OBJECTIVES:Dengue fever remains a critical public health challenge worldwide, especially in endemic regions such as Vietnam, where rapid urbanization and climate change exacerbate transmission. Despite frequent outbreaks, the spatiotemporal epidemiology of dengue in Vietnam is poorly characterized. This study aimed to elucidate the epidemic dynamics to inform targeted intervention strategies. METHODS:We analyzed national case and mortality data from 1998 to 2020, employing advanced geospatial analysis tools (R and SatScan) to identify high-risk areas and transmission patterns. RESULTS:Over 23 years, the case fatality rate was consistently low (0.1-0.2%), despite discrepancies between reported dengue virus strains and clinical cases. Key high-risk zones included the Mekong Delta, southern metropolitan areas, south-central Vietnam, and Hanoi, with distinct temporal peaks, primarily between June and November. Notably, southern Vietnam experienced persistent simultaneous outbreaks, whereas the epidemic activity in Hanoi was more localized. CONCLUSIONS:Our findings delineate the critical zones and seasons of dengue transmission in Vietnam, providing essential evidence for optimizing resource allocation and surveillance efforts. These insights are vital for developing preemptive public health interventions in resource-constrained endemic settings.
Coxsackievirus A10 (CV-A10) has become an important cause of hand, foot, and mouth disease (HFMD). Molecular surveillance in northern Vietnam during 2018–2020 revealed the introduction and rapid dominance of the genotype C lineage (CHN), replacing the previously endemic lineage (VNM). This shift was associated with a significant increase in detection and altered clinical severity, predominantly grade 2A (83.8
We previously reported alarmingly high carriage rates of Streptococcus pneumoniae (SP) serotype 19F and serogroup 6 isolates, which were not susceptible to multiple beta-lactams among children under five years of age in Vietnam. Multilocus sequence typing analysis revealed the predominance of two major lineages, ST320 and ST13223, among serotype 19F and serogroup 6 isolates, respectively. Investigating the association between nonsusceptible genotypes and clinical outcomes could help optimize patient care or lead to the development of new diagnostic tests. We performed WGS on SP isolates randomly selected from the two major lineages and their related strains. FASTQ quality control and de novo assembly were performed using CLC Genomics Workbench ver. 7.5.1. Draft genome sequences were annotated using DFAST (DDBJ Fast Annotation and Submission Tool), which revealed the serogroups/serotypes and the sequences of the three major penicillin-binding protein genes and the sequence types. Draft sequences were aligned using MUMmer ver. 3.23, and putative recombination events and phylogenetic relationships excluding recombination regions were identified using Gubbins ver. 2.4.1. Finally, the association between a detected nonsusceptible genotype and the duration of hospital stay was evaluated in patients with acute respiratory infection. WGS analysis (serotype 19F/ST320, n = 22; serogroup 6/ST13223, n = 13; and isolates closely related to ST13223, n = 4) revealed substantial differences in genomic diversity and antimicrobial susceptibility between serogroup 6/ST13223 and serotype 19F/ST320 isolates, particularly the recombination-prone nature of serogroup 6/ST13223. Among the 23 recombination events observed in serogroup 6/ST13223, only those spanning the pbp2x region (15.5 kb and 6.4 kb) were associated with high MICs for multiple beta-lactams. A subset of ST13223 isolates and all ST320 isolates carried the identical pbp2x allele 16, which was significantly associated with a lack of susceptibility to the combination of penicillin, cefotaxime, and meropenem (p < 0.0001; odds ratio 11.5; 95
OBJECTIVES:To estimate the seroprevalence of anti-DENV antibodies in Vietnam, examining regional variability, demographic differences, and serotype distribution. STUDY DESIGN:Systematic review and meta-analysis. METHODS:We systematically searched PubMed, Embase, and Web of Science databases for studies published from January 2000 to June 2024. Eligible studies included observational studies reporting laboratory-confirmed dengue infections via serological assays (IgG, IgM) or molecular methods (RT-PCR). We utilized random-effects models to estimate pooled seroprevalence and assessed heterogeneity through the Inconsistency Index (I2). Publication bias was evaluated using funnel plots and Egger's test. RESULTS:Thirty-four studies involving 28,477 individuals were included. The overall pooled seroprevalence of dengue in Vietnam was 40.98% (95% CI: 30.52-51.43%), with substantial heterogeneity across study populations, geographic regions, and diagnostic methods, demonstrating regional variability ranging from 3.05% to 88.8%. This wide range likely reflects differences in study settings, including community-based populations, outbreak investigations, and clinically selected groups. Seroprevalence was higher among children aged 0-16 years (45.52%, 95% CI: 22.32-68.72%), which may partly reflect studies conducted in high-transmission or outbreak settings. Studies conducted among clinically suspected dengue cases showed seroprevalence of 30.57% (95% CI: 18.00-43.15%), although these estimates may be influenced by selection bias because participants were recruited based on clinical suspicion rather than from the general population. Secondary dengue infections were prevalent, ranging broadly between 26 and 75%. DENV-1 and DENV-2 serotypes were dominant, with DENV-2 becoming more frequent since 2021. CONCLUSIONS:This study underscores dengue's endemic nature in Vietnam, highlighting significant heterogeneity in seroprevalence related to geographical and demographic factors. The high prevalence of secondary infections and the predominance of DENV-1 and DENV-2 serotypes emphasize the need for targeted public health strategies, enhanced surveillance, and optimized vaccination programs tailored to regional and age-specific risk profiles.
BACKGROUND:Seasonal influenza causes significant morbidity among the elderly, yet vaccination remains an out-of-pocket expense in Vietnam. This study evaluated the willingness to pay (WTP) for influenza vaccination and its determinants among the elderly in Vietnam. METHODS:A community-based cross-sectional study was conducted in Can Tho City, Vietnam (N = 1486). We employed the Contingent Valuation Method with a Triple-Bounded Dichotomous Choice framework. Data were analyzed using multivariable logistic regression to identify predictors of WTP and interval regression to estimate the mean WTP and its monetary determinants. RESULTS:Overall, 54.9% of participants expressed a WTP, but only 28.9% were willing to cover the full market cost. The estimated mean WTP was 12.08 USD (95% CI: 11.66-12.50). Logistic regression revealed that vaccine hesitancy was the strongest predictor; non-hesitant individuals were 13.71 times more likely to express WTP (p < 0.001). Other significant predictors included high income (aOR = 2.22), medical recommendations (aOR = 1.80),and diabetes mellitus (aOR = 1.41). Interval regression showed that vaccine hesitancy "devalued" the vaccine by approximately 30%, with highly hesitant individuals willing to pay 4.12 USD less than those with low hesitancy. Conversely, media exposure increased the WTP amount by 1.10 USD. Most respondents (66.1%) identified the state budget as the preferred financial support source. CONCLUSIONS:A significant affordability gap exists for influenza vaccination among the Vietnamese elderly. While financial subsidies are necessary to support low-income groups, they must be paired with communication strategies to reduce vaccine hesitancy. We recommend a subsidized co-payment model (minimum 4-5 USD subsidy per dose) and leveraging healthcare provider recommendations to enhance vaccine valuation and uptake.
