Antibodies to S2 domain of SARS-CoV-2 spike protein in Moderna mRNA vaccinated subjects sustain antibody-dependent NK cell-mediated cell cytotoxicity against Omicron BA.1.

Vaccination with the primary two-dose series of SARS-CoV-2 mRNA protects against infection with the ancestral strain, and limits the presentation of severe disease after re-infection by multiple variants of concern (VOC), including Omicron, despite the lack of a strong neutralizing response to these variants. We compared antibody responses in serum samples collected from mRNA-1273 (Moderna) vaccinated subjects to identify mechanisms of immune escape and cross-protection. Using pseudovirus constructs containing domain-specific amino acid changes representative of Omicron BA.1, combined with domain competition and RBD-antibody depletion, we showed that RBD antibodies were primarily responsible for virus neutralization and variant escape. Antibodies to NTD played a less significant role in antibody neutralization but acted along with RBD to enhance neutralization. S2 of Omicron BA.1 had no impact on neutralization escape, suggesting it is a less critical domain for antibody neutralization; however, it was as capable as S1 at eliciting IgG3 responses and NK-cell mediated, antibody-dependent cell cytotoxicity (ADCC). Antibody neutralization and ADCC activities to RBD, NTD, and S1 were all prone to BA.1 escape. In contrast, ADCC activities to S2 resisted BA.1 escape. In conclusion, S2 antibodies showed potent ADCC function and resisted Omicron BA.1 escape, suggesting that S2 contributes to cross-protection against Omicron BA.1. In line with its conserved nature, S2 may hold promise as a vaccine target against future variants of SARS-CoV-2.

Antibody Responses to the SARS-CoV-2 Ancestral Strain and Omicron Variants in Moderna mRNA-1273 Vaccinated Active-Duty US Navy Sailors and Marines.

Omicron and its subvariants have steadily gained greater capability of immune escape compared to other variants of concern, resulting in an increased incidence of reinfections even among vaccinated individuals. We evaluated the antibody response to Omicron BA.1, BA.2, and BA.4/5 in US military members vaccinated with the primary 2-dose series of Moderna mRNA-1273 in a cross-sectional study. While nearly all vaccinated participants had sustained spike (S) IgG and neutralizing antibodies (ND50) to the ancestral strain, only 7.7% participants had detectable ND50 to Omicron BA.1 at 8 months postvaccination. The neutralizing antibody response to BA.2 and BA.5 was similarly reduced. The reduced antibody neutralization of Omicron correlated with the decreased antibody binding to the receptor-binding domain. The participants' seropositivity to the nuclear protein positively correlated with ND50. Our data emphasizes the need for continuous vigilance in monitoring for emerging variants and the need to identify potential alternative targets for vaccine design.

Surveillance of pfhrp2 and pfhrp3 gene deletions among symptomatic Plasmodium falciparum malaria patients in Central Vietnam.

BACKGROUND: Malaria rapid diagnostic tests (RDTs) remain the main point-of-care tests for diagnosis of symptomatic Plasmodium falciparum malaria in endemic areas. However, parasites with gene deletions in the most common RDT target, histidine rich protein 2 (pfhrp2/HRP2), can produce false-negative RDT results leading to inadequate case management. The objective of this study was to determine the prevalence of hrp2/3 deletions causing false-negative RDT results in Vietnam (Gia Lai and Dak Lak provinces). METHODS: Individuals presenting with malaria symptoms at health facilities were screened for P. falciparum infection using light microscopy and HRP2-RDT (SD Bioline Malaria Antigen Pf/Pv RDT, Abbott). Microscopically confirmed P. falciparum infections were analysed for parasite species by 18S rRNA qPCR, and pfhrp2 and pfhrp3 exon2 deletions were investigated by nested PCR. pfhrp2 amplicons were sequenced by the Sanger method and HRP2 plasma levels were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: The prevalence of false-negative RDT results among symptomatic cases was 5.6% (15/270). No pfhrp2 and pfhrp3 deletions were identified. False-negative RDT results were associated with lower parasite density (p = 0.005) and lower HRP2 plasma concentrations (p < 0.001), as compared to positive RDT. CONCLUSIONS: The absence of hrp2/3 deletions detected in this survey suggests that HRP2-based malaria RDTs remain effective for the diagnosis of symptomatic P. falciparum malaria in Central Vietnam.

Cross-sectional study of asymptomatic malaria and seroepidemiological surveillance of seven districts in Gia Lai province, Vietnam.

BACKGROUND: Malaria elimination by 2030 is an aim of many countries in the Greater Mekong Sub-region, including Vietnam. However, to achieve this goal and accelerate towards malaria elimination, countries need to determine the extent and prevalence of asymptomatic malaria as a potential reservoir for malaria transmission and the intensity of malaria transmission. The purpose of this study was to determine the prevalence of asymptomatic malaria and seropositivity rate in several districts of Gia Lai province in the Central Highlands of Vietnam. METHODS: A cross-sectional survey of asymptomatic malaria and serological testing was conducted in 3283 people living at 14 communes across seven districts in Gia Lai province in December 2016 to January 2017. Finger prick capillary blood samples were tested for malaria using rapid diagnostic testing and polymerase chain reaction (PCR), as well as detecting antibodies against 3 Plasmodium falciparum and 4 Plasmodium vivax antigens by indirect enzyme-linked immunosorbent assay (ELISA). Age-seroprevalence curves were fitted using reverse catalytic models with maximum likelihood. RESULTS: The study population was predominantly male (65.9%, 2165/3283), adults (88.7%, 2911/3283) and of a minority ethnicity (72.2%, 2371/3283), with most participants being farmers and outdoor government workers (90.2%, 2960/3283). Using a small volume of blood (≈ 10 µL) the PCR assay revealed that 1.74% (57/3283) of the participants had asymptomatic malaria (P. falciparum 1.07%, P. vivax 0.40%, Plasmodium malariae 0.15% and mixed infections 0.12%). In contrast, the annual malaria prevalence rates for clinical malaria in the communities where the participants lived were 0.12% (108/90,395) in 2016 and 0.22% (201/93,184) in 2017. Seropositivity for at least one P. falciparum or one P. vivax antigen was 38.5% (1257/3262) and 31.1% (1022/3282), respectively. Age-dependent trends in the proportion of seropositive individuals in five of the districts discriminated the three districts with sustained low malaria prevalence from the two districts with higher transmission. CONCLUSIONS: Asymptomatic Plasmodium carriers were found to be substantially more prevalent than clinical cases in seven districts of Gia Lai province, and a third of the population had serological evidence of previous malaria exposure. The findings add knowledge on the extent of asymptomatic malaria and transmission for developing malaria elimination strategies for Vietnam.

Training need assessment for a master training program in Environmental Health program in Vietnam.

Vietnam is facing a shortage of skilled Environmental health workforce. A Training Needs Assessment was conducted to develop a list of environmental health tasks, a list of core competencies and assess the need for a Master of Environmental Health training program in Vietnam. To answer these questions, a cross-sectional study was conducted in Vietnam in 2017, using both qualitative and quantitative methods. The qualitative study involved a desk review, 29 in-depth interviews, two consultative workshops, and two expert meetings. For the quantitative component, 298 environmental health staff working at different levels completed a structured postal questionnaire. Results showed that different sectors were implementing various environmental health tasks but that there was currently no training program focusing on environmental health in Vietnam. Thirteen core competencies for a Master of Environmental Health were recommended. An urgent need to develop training programs to help building environmental health competencies at the Masters degree level was uniformly expressed. This could be achieved by developing a Master of Public Health with an Environmental Health stream in the short-term and a Master of Environmental Health program in the long-term.

Community-based father education intervention on breastfeeding practice-Results of a quasi-experimental study.

Although the benefits of breastfeeding are well-documented, little is known about how best to encourage fathers to support breastfeeding. A quasi-experimental study of a community-based intervention was designed to examine whether health education to promote fathers' involvement in supporting women is associated with early initiation and exclusive breastfeeding practices. At baseline, 802 couples of fathers with pregnant wives from 12 to 27 weeks of gestational age were recruited to either the intervention group (n = 390) or a control group (n = 412) consisting of couples seeking care through routine maternal and child health services. Fathers in the intervention area received breastfeeding education and counselling services in health facilities and at home visits during the antenatal, delivery, and post-partum periods. Peer education and social exchange concerning breastfeeding were organized in fathers' clubs. After 1 year of the intervention, mothers in the intervention group were more likely to initiate early breastfeeding 49.2 and 35.8% in the intervention and control group respectively, P < 0.001. At 1, 4, and 6 months after birth, 34.8, 18.7, and 1.9% of the mothers in the intervention group were exclusively breastfeeding their children because of birth, respectively, compared with 5.7, 4.0, and 0.0% of those in the control group (P < 0.001). Those practices were associated with the intervention in bivariate and multivariate logistic and Cox regression analyses. Intervention targeting fathers at antenatal and postnatal periods may positively influence the breastfeeding practices of mothers, and it should be an important component of breastfeeding programs.

Water Supply, Sanitation, and Medical Waste Treatment and Disposal at Commune Health Centers in Vietnam.

Water hygiene, sanitation, and proper management of health care wastes at health care facilities are important in preventing infections and improving health and the environment. This article describes the access to safe water and sanitation facilities and the disposal of medical wastes at commune health centers (CHCs) in Vietnam. Data was extracted from the 2015 World Bank Vietnam District and Commune Health Facility Survey. Bivariate and multivariate logistic regression was applied to identify associations of CHCs' access to improved water and sanitation and their medical waste management. Overall, 72.76% CHCs had access to both improved water and sanitation facilities, and better access was found in the richest communes. Rural CHCs had higher prevalence of appropriate wastewater treatment. The majority of CHCs combusted medical solid wastes by specialized incinerations, contracted out with sanitation companies, or transported them to district health centers. However, the data was insufficient to give in-depth analysis and conclusion on water and sanitation conditions and the management of medical wastes at CHCs. More information should be collected for further analysis and conclusion.

Exposure to Tobacco Advertising, Promotion Among the Adult Population in Vietnam and Its Implications for Public Health.

INTRODUCTION: The Law on Tobacco Control and the Law on Advertisement prohibit the advertising of any tobacco product in Vietnam. Tobacco promotion and marketing are alsostrictly prohibited. However, the violation of tobacco adverting and promotion is still common in Vietnam. OBJECTIVES: This article aims at describing the exposure to tobacco advertising and promotion among the population aged 15+ years in Vietnam based on the data from the Global Adult Tobacco Survey 2015 from the view of the community, identifying any possible associations between the exposure to tobacco advertising and promotion and other individual factors, and discussing its possible public health implications. METHOD: A cross-sectional study with the nationwide scale. Secondary data from the Global Adult Tobacco Survey 2015 was explored and analyzed. Chi-square test and multivariate logistic regressions were applied in the data analysis. RESULTS: The most common type of adults' exposure to tobacco advertising and promotion was points of sale (8.6%); 9.8% adults exposure to one source of tobacco advertising and 4.0% of them exposed to one source of tobacco promotion. Around 13.3% of Vietnamese adults were exposed to tobacco advertisement, while 2.0% were exposed to tobacco promotion, 5.3% were exposed to both tobacco advertising and promotion, and 16.6% were exposed to tobacco advertising or promotion. Gender, educational level, age, occupation, marital status, socioeconomic status, location (urban, rural), and current smoking status were associated with the exposure to tobacco advertising, tobacco promotion, tobacco advertising and promotion, and tobacco advertising or promotion. CONCLUSION AND RECOMMENDATION: Although there are comprehensive bans on tobacco advertising and promotion in Vietnam, adults aged 15+ years still reported their exposure to tobacco advertising and promotion. There should be a strict enforcement of the ban on tobacco advertising and promotion in Vietnam.

Exposure to Tobacco Advertising and Promotion among School Children Aged 13-15 in Vietnam - an Overview from GYTS 2014.

Evidence shows that tobacco advertising and promotion activities may increase tobacco consumption and usage, especially in youth. Despite the regulation on prohibiting advertisement of any tobacco product, tobacco advertisement and promotion activities are still common in Vietnam. This article presents current exposure to tobacco advertising and promotion (TAP) among school children aged 13 to 15 years in Vietnam in 2014 and potential influencing factors. Data from the Global Youth Tobacco Survey 2014 in Vietnam covering 3,430 school aged children were used. Both descriptive and analytical statistics were carried out with Stata 13 statistical software. Binary logistic regression was applied to explain the exposure to TAP among youth and examine relationships with individual factors. A significance level of p<0.05 and sampling weights were used in all of the computations. In the past 30 days, 48.6% of the students experienced exposure to at least 1 type of tobacco advertising or promotion. Wearing or otherwise using products related to tobacco was the most exposure TAP type reported by students (22.3%). The internet (22.1), points of sales (19.2) and social events (11.5) were three places that students aged 13-15 frequently were exposed to TAP. Binary logistic results showed that gender (female vs male) (OR = 0.61, 95%CI: 0.52 - 0.71), susceptibility to smoking (OR = 2.12, 95%CI: 1.53 - 2.92), closest friends' smoked (OR = 1.43, 95%CI: 1.2 - 1.7) and parents smoking status (OR = 2.83, 95%CI: 1.6 - 5.01) were significantly associated with TAP exposure among school-aged children. The research findings should contribute to effective implementation of measures for preventing and controlling tobacco use among students aged 13-15 in Viet Nam.

Violation of Bans on Tobacco Advertising and Promotion at Points of Sale in Viet Nam: Trend from 2009 - 2015.

Comprehensive bans on tobacco advertising and promotion were introduced through tobacco control legislation in Viet Nam, but it has been established that violations of the bans are very common. This study was conducted to explore the trend in violations of bans on tobacco advertising and promotion at points of sale in Viet Nam in the past six years and to explore any differences in the violation situations before and after the Law on Tobacco Control came into effect on 1st May 2013. Quantitative data were collected through observation of violations of the bans on tobacco advertising and promotion at points of sale in 10 provinces throughout Viet Nam in four survey rounds (2009, 2010, 2011, and 2015). Variation in violation prevalence over time was examined by chi-square test using a Bonferini method. Binary logistic regression was employed to identify the factors that may have influences on different types of violation. A level of significance of p<0.05 was used for all tests in this article. The most common form of violation was the display of more than one pack/one carton of a cigarette brand. Violation of bans on tobacco advertising increased while violations on promotion ban and on displaying tobacco decreased through time. Some factors associated with the tobacco advertising and promotion bans included surveyed years, types of points of sale, regions and areas where the points of sale were located. The enforcement of the bans did not improve even after the issuance and the enactment of the Law on Tobacco Control. This suggests that the monitoring and enforcement of bans on tobacco advertising and promotion at points of sale should be strengthened. Penalties should be strictly applied for violators as indicated in the current tobacco control legislation.

Household trends in access to improved water sources and sanitation facilities in Vietnam and associated factors: findings from the Multiple Indicator Cluster Surveys, 2000-2011.

BACKGROUND: Despite progress made by the Millennium Development Goal (MDG) number 7.C, Vietnam still faces challenges with regard to the provision of access to safe drinking water and basic sanitation. OBJECTIVE: This paper describes household trends in access to improved water sources and sanitation facilities separately, and analyses factors associated with access to improved water sources and sanitation facilities in combination. DESIGN: Secondary data from the Vietnam Multiple Indicator Cluster Survey in 2000, 2006, and 2011 were analyzed. Descriptive statistics and tests of significance describe trends over time in access to water and sanitation by location, demographic and socio-economic factors. Binary logistic regressions (2000, 2006, and 2011) describe associations between access to water and sanitation, and geographic, demographic, and socio-economic factors. RESULTS: There have been some outstanding developments in access to improved water sources and sanitation facilities from 2000 to 2011. In 2011, the proportion of households with access to improved water sources and sanitation facilities reached 90% and 77%, respectively, meeting the 2015 MDG targets for safe drinking water and basic sanitation set at 88% and 75%, respectively. However, despite these achievements, in 2011, only 74% of households overall had access to combined improved drinking water and sanitation facilities. There were also stark differences between regions. In 2011, only 47% of households had access to both improved water and sanitation facilities in the Mekong River Delta compared with 94% in the Red River Delta. In 2011, households in urban compared to rural areas were more than twice as likely (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.9-2.5) to have access to improved water and sanitation facilities in combination, and households in the highest compared with the lowest wealth quintile were over 40 times more likely (OR: 42.3; 95% CI: 29.8-60.0). CONCLUSIONS: More efforts are required to increase household access to both improved water and sanitation facilities in the Mekong River Delta, South East and Central Highlands regions of Vietnam. There is also a need to address socio-economic factors associated with inadequate access to improved sanitation facilities.

Decreasing In-home Smoking of Adults-Results from a School-based Intervention Program in Viet Nam.

It is indicated that children are involuntarily exposed to secondhand smoke from adults, mainly at their home environment. This study aimed at describing the effectiveness of the school-based intervention to decrease the in-home smoking situation of adults so as to decrease children's exposure to secondhand smoke at home during the year 2011-2012 in a rural district in Hanoi, Viet Nam. This school-based intervention program (intervention and control group) involved 804 children aged 8 to 11 years from August 2011 to May 2012 in a rural district of Hanoi, Viet Nam. Children were taught in class about the harmful effects of secondhand smoke and about how to negotiate with fathers not to smoke in-home. Then children applied what they learnt, including staying away from secondhand smoke and persuading fathers not to smoke in-home in order to decrease children's exposure to secondhand smoke. Chi square test, t-test and multinominal logistic regression were applied in data analysis. The results showed that children's reported their father's in-home smoking decreased from 83.0% pre-intervention to 59.8% post-intervention (p < 0.001) in the intervention school while no change happened in the control school. The study found that the better changed smoking location of adult smokers as reported by children associated with the school who received intervention activities (adjusted OR = 2.04; 95% CI: 1.28-3.24). Poorer changed attitudes towards secondhand smoke of children associated with a lower percentage of better change in smoking location of their fathers/other adult smokers (aOR = 0.51, 95% CI: 0.28-0.96). Children's poorer changed knowledge towards secondhand smoke also associated with poorer changed smoking location of adult smokers (aOR = 2.88, 95% CI: 1.07-7.76). It is recommended by this study that similar school based intervention approaches should be applied in primary schools in Viet Nam to increase children's awareness on the adverse health effects of secondhand smoke and to help them to be able to avoid their exposure to secondhand smoke at their home environment.

Longitudinal Household Trends in Access to Improved Water Sources and Sanitation in Chi Linh Town, Hai Duong Province, Viet Nam and Associated Factors.

OBJECTIVE: This study aims to characterize household trends in access to improved water sources and sanitaton in Chi Linh Town, Hai Duong Province, Vietnam, and to identify factors affecting those trends. METHOD: Data were extracted from the Chi Linh Health and Demographic Surveillance System (CHILILAB HDSS) database from 2004-2014, which included household access to improved water sources, household access to improved sanitation, and household demographic data. Descriptive statistical analysis and multinominal logistic regression were used. The results showed that over a 10-year period (2004-2014), the proportion of households with access to improved water and improved sanitation increased by 3.7% and 28.3%, respectively. As such, the 2015 Millennium Development Goal targets for safe drinking water and basic sanitation were met. However, 13.5% of households still had unimproved water and sanitation. People who are retired, work in trade or services, or other occupations were 1.49, 1.97, and 1.34 times more likely to have access to improved water and sanitation facilities than farming households, respectively (p < 0.001). Households living in urban areas were 1.84 times more likely than those living in rural areas to have access to improved water sources and improved sanitation facilities (OR =1.84; 95% CI = 1.73-1.96). Non-poor households were 2.12 times more likely to have access to improved water sources and improved sanitation facilities compared to the poor group (OR = 2.12; 95% CI = 2.00-2.25). More efforts are required to increase household access to both improved water and sanitation in Chi Linh Town, focusing on the 13.5% of households currently without access. Similar to situations observed elsewhere in Vietnam and other low- and middle- income countries, there is a need to address socio-economic factors that are associated with inadequate access to improved water sources and sanitation facilities.

Estimation of Vietnam national burden of disease 2008.

Burden of disease has been used to assess population health status. This article presents the first estimations of burden of disease in Vietnam in 2008 using disability-adjusted life years (DALYs). DALYs were calculated using the Global Burden of Disease (GBD) methods. Incidence, prevalence of diseases, and causes of death was extracted from Vietnam data. Disability weights were borrowed from GBD and Dutch research. In 2008, the total burden of disease in Vietnam was 12.3 million DALYs. Noncommunicable diseases dominated the total burden of diseases in Vietnam, accounting for 71% of the total burden, and cardiovascular disease was the leading cause group of premature death. While pneumonia was an important cause of burden in Vietnamese children, stroke and depression were the main causes of disease burden among adults. The study provides a snapshot of Vietnamese health status and offers guidance for health policymaking in Vietnam.