The Epidemiology and Control of Human Influenza in Vietnam

Understanding the epidemiology of human influenza in Viet Nam is important for developing local policies and also for understanding the dynamics of influenza in tropical and subtropical southeast Asia. I have analysed an 18 year time-series of influenza-like-illness (ILI) surveillance data, and assessed the relationship of this time-series with climate variables and with sentinel influenza virus surveillance data. I also conducted a study of influenza A/H1N1 transmission within households. ILI notifications in Viet Nam show a latitudinal gradient, with seasonality in the north but no seasonal pattern observed in low lying areas of central and southern Viet Nam. Seasonality is however observed in the elevated provinces of central Viet Nam, suggesting that the seasonal patterns are driven by climate. Principal component analysis finds that temperature and absolute humidity (AH) are positively correlated and together explain around 59% of total climatic variance, and that there is a strong latitudinal gradient in these variables. Regression tree analysis shows that provinces with strong seasonality of AH have strong ILI seasonality. Although virological surveillance data are limited, increases in ILI notifications are associated with an increase in the proportion of upper respiratory tract swabs that are influenza positive. In a prospective study of H1N1/2009 transmission in a household-based cohort, 11 of 59 household contacts were infected, giving a household secondary infection risk of 18.6% (95%CI 10.7-30.4%), but 5 (45%) did not develop symptoms. Virus genetic sequencing indicated that 10 of the 11 secondary cases (91%) were probably infected within the household rather than from the community. This research provides new insights into the seasonality and climatic determinants of ILI and influenza epidemiology in Viet Nam, and on the transmission of influenza within households. The findings are valuable for national influenza control policies and also add to the current state of knowledge of influenza epidemiology

Would greater household wealth make young children smarter?

Drawing on the Young Lives data obtained from three cycles of surveys from 2006 to 2016, our study examines factors affecting children’s cognitive ability in Vietnam. Controlling for the conditional wealth, which is the residual of the regression equation of the household wealth index in 2006 and 2013, our study provides evidence that conditional wealth has an effect of increasing the cognitive capacity of 15-year-old children, manifested in all three methods of measurement: by vocabulary points, math scores and reading comprehension scores in Vietnamese. This finding once again confirms that late intervention after the first 1,000 days has a positive impact on children's cognitive ability. Notably, our finding suggests that using the conditional wealth enables to capture the impact of economic shocks, which in turn have a significant effect on the cognitive ability of children in Vietnam

Observations on multiple mating flights of Apis dorsata queens

This observation is aimed at providing information for a reasonable comparative study on reproductive biology among the honeybee species. The research was carried out in 1996 in the submerged Melaleuca forest of southern Vietnam, where low-nesting colonies on man-made supports, rafters, allowed us to make detailed observations on the queens. Flights of six newly emerged queens were observed and after their final mating flights, queens were dissected to count the sperm number. The five investigated queens took their first flights 6 ± 1 (mean ± SD) days after emergence. Four queens took orientation flights of less than 3 min. One queen flew to mate without any orientation flight. Mating flights happened around sunset and lasted 15.4 ± 4.3 (n = 14) min. A queen undertook two to four mating flights and after fully mating, she had 5.5 ± 0.9 (n = 5) million sperm in her spermatheca. This study indicated the extreme polyandry in A. dorsata. © Inra/DIB/AGIB/Elsevier, Pari

Influenza vaccine allocation in tropical settings under constrained resources

Influenza virus seasonality, synchronicity, and vaccine supply differ substantially between temperate and tropical settings, and optimal vaccination strategy may differ on this basis. Many national vaccine recommendations focus on high-risk groups, elderly populations, and healthcare workers despite previous analyses demonstrating broad benefits to vaccinating younger high-contact age groups. In this study, we parameterized an age-structured nonseasonal asynchronous epidemiological model of influenza virus transmission for a tropical low-income setting. We evaluated timing and age allocation of vaccines across vaccine supplies ranging from 10 to 90% using decade-based age groups. Year-round vaccination was beneficial when compared with more concentrated annual vaccine distribution. When targeting a single age group for vaccine prioritization, maximum vaccine allocation to the 10–19 high-contact age group minimized annual influenza mortality for all but one vaccine supply. When evaluating across all possible age allocations, optimal strategies always allocated a plurality of vaccines to school-age children (10–19). The converse, however, was not true as not all strategies allocating a plurality to children aged 10–19 minimized mortality. Allocating a high proportion of vaccine supply to the 10–19 age group is necessary but not sufficient to minimize annual mortality as distribution of remaining vaccine doses to other age groups also needs to be optimized. Strategies focusing on indirect benefits (vaccinating children) showed higher variance in mortality outcomes than strategies focusing on direct benefits (vaccinating the elderly). However, the indirect benefit approaches showed a lower mean mortality and a lower minimum mortality than vaccination focused on the elderly

Hospital-acquired infections and unvaccinated children due to chronic diseases: an investigation of the 2017–2019 measles outbreak in the northern region of Vietnam

Background: Measles remains a major public health burden worldwide. Parents often hesitate to vaccinate children with chronic diseases. We investigated the association between the percentage of vaccination and chronic diseases and explore hospital infections’ role in the 2017–2019 measles outbreak across northern Vietnam provinces. Methods: A total of 2,064 children aged 0–15 years old admitted for measles to the National Children’s Hospital during the outbreak were included in the study. Demographic information, clinical characteristics, vaccination statuses and laboratory examination were extracted from electronic medical records, vaccination records, or interviews with parents when other sources were unavailable. Results: The incidence rate that provincial hospitals sent to the National Children’s Hospital was proportional to the population density of their provinces of residence. Early nosocomial transmission of measles was observed before community-acquired cases emerged in many provinces. Among patients aged over 18 months, those with chronic diseases had a proportion of vaccination of 9.4%, lower than patients without chronic diseases at 32.4%. Unvaccinated patients had a higher proportion of hospital-acquired infections with aOR = 2.42 (1.65–3.65), p < 0.001 relative to vaccinated patients. The proportion of hospital-acquired infections was higher among children with chronic diseases compared to those without, with aOR = 3.81 (2.90–5.02), p < 0.001. Conclusion: Measles spread in healthcare settings prior to community cases that occurred in several provinces. We recommend enhancing hospital infection control by increasing staff training and improving early detection and isolation during non-outbreak periods. Measles patients with chronic diseases exhibited lower proportions of vaccination and faced a higher risk of hospital-acquired infections. It is crucial to establish comprehensive vaccination guidelines and enhance parental awareness regarding the significance and safety of measles vaccination to protect these vulnerable individuals

Constrained Twin Variational Auto-Encoder for Intrusion Detection in IoT Systems

Intrusion detection systems (IDSs) play a critical role in protecting billions of IoT devices from malicious attacks. However, the IDSs for IoT devices face inherent challenges of IoT systems, including the heterogeneity of IoT data/devices, the high dimensionality of training data, and the imbalanced data. Moreover, the deployment of IDSs on IoT systems is challenging, and sometimes impossible, due to the limited resources such as memory/storage and computing capability of typical IoT devices. To tackle these challenges, this article proposes a novel deep neural network/architecture called Constrained Twin Variational Auto-Encoder (CTVAE) that can feed classifiers of IDSs with more separable/distinguishable and lower-dimensional representation data. Additionally, in comparison to the state-of-the-art neural networks used in IDSs, CTVAE requires less memory/storage and computing power, hence making it more suitable for IoT IDS systems. Extensive experiments with the 11 most popular IoT botnet datasets show that CTVAE can boost around 1% in terms of accuracy and Fscore in detection attack compared to the state-of-the-art machine learning and representation learning methods, whilst the running time for attack detection is lower than 2E-6 seconds and the model size is lower than 1 MB. We also further investigate various characteristics of CTVAE in the latent space and in the reconstruction representation to demonstrate its efficacy compared with current well-known methods