Age-specific prevalence of IgG against measles/rubella and the impact of routine and supplementary immunization activities: A multistage random cluster sampling study with mathematical modelling.

BACKGROUND: Vietnam continues to have measles and rubella outbreaks following supplementary immunization activities (SIA) and routine immunization despite both having high reported coverage. To evaluate immunization activities, age-specific immunity against measles and rubella, and the number of averted Congenital Rubella Syndrome (CRS) cases, must be estimated. METHODS: Dried blood spots were collected from 2091 randomly selected individuals aged 1-39 years. Measles and rubella virus-specific immunoglobulin G (IgG) were measured by enzyme immunoassay. Results were considered positive at ≥120 mIU/mL for measles and ≥10 IU/mL for rubella. The number of CRS cases averted by immunization since 2014 were estimated using mathematical modelling. RESULTS: Overall IgG seroprevalence was 99.7% (95%CI: 99.2-99.9) for measles and 83.6% (95%CI: 79.3-87.1) for rubella. Rubella IgG seroprevalence was higher among age groups targeted in the SIA than in non-targeted young adults (95.4% [95%CI: 92.9-97.0] vs 72.4% [95%CI: 63.1-80.1]; P < 0.001). The estimated number of CRS cases averted in 2019 by immunization activities since 2014 ranged from 126 (95%CI: 0-460) to 883 (95%CI: 0-2271) depending on the assumed postvaccination reduction in the force of infection. CONCLUSIONS: The results suggest the SIA was effective, while young adults born before 1998 who remain unprotected for rubella require further vaccination.

Sero and Carriage Epidemiology of Pertussis in Urban and Rural Regions in Vietnam.

The underestimation of the pertussis burden prompted our study to investigate the prevalence of recent pertussis infection, its associated factors, and antibody titer changes in the same individuals in Vietnam. Two cross-sectional surveys were conducted in Nha Trang in 2017 and Quang Ngai in 2019, representing high- and low-vaccine-coverage areas, respectively. Serum anti-pertussis toxin immunoglobulin-G (anti-PT IgG) ≥ 62.5 IU/mL by ELISA indicated infection in the previous 12 months. In Nha Trang, the participants of the 2017 survey were followed up in 2019. Logistic regression was used to determine the odds ratios for the characteristics associated with anti-PT IgG ≥ 62.5. The age-stratified prevalence in patients aged >2 years ranged from 2.1% (age 26-35) to 9.6% (3-5) in Nha Trang (2017) and from 7.2% (age 26-35) to 11.4% (6-15) in Quang Ngai. The prevalence tended to be higher in Quang Ngai across all age groups. Cough, recent antibiotic use, and smoking in Nha Trang were positively associated with an anti-PT IgG of ≥62.5, and having been diagnosed with pertussis and persistent cough with paroxysms/whoop in Quang Ngai were positively associated with an anti-PT IgG of ≥62.5. No nasopharyngeal swabs were positive for Bordetella pertussis using real-time PCR. The geometric mean of the IgG titer ratio from 2019 to 2017 was 1.45 in the paired samples. This study emphasizes Bordetella pertussis circulation across all age groups in both low- and high-vaccine-coverage settings in Vietnam, underscoring the need for continuous and standardized surveillance for a comprehensive understanding of its epidemiology.

Comparison of waist circumference and waist-to-height ratio as predictors of clustering of cardiovascular risk factors among middle-aged people in rural Khanh Hoa, Vietnam.

OBJECTIVE: Given the population-level variation in stature, a universal cut-off for waist circumference (WC) may not be appropriate for some populations. We compared the performance of WC and waist-to-height ratio (WHtR) to detect the clustering of cardiovascular disease (CVD) risk factors in rural Vietnam. METHODS: We obtained data from a baseline survey of the Khanh Hoa Cardiovascular Study comprising 2942 middle-aged residents (40-60 years). We used areas under the receiver operating characteristics curve (AUROC), net reclassification index (NRI), and integrated discrimination improvement (IDI) to compare the performance of WC and WHtR in predicting CVD risk clustering (≥2 of the following risk factors: hypertension, diabetes, dyslipidemia, and elevated C-reactive protein). RESULTS: The optimal cut-off values for WC were 81.8 and 80.7 cm for men and women, respectively. Regarding the clustering of CVD risk factors, the AUROC (95% CI) of WC and WHtR were 0.707 (0.676 to 0.739) and 0.719 (0.689 to 0.749) in men, and 0.682 (0.654 to 0.709) and 0.690 (0.663 to 0.717) in women, respectively. Compared with WC, WHtR had a better NRI (0.229; 0.102-0.344) and IDI (0.012; 0.004-0.020) in men and a better NRI (0.154; 0.050-0.257) in women. CONCLUSIONS: The optimal WC cut-off for Vietnamese men was approximately 10 cm below the recommended Asian cut-off. WHtR might perform slightly better in predicting the clustering of CVD risk factors among the rural population in Vietnam.

Association of green tea consumption with prediabetes, diabetes and markers of glucose metabolism in rural Vietnam: a cross-sectional study.

The literature on green tea consumption and glucose metabolism has reported conflicting findings. This cross-sectional study examined the association of green tea consumption with abnormal glucose metabolism among 3000 rural residents aged 40-60 years in Khánh Hòa province in Vietnam. Multinomial logistic regression analysis was conducted to examine the association of green tea consumption (0, < 200, 200-< 400, 400-< 600 or ≥ 600 ml/d) with prediabetes and diabetes (based on the American Diabetes Association criteria). Linear regression analysis was performed to examine the association between green tea consumption and the log-transformed homeostatic model assessment of insulin resistance (HOMA-IR) (a marker of insulin resistance) and the log-transformed homeostatic model assessment of ß-cell function (HOMA-ß) (a marker of insulin secretion). The OR for prediabetes and diabetes among participants who consumed ≥ 600 ml/d v. those who did not consume green tea were 1·61 (95 % CI = 1·07, 2·42) and 2·04 (95 % CI = 1·07, 3·89), respectively. Higher green tea consumption was associated with a higher level of log-transformed HOMA-IR (Pfor trend = 0·04) but not with a lower level of log-transformed HOMA-ß (Pfor trend = 0·75). Higher green tea consumption was positively associated with the prevalence of prediabetes, diabetes and insulin resistance in rural Vietnam. The findings of this study indicated prompting the need for further research considering context in understanding the link between green tea consumption and glucose metabolism, especially in rural settings in low- and middle-income countries.

Sex differences in the association between socioeconomic status and untreated hypertension among residents with hypertension in rural Khánh Hòa, Vietnam: a post-hoc analysis.

BACKGROUND: Several studies have examined the association between socioeconomic status (SES) and the proportion of untreated hypertension, but have produced conflicting findings. In addition, no study has been conducted to determine sex differences in the association between SES and untreated hypertension. Thus, the aim of this study was to examine whether the associations between SES and the proportion of untreated hypertension differed by sex in Vietnam. METHODS: This study was conducted using the data of 1189 individuals (558 males and 631 females) who were judged to have hypertension during the baseline survey of a prospective cohort study of 3000 residents aged 40-60 years in the Khánh Hòa Province. A multilevel Poisson regression model with a robust variance estimator was used to examine whether sex and SES indicators (household income and educational attainment) interacted in relation to untreated hypertension. RESULTS: The proportion of untreated hypertension among individuals identified as hypertensive was 69.1%. We found significant interaction between sex and SES indicators in relation to untreated hypertension (education: p < 0.001; household income: p < 0.001). Specifically, the association between SES and untreated hypertension was inverse among males while it was rather positive among females. CONCLUSIONS: Our finding suggests that the role of SES in the proportion of untreated hypertension might differ by sex.

Different associations of occupational and leisure-time physical activity with the prevalence of hypertension among middle-aged community dwellers in rural Khánh Hòa, Vietnam.

BACKGROUND: In contrast to high-income countries where physical activity (PA), particularly leisure-time PA, has been shown to be protective against hypertension, few studies have been conducted in low- and middle-income countries. We examined the cross-sectional association between PA and hypertension prevalence among rural residents in Vietnam. METHODS: We used data collected in the baseline survey of a prospective cohort study, among 3000 people aged 40-60 years old residing in rural Khánh Hòa, Vietnam. Hypertension was defined as systolic blood pressure ≥ 140 mmHg, diastolic blood pressure ≥ 90 mmHg, or the use of antihypertensive medication. We assessed occupational PA and leisure-time PA using the Global Physical Activity Questionnaire. A robust Poisson regression model was used to investigate the associations, with adjustment for covariates. RESULTS: The prevalence of hypertension was 39.6%. After adjusting for socio-demographic and lifestyle-related variables, leisure-time PA was positively associated with hypertension prevalence (prevalence ratio [PR]: 1.03 per 10 MET-hour/week, 95% confidence interval [CI] 1.01-1.06). Occupational PA was inversely associated with hypertension prevalence (PR: 0.98 per 50 MET-hour/week, 95% CI = 0.96-0.996). After adjusting for BMI and other health-related variables, the association related to occupational PA became statistically non-significant, while the association related to leisure-time PA remained statistically significant. CONCLUSION: In contrast to previous studies in high-income countries, we found that leisure-time PA was positively associated with hypertension prevalence and occupational PA was associated with a lower hypertension prevalence. This suggests that the association between PA and hypertension might differ depending on the context.

Eating speed and abdominal adiposity in middle-aged adults: a cross-sectional study in Vietnam.

BACKGROUND: Several studies have associated fast eating speed with the risk of general obesity, but there are inadequate data on the association between eating speed and abdominal adiposity which may pose a higher threat to health than general obesity. The present study aimed to investigate the association between eating speed and abdominal obesity in a Vietnamese population. METHODS: Between June 2019 and June 2020, the baseline survey of an ongoing prospective cohort study on the determinants of cardiovascular disease in Vietnamese adults was conducted. A total of 3,000 people aged 40-60 years old (1,160 men and 1,840 women) were recruited from eight communes in the rural district of Cam Lam, Khanh Hoa province, in Central Vietnam. Self-reported eating speed was assessed on a 5-point Likert scale, and responses were collapsed into the following three categories: slow, normal, and fast. Abdominal obesity was defined as a waist-to-height ratio of ≥ 0.5. Poisson regression with a robust variance estimator was used to assess the association between eating speed and abdominal obesity. RESULTS: Compared with slow eating speed, the adjusted prevalence ratio (95% confidence interval) for abdominal obesity was 1.14 (1.05, 1.25)1.14 (1.05, 1.25) for normal eating speed and 1.30 (1.19, 1.41) for fast eating speed (P for trend < 0.001). CONCLUSION: A faster eating speed was associated with a higher prevalence of abdominal obesity in a middle-aged population in rural Vietnam.

Association between parental absence during childhood and metabolic syndrome during adulthood: A cross-sectional study in rural Khanh Hoa, Vietnam.

BACKGROUND: This study aimed to determine the association between parental absence during childhood and metabolic syndrome (MetS) in adulthood among middle-aged adults in rural Khanh Hoa province, Vietnam. Given that broader literature on adverse childhood experiences (ACEs) suggests a strong positive association between ACEs and cardiometabolic risk or diseases, we hypothesized that parental absence during childhood, which is a major component of ACEs, is more likely to cause MetS in adulthood. METHODS: Data were obtained from the baseline survey of the Khanh Hoa Cardiovascular Study, in which 3000 residents aged between 40 to 60 years participated. MetS was assessed using the modified Adult Treatment Panel III (ATP III) criteria. It was considered parental absence if the participants had experienced parental absence due to death, divorce, or out-migration before three or between three to 15 years. We used multiple logistic regression analyses to examine the association between parental absence during childhood and metabolic syndrome during adulthood. RESULTS: There was no significant association between parental absence and MetS; adjusted odds ratio [AOR] was 0.97 (95% confidence interval [CI] = 0.76-1.22) for those who experienced parental absence between three to 15 years and the corresponding figure for those who experienced it before three years was 0.93 (95% CI = 0.72-1.20). No significant associations were observed when these were examined for the causes of parental absence. CONCLUSION: This study did not support our hypothesis of an association between parental absence during childhood and metabolic syndrome during adulthood. Parental absence may not be a predictor of MetS among Vietnamese people in rural communities.

Parental absence during childhood and weight status in adulthood among middle-aged community dwellers in rural Vietnam.

OBJECTIVES: While adverse childhood experiences (ACEs) have been shown to be associated with adulthood obesity, less is known about their association with underweight. We examined the associations between parental absence (i.e., a major component of ACEs) and both underweight and excess weight among middle-aged rural community dwellers in Vietnam, where experiences of parental absence was not uncommon during and after the Vietnam War (1955-1975). METHODS: Data came from 3000 middle-aged adults who participated in the baseline survey of Khánh Hòa Cardiovascular Study. Parental absence was defined as parental absence due to death, divorce, or out-migration. Using information on the timing of such events, we categorized participants into those who experienced parental absence before the age of 3, between the ages of 3 and 15, and those without such experiences. BMI was calculated based on measured height and weight (kg/m2 ) and categorized into three groups: underweight <18.5; normal 18.5-24.9; excess weight ≥ 25. Multinomial logistic regression was then used to investigate the association between parental absence and adult weight status. RESULTS: Parental absence that occurred before the age of 3 was marginally significantly associated with underweight (relative risk ratio [RRR] = 1.44, 95% confidence interval [CI] 0.95, 2.20) but not with overweight/obesity. Parental divorce was associated with overweight/obesity (RRR = 2.48, 95% CI 1.28, 4.81), but not parental absence due to migratory work. CONCLUSIONS: While previous studies in Western settings focused almost exclusively on the risk of obesity in relation to exposure to ACEs, our findings point to the potential importance of considering the risk of underweight in low- and middle-income countries.

Red meat consumption is associated with prediabetes and diabetes in rural Vietnam: a cross-sectional study.

OBJECTIVE: To examine the association between red/processed meat consumption and glycaemic conditions (i.e. prediabetes (preDM) and diabetes mellitus (DM)) among middle-aged residents in rural Khánh Hòa, Vietnam. DESIGN: In this cross-sectional study, a multinomial logistic regression model was used to examine the association between daily consumption of red/processed meat (0-99 g, 100-199 g or ≥ 200 g) and preDM/DM with adjustments for socio-demographic, lifestyle-related and health-related variables. SETTING: Khánh Hòa Province, Vietnam. PARTICIPANTS: The study used data collected through a baseline survey conducted during a prospective cohort study on CVD among 3000 residents, aged 40-60 years, living in rural communes in Khánh Hòa Province. RESULTS: The multinomial regression model revealed that the relative-risk ratios for DM were 1·00 (reference), 1·11 (95 % CI = 0·75, 1·62) and 1·80 (95 % CI = 1·40, 2·32) from the lowest to the highest red/processed meat consumption categories (Ptrend = 0·006). The corresponding values for preDM were 1·00 (reference), 1·25 (95 % CI = 1·01, 1·54) and 1·67 (95 % CI = 1·20, 2·33) (Ptrend = 0·004). We did not find any evidence of statistical significance in relation to poultry consumption. CONCLUSION: Increased red/processed meat consumption, but not poultry consumption, was positively associated with the prevalence of preDM/DM in rural communes in Khánh Hòa Province, Vietnam. Dietary recommendations involving a reduction in red/processed meat consumption should be considered in low- and middle-income countries.

Impact of hepatitis B vaccination programs in Vietnam evaluated by estimating HBsAg prevalence.

Background: Vietnam introduced a 3-dose hepatitis B (HBV) immunization program comprising 1 dose immediately after birth and 2 or 3 in infancy in the past 20 years, but the impact of the vaccine has not been systematically evaluated. Thus, we conducted this survey aiming to estimate the age-specific chronic HBV prevalence in the general population and to evaluate HBV immunization effectiveness. Methods: Population-based, four-stage cluster sampling was used in the South Central Coast region of Vietnam. The point-of-care Determine rapid test was used to assess hepatitis B surface antigen (HBsAg) positivity. Results: A total of 2,075 samples were included in the study. HBsAg prevalence was significantly higher among adults aged 20-39 years than in the population aged 1-19 years (8.0% [95% confidence interval 5.0-12.0] vs. 2.0% [95% confidence interval 1.0-6.0], p<0.01). HBsAg prevalence decreased after implementation of the 3-dose vaccination schedule during infancy from 1997 to 2002, whereas the change in prevalence after implementation of the birth dosing was not significant. A slight increase in HBsAg prevalence was observed for the cohort born in 2011, 2012, and 2013, when there was a vaccine shortage and media reports of immunization resistance. Conclusions: This is the first population-based assessment of the introduction of the HBV vaccine in Vietnam performed by estimating the HBsAg prevalence across a wide range of ages. The results showed that the HBV immunization policy effectively reduces HBsAg prevalence in general, although birth dosing of the vaccine and low immunization coverage should be carefully monitored.

Comparison between a rapid diagnostic test and dried blood spot-based immunoassay for hepatitis B surface antigen testing: Performance and cost implications in a population-based serosurvey in Vietnam.

OBJECTIVES: This study aimed to determine the agreement between a rapid diagnostic test (RDT) and a dried blood spot (DBS)-based electrochemiluminescence immunoassay (ECLIA) of hepatitis B surface antigen and to compare the costs of conducting serosurveys using RDTs and DBS in a field setting. METHODS: A serosurvey was conducted in the South Central Coast region of Vietnam in May 2019. Participants aged 1-39 years were recruited using a four-stage random sampling method and tested for hepatitis B surface antigen using an RDT kit (Alere Determine) and a DBS-based ECLIA. The agreement between the RDT and the DBS-based ECLIA was assessed using cross-tabulation and Cohen kappa. Cost data were categorized by input (personnel, transportation, field consumables, laboratory consumables, and capital item/overhead) and survey phase (survey preparation, data/biospecimen collection, laboratory testing, and coordination). RESULTS: A total of 2072 participants were analyzed. There was a 99% agreement between the RDT and the DBS-based ECLIA results, with a Cohen kappa of 0.9. The estimated cost of conducting a serosurvey by DBS was UD $75,291, whereas RDT was $53,182. CONCLUSION: RDTs and DBS-based ECLIA provide test results with high agreements. RDTs are a better option in terms of cost, whereas the DBS-based ECLIA may be useful when evaluating multiple infectious diseases.

Effect of pneumococcal conjugate vaccine on prevalence of otitis media with effusion among children in Vietnam.

PURPOSE: Otitis media with effusion (OME) is common in young children and is associated with Streptococcus pneumoniae infection. We aimed to determine the impact of pneumococcal conjugate vaccine (PCV) introduction on the prevalence of OME and OME associated with vaccine-type (VT) or non-VT. METHODS: Population-based cross-sectional surveys were conducted in pre- (2016) and post-PCV periods (2017, 2018, and 2019) at selected communes in Nha Trang, Vietnam. For each survey, we randomly selected 60 children aged 4-11 months and 60 aged 14-23 months from each commune. Nasopharyngeal sample collection and tympanic membrane examination by digital otoscope were performed. S. pneumoniae was detected and serotyped by lytA qPCR and microarray. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated using Firth's logistic regression, stratified by age group. RESULTS: Over the four surveys, 2089 children had a bilateral ear examination. Compared to pre-PCV, the prevalence of OME reduced in 2018 (OR 0.51, 95 %CI 0.28-0.93) and in 2019 (OR 0.53, 95 %CI 0.29-0.97) among the <12-month-olds, but no significant reduction among the 12-23-month-olds. The prevalence of OME associated with VT pneumococcus decreased in 2018 and 2019 (2018: OR 0.14, 95 %CI 0.03-0.55; 2019: OR 0.20, 95 %CI 0.05-0.69 in the <12-months-olds, 2018: OR 0.05, 95 %CI 0.00-0.44, 2019: OR 0.41, 95 %CI 0.10-1.61 in the 12-23-months-olds). The prevalence of OME associated with non-VT pneumococcus increased in the 12-23-month-olds in 2017 (OR 3.09, 95 %CI 1.47-7.45) and returned to the pre-PCV level of prevalence in 2018 and 2019 (OR 0.94, 95 %CI 0.40-2.43 and 1.40, 95 %CI 0.63-3.49). CONCLUSION: PCV10 introduction was associated with a reduction of OME prevalence in infants but not in older children.

Association between parental absence during childhood and depressive symptoms in adulthood in rural Vietnam.

BACKGROUND: While parental absence during childhood has been linked to depression/depressive symptoms in adulthood, no research has been conducted on this association in Vietnam, where many children were separated from their parents during and after the Vietnam War (1955-1975). We examined the association between parental absence in childhood and depressive symptoms among rural community dwellers in Khanh Hoa Province, Vietnam. METHODS: Data came from 3000 individuals aged 40-60 years old who participated in the baseline survey of the Khanh Hoa Cardiovascular Study. Depressive symptoms were assessed with the 11-item Center for Epidemiologic Studies Depression Scale. Self-reported information on parental absence due to death, divorce, or outmigration to other locations before the age of 15 was also obtained. A Poisson regression analysis with a robust variance estimator was used to examine associations. RESULTS: Experiencing parental absence at 3 - < 15 years old and before 3 years old was associated with a 1.21 times (95% confidence interval [CI] = 1.02-1.43) and 1.41 times (95% CI = 1.15-1.73) higher prevalence of depressive symptoms, respectively (p trend <0.001). When examining the associations by the different reasons for the parental absence, the strongest association was found for parental absence due to outmigration to other locations. LIMITATIONS: We had no information on who respondents lived with after they experienced parental absence. In addition, self-reported information on childhood experiences was subject to recall bias. CONCLUSIONS: In rural Vietnam, parental absence during childhood was associated with a significantly increased prevalence of depressive symptoms in middle adulthood.

The seroprevalence, waning rate, and protective duration of anti-diphtheria toxoid IgG antibody in Nha Trang, Vietnam.

BACKGROUND: Diphtheria cases reported in Central Vietnam since 2013 were mainly in children aged 6-15 years, which may reflect an immunity gap. There is little information on population immunity against diphtheria in countries without a school-entry booster dose. We aimed to measure the age-stratified seroprevalence of anti-diphtheria toxoid antibodies, quantify the change in antibody levels in individuals over time, and estimate the length of protective immunity after vaccination in well-vaccinated communities in Vietnam. METHODS: An age-stratified seroprevalence survey among individuals aged 0-55 years was conducted at Nha Trang, Vietnam. The same participants were followed up after two years to quantify the change in antibody levels. IgG was measured using ELISA. The length of protective immunity after vaccination was estimated using a mixed-effect linear regression model with random intercept. RESULTS: Overall seroprevalence was 26% (95%CI:20-32%). Age-stratified seroprevalence was 68% (95%CI:4-11%), 7% (95%CI:4-11%), 12% (95%CI:7-19%), 33% (95%CI:27-40%), and 28% (95%CI:17-43%) among those aged ≤5, 6-15,16-25, 26-35, and 36-55 years, respectively. The antibody levels declined by 47% (95%CI:31-59%) over two years, and the predicted duration of vaccine-derived protective immunity after receiving four doses was 4.3 years (95%CI:3.5-5.3) among participants aged six years or younger. CONCLUSION: Given the low seroprevalence and short period of vaccine protection, a school-entry booster dose (5-7 years) is recommended in Vietnam.

Individual-level social capital is associated with depressive symptoms among middle-aged community dwellers in rural Vietnam: a cross-sectional study.

OBJECTIVES: There has been comparatively little research on the association between social capital and depressive symptoms in low- and middle-income countries. To address this deficit this study examined the association among middle-aged adults in rural Vietnam. DESIGN: A cross-sectional study. SETTING: Data came from the baseline survey of the Khánh Hòa Cardiovascular Study, which is an ongoing prospective cohort study aiming to elucidate the determinants of cardiovascular diseases. PARTICIPANTS: A total of 3000 people aged 40-60 years old residing in rural communes in Khánh Hòa province, Vietnam. EXPOSURE OF INTEREST: Cognitive social capital (ie, low, middle and high) and structural social capital (in terms of social participation; yes or no) were assessed via a questionnaire. PRIMARY OUTCOME MEASURE: Depressive symptoms were assessed with the 11-item Center for Epidemiologic Studies Depression Scale. RESULTS: A robust Poisson regression model revealed that adults in the highest versus lowest cognitive social capital tertile had a 61% lower prevalence of depressive symptoms (prevalence ratio (PR)=0.39, 95% CI=0.31 to 0.49). Individuals with higher structural social capital were also significantly less likely to experience depressive symptoms (PR=0.74, 95% CI=0.61 to 0.90). CONCLUSION: In a cohort of 3000 middle-aged rural residents in Vietnam, both cognitive and structural social capital assessed at the individual level were inversely associated with the prevalence of depressive symptoms.

Association of public health interventions and COVID-19 incidence in Vietnam, January to December 2020.

BACKGROUND: Vietnam implemented various public health interventions such as contact tracing and testing, mandatory quarantine, and lockdowns in response to coronavirus disease 2019 (COVID-19). However, the effects of these measures on the epidemic remain unclear. METHODS: This article describes the public health interventions in relation to COVID-19 incidence. Maximum likelihood estimations were used to assess containment delays (time between symptom onset and start of isolation) and multivariable regression was employed to identify associated factors between interventions and COVID-19 incidence. The effective reproductive numbers (Rt) were calculated based on transmission pairs. RESULTS: Interventions were introduced periodically in response to the epidemic. Overall, 817 (55.4%) among 1474 COVID-19 cases were imported. Based on a serial interval of 8.72 ± 5.65 days, it was estimated that Rt decreased to below 1 (lowest at 0.02, 95% CI 0-0.12) during periods of strict border control and contact tracing, and increased ahead of new clusters. The main method to detect cases shifted over time from passive notification to active case-finding at immigration or in lockdown areas, with containment delays showing significant differences between modes of case detection. CONCLUSIONS: A combination of early, strict, and consistently implemented interventions is crucial to control COVID-19. Low-middle income countries with limited capacity can contain COVID-19 successfully using non-pharmaceutical interventions.

Rubella seroprevalence among mothers and incidence of congenital rubella three years after rubella vaccine introduction in Vietnam.

Following a rubella outbreak in 2011, Vietnam implemented a mass measles-rubella vaccination campaign for children aged 1-14 years in 2014-2015, further expanding the target age to 16-17 years in 2016; routine vaccination was introduced in 2014. However, there was concern that a substantial proportion of women of child-bearing age were still susceptible to rubella, with the fear of congenital rubella emergence. Thus, we conducted a prospective cohort study in Nha Trang, Vietnam, from 2017-2018 to investigate pregnant women's susceptibility to rubella infection, the incidence of congenital rubella infection, and factors associated with susceptibility. Cord blood was tested for rubella-specific immunoglobulin M (IgM) and IgG; neonatal saliva and cord blood specimens were examined for rubella-RNA. We analyzed 2013 mother-baby pairs. No baby was rubella-IgM or rubella-RNA positive. Overall, 20.4% of mothers were seronegative (95% confidence interval, 18.6%-22.1%). The seronegativity was significantly low among mothers aged <35 years. We found that maternal age groups of 20-24 and 25-29 years, and the lack of self-reported vaccination history were significantly associated with seronegativity. Many pregnant women who were not covered by the vaccination campaign are still at risk of rubella infection.

Prevalence of mobile colistin resistance (mcr) genes in extended-spectrum ß-lactamase-producing Escherichia coli isolated from retail raw foods in Nha Trang, Vietnam.

The aim of the study was to assess the presence of genes in ESBL-producing E. coli (ESBL-Ec) isolated from retail raw food in Nha Trang, Vietnam. A total of 452 food samples comprising chicken (n = 116), pork (n = 112), fish (n = 112) and shrimp (n = 112) collected between 2015 and 2017 were examined for the prevalence of ESBL-Ec. ESBL-Ec were detected in 46.0% (208/452) of retail food samples, particularly in 66.4% (77/116), 55.4% (62/112), 42.0% (47/112) 19.6% (22/112) of chicken, pork, fish and shrimp, respectively. Sixty-five out of the 208 (31.3%) ESBL-Ec isolates were positive for mcr genes including mcr-1, mcr-3 and both mcr-1 and mcr-3 genes in 56/208 (26.9%), 1/208 (0.5%) and 8/208 (3.9%) isolates, respectively. Particularly, there was higher prevalence of mcr-1 in ESBL-Ec isolates from chicken (53.2%, 41/77) in comparison to shrimp (22.7%, 5/22), pork (11.3%, 7/62) and fish (6.4%, 3/47). mcr-3 gene was detected in co-existence with mcr-1 in ESBL-Ec isolates from shrimp (9.1%, 2/22), pork (8.1%, 5/62) and fish (2.1%, 1/47) but not chicken. The 65 mcr-positive ESBL-Ec (mcr-ESBL-Ec) were colistin-resistant with the MICs of 4-8 µg/mL. All mcr-3 gene-positive isolates belonged to group A, whereas phylogenetic group distribution of isolates harboring only mcr-1 was B1 (44.6%), A (28.6%) and D (26.8%). PFGE analysis showed diverse genotypes, although some isolates demonstrated nearly clonal relationships. S1-PFGE and Southern hybridization illustrated that the mcr-1 and mcr-3 genes were located either on chromosomes or on plasmids. However, the types of mcr genes were harbored on different plasmids with varied sizes of 30-390 kb. Besides, the ESBL genes of CTX-M-1 or CTX-M-9 were also detected to be located on plasmids. Noteworthy, co-location of CTX-M-1 with mcr-1 or mcr-3 genes on the same plasmid was identified. The conjugation experiment indicated that the mcr-1 or mcr-3 was horizontally transferable. All mcr-ESBL-Ec isolates were multidrug resistance (resistance to ≥3 antimicrobial classes). Moreover, ß-Lactamase-encoding genes of the CTX-M-1 (78.5%), CTX-M-9 (21.5%), TEM (61.5%) groups were found in mcr-ESBL-Ec. The astA gene was detected in 27 (41.5%) mcr-ESBL-Ec isolates demonstrating their potential virulence. In conclusion, mcr-1 and mcr-3 genes existed individually or concurrently in ESBL-Ec isolates recovered from retail raw food in Nha Trang city, which might further complicate the antimicrobial-resistant situation in Vietnam, and is a possible health risk for human.