Objective: The risk of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from schoolchildren to their household and the protective effects of vaccination in these settings remain poorly understood. We assessed the transmission dynamics of schoolchildren with SARS-CoV-2 within their households and the protective effects of coronavirus disease (COVID-19) vaccination among household members in Viet Nam. Methods: We estimated the attack rate, vaccine effectiveness and adjusted risk ratio (aRR) of factors associated with SARS-CoV-2 transmission to household contacts of children confirmed to have COVID-19 who attended three schools in Ha Nam, Phu Tho and Thanh Hoa provinces between September and December 2021 using multivariable regression with household-level random effects. Results: This retrospective cohort study included 157 children infected with SARS-CoV-2 and their 540 household contacts. The attack rate among household contacts was 24.6% (133/540). Overall, vaccine effectiveness among household contacts was 39% (95% confidence interval [CI]: -1 to -63), higher among males than females and higher in adults aged >40 years. COVID-19 transmission was greater among female household contacts compared with males (aRR: 1.35, 95% CI: 0.94 to 1.95), although not statistically significant, and highest among those aged 19–39 years (aRR: 2.51, 95% CI: 1.50 to 4.21). Fully vaccinated household contacts had significantly lower infection risk (aRR: 0.46, 95% CI: 0.26 to 0.84). Discussion: We found substantial onward transmission of SARS-CoV-2 from schoolchildren to household members, and older people were more likely to be protected by vaccination. We recommend that schoolchildren and all household members living with schoolchildren receive at least two doses of a COVID-19 vaccine. Recognizing the role of schoolchildren in the onward transmission of COVID-19 is an important lesson learned by Viet Nam that can help not only in managing other outbreaks but also in protecting schoolchildren by predicting the progress of the outbreak and preparing for a timely response.

Objectives: Asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and test re-positivity after a negative test have raised concerns about the ability to effectively control the coronavirus disease 2019 (COVID-19) pandemic. We aimed to investigate the prevalence of COVID-19 asymptomatic and pre-symptomatic infections during the second wave of COVID-19 in Viet Nam, and to better understand the duration of SARS-CoV-2 infection and the dynamics between the evolution of clinical symptoms and SARS-CoV-2 test positivity among confirmed COVID-19 cases. Methods: We conducted a cohort analysis on the first 50 confirmed cases during the second COVID-19 wave in Viet Nam using clinical, laboratory and epidemiological data collected from 9 March to 30 April 2020. Kaplan-Meier estimates were used to assess time to clearance of SARS-CoV-2 infection, and log-rank tests were used to explore factors related to time to SARS-CoV-2 infection clearance. Results: Most cases (58%) had no typical signs or symptoms of COVID-19 at the time of diagnosis. Ten cases (20%) were re-positive for SARS-CoV-2 during infection. Eight cases (16%) experienced COVID-19 symptoms after testing negative for SARS-CoV-2. The median duration from symptom onset until clearance of infection was 14 days (range: 6–31); it was longer in re-positive and older patients and those with pre-existing conditions. Conclusion Asymptomatic and pre-symptomatic infections were common during the second wave of COVID-19 in Viet Nam. Re-positivity was frequent during hospitalization and led to a long duration of SARS-CoV-2 infection.

BACKGROUND: In order to provide essential scientific evidence on the population's health status and social health determinants as well as the current capacity of the health care system in Vietnam to health policy makers and managers, Vietnam Ministry of Health, Hanoi University of Public Health, Hanoi Medical University, and Ho Chi Minh University of Medicine and Pharmacy collaborated with Seoul National University (Korea) and conducted a health system survey in the Quoc Oai district (of Hanoi capital) that represented northern rural Vietnam. METHODS: The study design was a cross-sectional study. The survey covered different topics (more than 200 questions) and was administered in three separate questionnaires: 1) Basic information of all household members; 2) Household characteristics; and 3) Individual characteristics. Socio-demographic characteristics among the households and individuals were collected from 2,400 households sampled by multi-stage cluster sampling method: more than 200 questions. RESULTS: The household size of Quoc Oai was larger than the national average and there was no significant difference in gender composition. In addition, the proportions of pre-elderly, age 55–64, and elderly group (65 years old and over) were higher than the national population statistics. In this context, demographic transition has begun in Quoc Oai. CONCLUSION: This study design description provides the basic information about a baseline survey of a future prospective cohort (as a part of a collaborative project on strengthening the health system in Vietnam) to the prospective data user of this survey.
Aged ; Cohort Studies ; Cross-Sectional Studies ; Delivery of Health Care ; Family Characteristics ; Health Policy ; Humans ; Methods ; Pharmacy ; Population Characteristics ; Population Dynamics ; Prospective Studies ; Public Health ; Seoul ; Surveys and Questionnaires ; Vietnam

Study on chemical coposition of essential oil from Zanthoxylum nitidum fruit collected at Me Linh district, Vinh Phuc province by GC/MS method. Results: the yield of essential oil from fruit was 0.35% by air-dry material, 27 constituents were identified, in which the main constituents were linalool L. (72.17%) and sabinen (11.24%)
chemistry ; Oils, Volatile ; Zanthoxylum

The determination of the contents and chemical components essential oil of Sen hoi (Zanthixylum rhetsa Roxl DC) collected in Mai Chau, Hoa Binh provine in Feb 2003 showed that the essential oil content reached 9,6% of dry product and 24 compouds was identified, among then the main compounds are benzen derivatives, 1- methoxy-4 (1- propenyl), benzaldehyd-4-methoxy, 1-butanon, 1- (4- hydroxy phemyl) and benzen-e,ethanol, alpha-ethyl-4-4 methoxy
Chemistry ; Oils, volatile ; Zanthoxylum

The qualitative and quantitative analyses of Atalantia roxburghiana Hook. f. essential oil, using gas chromatography – mass spectrum method, were described. The essential oil content calculated on air dried leaves and fruits was 0.09%. The main constituents among 30 compounds identified in the oil were: para-cymene (13.37%), gamma-terpinene (40.63%), limonene (4.58%), and beta-pinene (4.59%).
Chemistry ; Plants ; Plants, Medicinal ; oils

Limnophyla rugosa is an erect-semi aquatic, fragrant, annual herb, up to 50 cm tall. Stem simple or branch, glabrous to hirsute, rooting from the lower nodes, leaves decussate, ovate-lanceolate to oval elliptical 2-8cmx1-5 cm, flowers solitary in axillary; sometimes in axillary pendunculate clusters with up to 7 sessile. Limnophyla rogusa occurs in moist along treams,pools and rice field from sea-level up to 1500 m attitude. Yield of essential oil from aerial parts of Limnophyla rogusa was 0.18 percent by air-dry material, 23 constituents of the essential oil were identified by GC/MS. Major constituent of essential oil was anethol (89.4%)
Oils, Volatile ; oils ; Chemistry ; Plants ; Medicine, Traditional

Desmos chinensis is a climber tree. Branches brown pubescent, leaves glaucous underneath, petals yellow. This tree distributes in many provinces of Viet Nam, mostly in Yen Bai, Ha Giang, Thai Nguyen, Bac Giang, Vinh Phuc, Quang Ninh, Hoa Binh, Ninh Binh, Quang Binh, Ha Tinh, Thua Thien Hue, Kontum, Dong Nai. The oil yield was 0.2% from air-dried flowers. The essential oil of Desmos chinensis was analysed using GS and RMN. 13 constituents have been identified, including beta-caryophyllene (28.9%), bicyclogermacren (11.5%), alpha-humullene (7.2%), D-germacren (7.2%), beta-elemene (6.4%)
chemistry ; Flowers ; Oils ; Oils, Volatile

Schefflera aff. crassibracteata is a shrub 6 high, leaflets 6-12. It is distributed in HoaBinh, NinhBinh, PhuKhanh provinces. The oil yield from leaves was 0.24% by air-dry material. The essential oil was analysed by HRGC and GC/MS, 61 constituents have been identified. Major components were: caryophyllen oxide (12.1%); -pinene (8.9%); -pinen (4.8%) and T-muurolol (4.7%).
Chemistry ; Oils, Volatile

Glycosmis pentaphylla is a shrub 4-5m high, leaflets 2-5, white flower, fruit around. It is distributed in edge of forest in North midland area of Vietnam. The oil yield was 0.3% from branch with leaves and flower by air-dry material. The essential oil of Glycosmis pentaphylla was analyzed by GC/MS, 88 constituents have been identified. Major constituents were: alpha-pipene (27.1%); beta-caryophyllene (10.3%); spathulenol (7.7%); caryophyllen oxid (7.3%) and aromadendren 6.4%.
Chemicals and Ingredients ; oils ; Plants, Medicinal ; Medicine, Traditional