all drug resistant isolates identified.

Results: In total, 84/200 (42.0%) strains demonstrated "any drug resistance"; 17 (8.5%) were multi-drug resistant (MDR). Streptomycin resistance was present in 80 (40.0%) isolates; 95.2% (80/84) with "any drug resistance" and 100% with MDR. No rifampicin monoresistance was detected. Of the rifampicin resistant strains 16/18 (88.9%) had mutations in the 81-bp Rifampicin Resistance Defining Region (RRDR) of the rpoB gene. Isoniazid resistance was mostly associated with Ser315Thr mutations in the katG gene (15/17; 88.2%). Beijing (49.0%) and East African Indian (EAI) lineage strains (35.0%; 56/70 EAI-5) were most common.

Conclusion: TB/HIV co-infection in Vietnam was associated with high rates of TB drug resistance, although we were unable to differentiate new from retreatment cases.
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http://dx.doi.org/10.1016/j.jgar.2017.07.003DOI Listing
September 2017

Valine/isoleucine variants drive selective pressure in the VP1 sequence of EV-A71 enteroviruses.

BMC Infect Dis 2017 05 8;17(1):333. Epub 2017 May 8.

Cirad, UMR 17, Intertryp, TA-A17/G, Campus International de Baillarguet, 34398, Montpellier Cedex 5, France.

Background: In 2011-2012, Northern Vietnam experienced its first large scale hand foot and mouth disease (HFMD) epidemic. In 2011, a major HFMD epidemic was also reported in South Vietnam with fatal cases. This 2011-2012 outbreak was the first one to occur in North Vietnam providing grounds to study the etiology, origin and dynamic of the disease. We report here the analysis of the VP1 gene of strains isolated throughout North Vietnam during the 2011-2012 outbreak and before.

Methods: The VP1 gene of 106 EV-A71 isolates from North Vietnam and 2 from Central Vietnam were sequenced. Sequence alignments were analyzed at the nucleic acid and protein level. Gene polymorphism was also analyzed. A Factorial Correspondence Analysis was performed to correlate amino acid mutations with clinical parameters.

Results: The sequences were distributed into four phylogenetic clusters. Three clusters corresponded to the subgenogroup C4 and the last one corresponded to the subgenogroup C5. Each cluster displayed different polymorphism characteristics. Proteins were highly conserved but three sites bearing only Isoleucine (I) or Valine (V) were characterized. The isoleucine/valine variability matched the clusters. Spatiotemporal analysis of the I/V variants showed that all variants which emerged in 2011 and then in 2012 were not the same but were all present in the region prior to the 2011-2012 outbreak. Some correlation was found between certain I/V variants and ethnicity and severity.

Conclusions: The 2011-2012 outbreak was not caused by an exogenous strain coming from South Vietnam or elsewhere but by strains already present and circulating at low level in North Vietnam. However, what triggered the outbreak remains unclear. A selective pressure is applied on I/V variants which matches the genetic clusters. I/V variants were shown on other viruses to correlate with pathogenicity. This should be investigated in EV-A71. I/V variants are an easy and efficient way to survey and identify circulating EV-A71 strains.
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http://dx.doi.org/10.1186/s12879-017-2427-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5422960PMC
May 2017

Estimating False-Recent Classification for the Limiting-Antigen Avidity EIA and BED-Capture Enzyme Immunoassay in Vietnam: Implications for HIV-1 Incidence Estimates.

AIDS Res Hum Retroviruses 2017 06 13;33(6):546-554. Epub 2017 Mar 13.

1 Centers for Disease Control and Prevention , Atlanta, Georgia .

Laboratory tests that can distinguish recent from long-term HIV infection are used to estimate HIV incidence in a population, but can potentially misclassify a proportion of long-term HIV infections as recent. Correct application of an assay requires determination of the proportion false recents (PFRs) as part of the assay characterization and for calculating HIV incidence in a local population using a HIV incidence assay. From April 2009 to December 2010, blood specimens were collected from HIV-infected individuals attending nine outpatient clinics (OPCs) in Vietnam (four from northern and five from southern Vietnam). Participants were living with HIV for ≥1 year and reported no antiretroviral (ARV) drug treatment. Basic demographic data and clinical information were collected. Specimens were tested with the BED capture enzyme immunoassay (BED-CEIA) and the Limiting-antigen (LAg)-Avidity EIA. PFR was estimated by dividing the number of specimens classified as recent by the total number of specimens; 95% confidence intervals (CI) were calculated. Specimens that tested recent had viral load testing performed. Among 1,813 specimens (north, n = 942 and south, n = 871), the LAg-Avidity EIA PFR was 1.7% (CI: 1.2-2.4) and differed by region [north 2.7% (CI: 1.8-3.9) versus south 0.7% (CI: 0.3-1.5); p = .002]. The BED-CEIA PFR was 2.3% (CI: 1.7-3.0) and varied by region [north 3.4% (CI: 2.4-4.7) versus south 1.0% (CI: 0.5-1.2), p < .001]. Excluding specimens with an undetectable VL, the LAg-Avidity EIA PFR was 1.2% (CI: 0.8-1.9) and the BED-CEIA PFR was 1.7% (CI: 1.2-2.4). The LAg-Avidity EIA PFR was lower than the BED-CEIA PFR. After excluding specimens with an undetectable VL, the PFR for both assays was similar. A low PFR should facilitate the implementation of the LAg-Avidity EIA for cross-sectional incidence estimates in Vietnam.
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http://dx.doi.org/10.1089/AID.2016.0203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5745576PMC
June 2017

Global Role and Burden of Influenza in Pediatric Respiratory Hospitalizations, 1982-2012: A Systematic Analysis.

PLoS Med 2016 Mar 24;13(3):e1001977. Epub 2016 Mar 24.

National Institute for Communicable Diseases, Johannesburg, South Africa.

Background: The global burden of pediatric severe respiratory illness is substantial, and influenza viruses contribute to this burden. Systematic surveillance and testing for influenza among hospitalized children has expanded globally over the past decade. However, only a fraction of the data has been used to estimate influenza burden. In this analysis, we use surveillance data to provide an estimate of influenza-associated hospitalizations among children worldwide.

Methods And Findings: We aggregated data from a systematic review (n = 108) and surveillance platforms (n = 37) to calculate a pooled estimate of the proportion of samples collected from children hospitalized with respiratory illnesses and positive for influenza by age group (<6 mo, <1 y, <2 y, <5 y, 5-17 y, and <18 y). We applied this proportion to global estimates of acute lower respiratory infection hospitalizations among children aged <1 y and <5 y, to obtain the number and per capita rate of influenza-associated hospitalizations by geographic region and socio-economic status. Influenza was associated with 10% (95% CI 8%-11%) of respiratory hospitalizations in children <18 y worldwide, ranging from 5% (95% CI 3%-7%) among children <6 mo to 16% (95% CI 14%-20%) among children 5-17 y. On average, we estimated that influenza results in approximately 374,000 (95% CI 264,000 to 539,000) hospitalizations in children <1 y-of which 228,000 (95% CI 150,000 to 344,000) occur in children <6 mo-and 870,000 (95% CI 610,000 to 1,237,000) hospitalizations in children <5 y annually. Influenza-associated hospitalization rates were more than three times higher in developing countries than in industrialized countries (150/100,000 children/year versus 48/100,000). However, differences in hospitalization practices between settings are an important limitation in interpreting these findings.

Conclusions: Influenza is an important contributor to respiratory hospitalizations among young children worldwide. Increasing influenza vaccination coverage among young children and pregnant women could reduce this burden and protect infants <6 mo.
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http://dx.doi.org/10.1371/journal.pmed.1001977DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4807087PMC
March 2016

Seasonality of absolute humidity explains seasonality of influenza-like illness in Vietnam.

Epidemics 2015 Dec 28;13:65-73. Epub 2015 Aug 28.

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

Background: Experimental and ecological studies have shown the role of climatic factors in driving the epidemiology of influenza. In particular, low absolute humidity (AH) has been shown to increase influenza virus transmissibility and has been identified to explain the onset of epidemics in temperate regions. Here, we aim to study the potential climatic drivers of influenza-like illness (ILI) epidemiology in Vietnam, a tropical country characterized by a high diversity of climates. We specifically focus on quantifying and explaining the seasonality of ILI.

Methods: We used 18 years (1993-2010) of monthly ILI notifications aggregated by province (52) and monthly climatic variables (minimum, mean, maximum temperatures, absolute and relative humidities, rainfall and hours of sunshine) from 67 weather stations across Vietnam. Seasonalities were quantified from global wavelet spectra, using the value of the power at the period of 1 year as a measure of the intensity of seasonality. The 7 climatic time series were characterized by 534 summary statistics which were entered into a regression tree to identify factors associated with the seasonality of AH. Results were extrapolated to the global scale using simulated climatic times series from the NCEP/NCAR project.

Results: The intensity of ILI seasonality in Vietnam is best explained by the intensity of AH seasonality. We find that ILI seasonality is weak in provinces experiencing weak seasonal fluctuations in AH (annual power <17.6), whereas ILI seasonality is strongest in provinces with pronounced AH seasonality (power >17.6). In Vietnam, AH and ILI are positively correlated.

Conclusions: Our results identify a role for AH in driving the epidemiology of ILI in a tropical setting. However, in contrast to temperate regions, high rather than low AH is associated with increased ILI activity. Fluctuation in AH may be the climate factor that underlies and unifies the seasonality of ILI in both temperate and tropical regions. Alternatively, the mechanism of action of AH on disease transmission may be different in cold-dry versus hot-humid settings.
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http://dx.doi.org/10.1016/j.epidem.2015.06.002DOI Listing
December 2015

Field evaluation of the establishment potential of wMelPop Wolbachia in Australia and Vietnam for dengue control.

Parasit Vectors 2015 Oct 28;8:563. Epub 2015 Oct 28.

Bio21 Institute and School of BioSciences, University of Melbourne, Parkville, Australia.

Background: Introduced Wolbachia bacteria can influence the susceptibility of Aedes aegypti mosquitoes to arboviral infections as well as having detrimental effects on host fitness. Previous field trials demonstrated that the wMel strain of Wolbachia effectively and durably invades Ae. aegypti populations. Here we report on trials of a second strain, wMelPop-PGYP Wolbachia, in field sites in northern Australia (Machans Beach and Babinda) and central Vietnam (Tri Nguyen, Hon Mieu Island), each with contrasting natural Ae. aegypti densities.

Methods: Mosquitoes were released at the adult or pupal stages for different lengths of time at the sites depending on changes in Wolbachia frequency as assessed through PCR assays of material collected through Biogents-Sentinel (BG-S) traps and ovitraps. Adult numbers were also monitored through BG-S traps. Changes in Wolbachia frequency were compared across hamlets or house blocks.

Results: Releases of adult wMelPop-Ae. aegypti resulted in the transient invasion of wMelPop in all three field sites. Invasion at the Australian sites was heterogeneous, reflecting a slower rate of invasion in locations where background mosquito numbers were high. In contrast, invasion across Tri Nguyen was relatively uniform. After cessation of releases, the frequency of wMelPop declined in all sites, most rapidly in Babinda and Tri Nguyen. Within Machans Beach the rate of decrease varied among areas, and wMelPop was detected for several months in an area with a relatively low mosquito density.

Conclusions: These findings highlight challenges associated with releasing Wolbachia-Ae. aegypti combinations with low fitness, albeit strong virus interference properties, as a means of sustainable control of dengue virus transmission.
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http://dx.doi.org/10.1186/s13071-015-1174-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625535PMC
October 2015

An outbreak of influenza A(H1N1)pdm09 virus in a primary school in Vietnam.

BMC Res Notes 2015 Oct 15;8:572. Epub 2015 Oct 15.

World Health Organization, Hanoi, Vietnam.

Background: Despite school pupils being at greatest risk during the 2009 influenza pandemic there are limited data on outbreaks of influenza A(H1N1)pdm09 in primary schools in South-East Asia. This prospective cohort study describes an outbreak of influenza A(H1N1)pdm09 in a primary school in rural Vietnam.

Findings: In total 103 cases of influenza-like illness were found among the 407 pupils in the primary school. Ten of these were laboratory confirmed cases of influenza A(H1N1)pdm09 virus. The overall attack rate (AR) was 25% (103/407), and was highest (41%) in grade 4 pupils, where the outbreak started. All cases in the outbreak presented with a mild and self-limiting illness, acute respiratory symptoms and fever. Public health interventions to contain the outbreak could explain the lower attack rates in other grades. Ill pupils were asked to stay at home. Oseltamivir was not given to pupils and the school did not close during the outbreak. The last detected case occurred 12 days following identification of the first case.

Conclusions: This is the first report of an outbreak of influenza A(H1N1)pdm09 among pupils in a primary school in Vietnam. High attack rates in Grade 4 pupils suggest shared activities contributed to transmission. The public health response using non-pharmaceutical measures may have played a role in ending the outbreak.
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http://dx.doi.org/10.1186/s13104-015-1551-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4608302PMC
October 2015

Region-wide synchrony and traveling waves of dengue across eight countries in Southeast Asia.

Proc Natl Acad Sci U S A 2015 Oct 5;112(42):13069-74. Epub 2015 Oct 5.

Department of Biology, University of Florida, Gainesville, FL 32610; Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610.

Dengue is a mosquito-transmitted virus infection that causes epidemics of febrile illness and hemorrhagic fever across the tropics and subtropics worldwide. Annual epidemics are commonly observed, but there is substantial spatiotemporal heterogeneity in intensity. A better understanding of this heterogeneity in dengue transmission could lead to improved epidemic prediction and disease control. Time series decomposition methods enable the isolation and study of temporal epidemic dynamics with a specific periodicity (e.g., annual cycles related to climatic drivers and multiannual cycles caused by dynamics in population immunity). We collected and analyzed up to 18 y of monthly dengue surveillance reports on a total of 3.5 million reported dengue cases from 273 provinces in eight countries in Southeast Asia, covering ∼ 10(7) km(2). We detected strong patterns of synchronous dengue transmission across the entire region, most markedly during a period of high incidence in 1997-1998, which was followed by a period of extremely low incidence in 2001-2002. This synchrony in dengue incidence coincided with elevated temperatures throughout the region in 1997-1998 and the strongest El Niño episode of the century. Multiannual dengue cycles (2-5 y) were highly coherent with the Oceanic Niño Index, and synchrony of these cycles increased with temperature. We also detected localized traveling waves of multiannual dengue epidemic cycles in Thailand, Laos, and the Philippines that were dependent on temperature. This study reveals forcing mechanisms that drive synchronization of dengue epidemics on a continental scale across Southeast Asia.
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http://dx.doi.org/10.1073/pnas.1501375112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4620875PMC
October 2015

A dengue outbreak on a floating village at Cat Ba Island in Vietnam.

BMC Public Health 2015 Sep 22;15:940. Epub 2015 Sep 22.

Oxford University Clinical Research Unit Hanoi, Hanoi, Vietnam.

Background: A dengue outbreak in an ecotourism destination spot in Vietnam, from September to November 2013, impacted a floating village of fishermen on the coastal island of Cat Ba. The outbreak raises questions about how tourism may impact disease spread in rural areas.

Methods: Epidemiological data were obtained from the Hai Phong Preventive Medical Center (PMC), including case histories and residential location from all notified dengue cases from this outbreak. All household addresses were geo-located. Knox test, a spatio-temporal analysis that enables inference dengue clustering constrained by space and time, was performed on the geocoded locations. From the plasma available from two patients, positive for Dengue serotype 3 virus (DENV3), the Envelope (E) gene was sequenced, and their genetic relationships compared to other E sequences in the region.

Results: Of 192 dengue cases, the odds ratio of contracting dengue infections for people living in the floating villages compared to those living on the island was 4.9 (95 % CI: 3.6-6.7). The space-time analyses on 111 geocoded dengue residences found the risk of dengue infection to be the highest within 4 days and a radius of 20 m of a given case. Of the total of ten detected clusters with an excess risk greater than 2, the cluster with the highest number of cases was in the floating village area (24 patients for a total duration of 31 days). Phylogenetic analysis revealed a high homology of the two DENV3 strains (genotype III) from Cat Ba with DENV3 viruses circulating in Hanoi in the same year (99.1 %).

Conclusions: Our study showed that dengue transmission is unlikely to be sustained on Cat Ba Island and that the 2013 epidemic likely originated through introduction of viruses from the mainland, potentially Hanoi. These findings suggest that prevention efforts should be focused on mainland rather than on the island.
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http://dx.doi.org/10.1186/s12889-015-2235-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4579793PMC
September 2015

Modeling the impact of rubella vaccination in Vietnam.

Hum Vaccin Immunother 2016 ;12(1):150-8

d National Institute of Hygiene and Epidemiology ; Hanoi , Vietnam.

Supported by GAVI Alliance, measles-rubella vaccination was introduced in Vietnam in 2014, involving a mass campaign among 1-14 year olds and routine immunization of children aged 9 months. We explore the impact on the incidence of Congenital Rubella Syndrome (CRS) during 2013-2050 of this strategy and variants involving women aged 15-35 years. We use an age and sex-structured dynamic transmission model, set up using recently-collected seroprevalence data from Central Vietnam, and also consider different levels of transmission and contact patterns. If the serological profile resembles that in Central Vietnam, the planned vaccination strategy could potentially prevent 125,000 CRS cases by 2050 in Vietnam, despite outbreaks predicted in the meantime. Targeting the initial campaign at 15-35 year old women with or without children aged 9 months-14 years led to sustained reductions in incidence, unless levels of ongoing transmission were medium-high before vaccination started. Assumptions about contact greatly influenced predictions if the initial campaign just targeted 15-35 year old women and/or levels of ongoing transmission were medium-high. Given increased interest in rubella vaccination, resulting from GAVI Alliance funding, the findings are relevant for many countries.
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http://dx.doi.org/10.1080/21645515.2015.1060380DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002053PMC
December 2016

Practices around the use of masks and respirators among hospital health care workers in 3 diverse populations.

Am J Infect Control 2015 Oct 13;43(10):1116-8. Epub 2015 Jul 13.

School of Public Health and Community Medicine, UNSW Medicine, University of New South Wales, Sydney, NSW, Australia.

A cross-sectional survey was conducted in 89 secondary- and tertiary-level hospitals in 3 countries, and samples of masks and respirators were also collected and examined. Results showed varied practices around the use of masks and respirators, which are probably influenced by the available resources and local recommendations. Nonstandardized practices are common in low-resource settings, which may be placing health care workers at risk.
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http://dx.doi.org/10.1016/j.ajic.2015.05.041DOI Listing
October 2015

Congenital rubella syndrome (CRS) in Vietnam 2011-2012--CRS epidemic after rubella epidemic in 2010-2011.

Vaccine 2015 Jul 15;33(31):3673-7. Epub 2015 Jun 15.

National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam.

Background: Rubella is endemic in Vietnam with epidemics occurring every 4-5 years. In 2011, Vietnam experienced the large nationwide rubella epidemic. During the rubella epidemic, many infants born with congenital rubella syndrome (CRS) were identified and reported from the neonatal units or cardiology departments of the national hospitals. To understand the burden of CRS, National Expanded Program on Immunization (NEPI) established sentinel CRS surveillance system.

Method: Three national paediatric hospitals in Hanoi and Ho Chi Minh City (HCMC) were selected as CRS sentinel surveillance sites. Blood specimens from the infants were collected for rubella specific IgM and ELISA testing was performed at the national measles and rubella laboratory.

Results: From January 2011 to December 2012, 424 infants with suspected CRS were identified and reported. Among them 406 (96%) had specimens obtained, 284 (70%) cases were IgM positive including 279 laboratory confirmed CRS and 5 Congenital Rubella Infection (CRI). 13 cases were clinically confirmed and 127 (30%) were discarded. Total 292 infants were confirmed as CRS. Of the 292 infants with CRS, 69% of mothers had a history of "fever and rash" during pregnancy, of which 85% was in the first trimester. The most common clinical defects were congenital heart disease and cataract(s). However, 81.9% of the infants had a combination of major and minor signs and symptoms. Low birth weight in full term infants with confirmed CRS was observed in 114 infants (39%).

Conclusions: The newly established CRS sentinel surveillance system documented the significant burden of CRS in Vietnam and provided evidence to the policy makers for the introduction of rubella containing vaccine (RCV) into Vietnam. This report highlights the importance of countries with rubella epidemic to establish CRS surveillance rapidly in order to support the introduction of RCV into the routine Expanded Programme on Immunization (EPI) immunization.
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http://dx.doi.org/10.1016/j.vaccine.2015.06.035DOI Listing
July 2015

Impact of Adverse Events Following Immunization in Viet Nam in 2013 on chronic hepatitis B infection.

Vaccine 2016 Feb 6;34(6):869-73. Epub 2015 Jun 6.

National Institute of Hygiene and Epidemiology, 1 Yersin Street, Hai Ba Trung, Ha Noi 10000, Viet Nam.

Adverse Events Following Immunization in Viet Nam in 2013 led to substantial reductions in hepatitis B vaccination coverage (both the birth dose and the three-dose series). In order to estimate the impact of the reduction in vaccination coverage on hepatitis B transmission and future mortality, a widely-used mathematical model was applied to the data from Viet Nam. Using the model, we estimated the number of chronic infections and deaths that are expected to occur in the birth cohort in 2013 and the number of excessive infections and deaths attributable to the drop in immunization coverage in 2013. An excess of 90,137 chronic infections and 17,456 future deaths were estimated to occur in the 2013 birth cohort due to the drop in vaccination coverage. This analysis highlights the importance of maintaining high vaccination coverage and swiftly responding to reported Adverse Events Following Immunization in order to regain consumer confidence in the hepatitis B vaccine.
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http://dx.doi.org/10.1016/j.vaccine.2015.05.067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5357724PMC
February 2016

Brief behavioural surveys in routine HIV sentinel surveillance: a new tool for monitoring the HIV epidemic in Viet Nam.

Western Pac Surveill Response J 2015 Jan-Mar;6(1):52-4. Epub 2015 Jan 27.

Office of the WHO Representative Office in Viet Nam, Ha Noi, Viet Nam .

In this report we describe a new approach in HIV sentinel surveillance that was piloted in Viet Nam in 2009 and is currently being rolled out in all provinces. It comprises a brief behavioural questionnaire added to the HIV sentinel surveillance surveys conducted routinely among people who inject drugs, female sex workers and men who have sex with men. Timely reporting of data from this system has resulted in improvements to HIV prevention efforts for most at-risk populations.
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http://dx.doi.org/10.2471/WPSAR.2015.6.1-052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4410099PMC
January 2016

Differences in the Epidemiology of Human Cases of Avian Influenza A(H7N9) and A(H5N1) Viruses Infection.

Clin Infect Dis 2015 Aug 4;61(4):563-71. Epub 2015 May 4.

Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.

Background: The pandemic potential of avian influenza viruses A(H5N1) and A(H7N9) remains an unresolved but critically important question.

Methods: We compared the characteristics of sporadic and clustered cases of human H5N1 and H7N9 infection, estimated the relative risk of infection in blood-related contacts, and the reproduction number (R).

Results: We assembled and analyzed data on 720 H5N1 cases and 460 H7N9 cases up to 2 November 2014. The severity and average age of sporadic/index cases of H7N9 was greater than secondary cases (71% requiring intensive care unit admission vs 33%, P = .007; median age 59 years vs 31, P < .001). We observed no significant differences in the age and severity between sporadic/index and secondary H5N1 cases. The upper limit of the 95% confidence interval (CI) for R was 0.12 for H5N1 and 0.27 for H7N9. A higher proportion of H5N1 infections occurred in clusters (20%) compared to H7N9 (8%). The relative risk of infection in blood-related contacts of cases compared to unrelated contacts was 8.96 for H5N1 (95% CI, 1.30, 61.86) and 0.80 for H7N9 (95% CI, .32, 1.97).

Conclusions: The results are consistent with an ascertainment bias towards severe and older cases for sporadic H7N9 but not for H5N1. The lack of evidence for ascertainment bias in sporadic H5N1 cases, the more pronounced clustering of cases, and the higher risk of infection in blood-related contacts, support the hypothesis that susceptibility to H5N1 may be limited and familial. This analysis suggests the potential pandemic risk may be greater for H7N9 than H5N1.
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http://dx.doi.org/10.1093/cid/civ345DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4542598PMC
August 2015

Thirty years of vaccination in Vietnam: Impact and cost-effectiveness of the national Expanded Programme on Immunization.

Vaccine 2015 May;33 Suppl 1:A233-9

National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.

Introduction: 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.

Methods: 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.

Results: 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.

Conclusion: 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.
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http://dx.doi.org/10.1016/j.vaccine.2014.12.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4428532PMC
May 2015

A cluster randomised trial of cloth masks compared with medical masks in healthcare workers.

BMJ Open 2015 Apr 22;5(4):e006577. Epub 2015 Apr 22.

Beijing Centers for Disease Control and Prevention, Beijing, China.

Objective: The aim of this study was to compare the efficacy of cloth masks to medical masks in hospital healthcare workers (HCWs). The null hypothesis is that there is no difference between medical masks and cloth masks.

Setting: 14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam.

Participants: 1607 hospital HCWs aged ≥18 years working full-time in selected high-risk wards.

Intervention: Hospital wards were randomised to: medical masks, cloth masks or a control group (usual practice, which included mask wearing). Participants used the mask on every shift for 4 consecutive weeks.

Main Outcome Measure: Clinical respiratory illness (CRI), influenza-like illness (ILI) and laboratory-confirmed respiratory virus infection.

Results: The rates of all infection outcomes were highest in the cloth mask arm, with the rate of ILI statistically significantly higher in the cloth mask arm (relative risk (RR)=13.00, 95% CI 1.69 to 100.07) compared with the medical mask arm. Cloth masks also had significantly higher rates of ILI compared with the control arm. An analysis by mask use showed ILI (RR=6.64, 95% CI 1.45 to 28.65) and laboratory-confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were significantly higher in the cloth masks group compared with the medical masks group. Penetration of cloth masks by particles was almost 97% and medical masks 44%.

Conclusions: This study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated.

Trial Registration Number: Australian New Zealand Clinical Trials Registry: ACTRN12610000887077.
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http://dx.doi.org/10.1136/bmjopen-2014-006577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971PMC
April 2015

Examining the policies and guidelines around the use of masks and respirators by healthcare workers in China, Pakistan and Vietnam.

J Infect Prev 2015 Mar 10;16(2):68-74. Epub 2014 Dec 10.

School of Public Health and Community Medicine, UNSW Medicine, University of New South Wales, Australia.

Background: There is an ongoing debate regarding the type of respiratory protection that should be recommended for use for healthcare workers.

Materials And Methods: A cross-sectional survey was conducted in three countries: China, Pakistan and Vietnam.

Results: In China and Pakistan, the infection control guidelines were developed to be in line with the recommendations from the World Health Organization (WHO) and the Centers for Disease Control and Prevention, while in the Vietnamese guidelines the recommendations correspond with the WHO suggestions only. The guidelines from all three countries document the need for training and fit testing; however there is no system to monitor the training and fit testing programs. Across the three countries, there was some inconsistency with regard to the types of products (i.e. masks vs. respirators) recommended for influenza, severe acute respiratory syndrome (SARS) and tuberculosis.

Conclusions: Available evidence should be examined and a comprehensive policy should be developed on the use of masks and respirators. The policy should address critical areas such as regulation, training, fit testing and reuse.
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http://dx.doi.org/10.1177/1757177414560251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5074170PMC
March 2015

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