Cost-effectiveness analysis of typhoid vaccination in Lao PDR.

BACKGROUND: Typhoid vaccination has been shown to be an effective intervention to prevent enteric fever and is under consideration for inclusion in the national immunization program in Lao PDR. METHODS: A cost-utility analysis was performed using an age-structured static decision tree model to estimate the costs and health outcomes of introducing TCV. Vaccination strategies combined with five delivery approaches in different age groups compared to no vaccination were considered from the societal perspective, using the Gavi price of 1.5 USD per dose. The vaccination program was considered to be cost-effective if the incremental cost-effectiveness ratio was less than a threshold of 1 GDP per capita for Lao PDR, equivalent to USD 2,535 in 2020. RESULTS: In the model, we estimated 172.2 cases of enteric fever, with 1.3 deaths and a total treatment cost of USD 7,244, based on a birth cohort of 164,662 births without TCV vaccination that was followed over their lifetime. To implement a TCV vaccination program over the lifetime horizon, the estimated cost of the vaccine and administration costs would be between USD 470,934 and USD 919,186. Implementation of the TCV vaccination program would prevent between 14 and 106 cases and 0.1 to 0.8 deaths. None of the vaccination programs appeared to be cost-effective. CONCLUSIONS: Inclusion of TCV in the national vaccination program in Lao PDR would only be cost-effective if the true typhoid incidence is 25-times higher than our current estimate.

Changes in household food security, access to health services and income in northern Lao PDR during the COVID-19 pandemic: a cross-sectional survey.

OBJECTIVES: We assessed the relative difficulty in meeting food needs during the COVID-19 pandemic compared with before; determined the relationship between pandemic-associated difficulties in food access and household, maternal and child food security; and identified resiliency-promoting strategies. DESIGN: A cross-sectional survey of households undertaken in November 2020. SETTING: Rural districts of Luang Prabang Province, Lao People's Democratic Republic. PARTICIPANTS: Households (N=1122) with children under 5 years. PRIMARY AND SECONDARY OUTCOMES MEASURED: Survey respondents reported the relative ease of access of food and healthcare as well as changes in income and expenditures compared with before March 2020. We determined indicators of food security and source of foods consumed for households, women and children, as well as prevalence of malnutrition in children under 5. RESULTS: Nearly four-fifths (78.5%) found it harder to meet household food needs during the pandemic. The most common reasons were increased food prices (51.2%), loss of income (45.3%) and decreased food availability (36.6%). Adjusting for demographics, households with increased difficulty meeting food needs had lower food consumption scores and child dietary diversity. Over 85% of households lost income during the pandemic. Decreased expenditures was associated with reliance on more extreme coping strategies to meet food needs. The households who experienced no change in meeting food needs produced a greater percentage of their food from homegrown methods (4.22% more, 95% CI 1.28 to 7.15), than households who found it more difficult. CONCLUSIONS: Pandemic-associated shocks may have large effects on food insecurity. Action is needed to mitigate consequences of the pandemic on nutrition. Local food production and safety net programmes that offset income losses may help.

Factors associated with cervical cancer screening among women aged 25-60 years in Lao People's Democratic Republic.

BACKGROUND: Despite cervical cancer being a major public health concern in the Lao People's Democratic Republic (Lao PDR), screening coverage is very low. The reasons and factors for this are unknown. This study aimed to identify factors associated with uptake of cervical cancer screening among women aged 25-60 years. METHODS: The case-control study was conducted among women aged 25-60 years in Vientiane Capital and Luang Prabang province from March 15 to May 31, 2018. A total of 360 women were included in the study, a ratio of two controls per case. The cases were women who had undergone cervical cancer screening over the last five years. The controls were women who had never been screened or screened more than five years before, matched to the cases with residency and age (± five years). The cases were selected from central and provincial hospitals and the controls from the same community and districts where the cases resided. Conditional logistic regression was used to determine factors associated with cervical cancer screening. RESULTS: The mean age was 42.37±9.4 years (range: 25-60), 66.67% were women from Vientiane Capital, and 86.11% were married. The common reasons for not being screened were the absence of clinical signs and symptoms (45.28%) followed by never having heard about cervical cancer (13.33%). In the multivariable analyses, we found that having sexually transmitted infections (AOR = 3.93; 95% CI = 1.92-8.05), receiving recommendations for screening from health workers (AOR = 3.85; 95% CI = 1.90-7.78), a high score for knowledge (AOR = 7.90; 95% CI = 2.43-25.69) and attitude towards cervical cancer prevention and treatment (AOR = 2.26; 95% CI = 1.18-7.16), and having a car to travel (AOR = 2.97; 95% CI = 1.44-6.11) had a positive impact on undergoing cervical cancer screening. CONCLUSION: Gynecological consultations, increased knowledge and positive attitudes result in women undergoing screening. Therefore, health education and advocacy for cervical cancer prevention should be provided to women.

Cost-effectiveness of seasonal influenza vaccination in pregnant women, healthcare workers and adults >= 60 years of age in Lao People's Democratic Republic.

BACKGROUND: Pregnant women, healthcare workers (HW), and adults >= 60 years have shown an increased vulnerability to seasonal influenza virus infections and/or complications. In 2012, the Lao People's Democratic Republic (Lao PDR) initiated a national influenza vaccination program for these target groups. A cost-effectiveness evaluation of this program was undertaken to inform program sustainability. METHODS: We designed a decision-analytical model and collected influenza-related medical resource utilization and cost data, including indirect costs. Model inputs were obtained from medical record abstraction, interviews of patients and staff at hospitals in the national influenza sentinel surveillance system and/or from literature reviews. We compared the annual disease and economic impact of influenza illnesses in each of the target groups in Lao PDR under scenarios of no vaccination and vaccination, and then estimated the cost-effectiveness of the vaccination program. We performed sensitivity analyses to identify influential variables. RESULTS: Overall, the vaccination of pregnant women, HWs, and adults >= 60 years could annually save 11,474 doctor visits, 1,961 days of hospitalizations, 43,027 days of work, and 1,416 life-years due to laboratory-confirmed influenza illness. After comparing the total vaccination program costs of 23.4 billion Kip, to the 18.4 billion Kip saved through vaccination, we estimated the vaccination program to incur a net cost of five billion Kip (599,391 USD) annually. The incremental cost per life-year saved (ICER) was 44 million Kip (5,295 USD) and 6.9 million Kip (825 USD) for pregnant women and adults >= 60 years, respectively. However, vaccinating HWs provided societal cost-savings, returning 2.88 Kip for every single Kip invested. Influenza vaccine effectiveness, attack rate and illness duration were the most influential variables to the model. CONCLUSION: Providing influenza vaccination to HWs in Lao PDR is cost-saving while vaccinating pregnant women and adults >= 60 is cost-effective and highly cost-effective, respectively, per WHO standards.

Hepatitis B virus in Lao dentists: A cross-sectional serological study.

INTRODUCTION AND OBJECTIVES: Hepatitis B virus (HBV) is endemic in Lao PDR, with up to 10% chronic infections in adults. Dentists have high risk of exposure and transmission to their patients. The aim was to investigate the serological profiles of vaccination, exposure and susceptibility to HBV. In addition, we determined the knowledge, attitude and practice (KAP) of Lao dentists toward HBV. MATERIALS AND METHODS: Dentists and dental assistants were recruited from 186 private dental clinics in Vientiane Capital. They completed a KAP questionnaire and serum was tested by ELISA for HBV markers (anti-HB surface antigen, anti-core antigen, HBV surface antigen). RESULTS: 206 dentists and 111 dental workers aged between 18-63 years were included. Serology data showed that 37.8% had previous exposure (49.0% of males and 32.4% of females) and 5.0% were chronically infected (7.7% of males and 3.8% of females). Less than 15% had serological evidence of vaccination and 66.8% were unprotected against infection. Knowledge of HBV was mostly low, for example 61.8% were aware of the childhood HBV vaccine. Just over half said that they should give dental care to HBV carriers. About one quarter reported accidental blood exposure during the last 6 months but knowledge about procedures after exposure was low. CONCLUSIONS: Lao dentists are at high risk of occupational exposure to HBV but have low awareness and serological protection. There is a need to introduce mandatory vaccination, to strengthen occupational health in health care providers and to further develop the academic curricula of dental students.

Timeliness of immunisation with the pentavalent vaccine at different levels of the health care system in the Lao People's Democratic Republic: A cross-sectional study.

BACKGROUND: The timely administration of vaccines is considered to be important for both individual and herd immunity. In this study, we investigated the timeliness of the diphtheria-tetanus-whole cell pertussis-hepatitis B-Haemophilus influenzae type b (pentavalent) vaccine, scheduled at 6, 10 and 14 weeks of age in the Lao People's Democratic Republic. We also investigated factors associated with delayed immunization. METHODS: 1162 children aged 8-28 months who had received the full course of the pentavalent vaccine at different levels of the health care system were enrolled. Vaccination dates documented in hospital records and/or immunisation cards were recorded. Age at vaccination and time intervals between doses were calculated. Predictors for timely completion with the pentavalent vaccine at 24 weeks were assessed by bivariate and multivariable analyses. RESULTS: Several discrepancies in dates between vaccination documents were observed. In general, vaccination with the pentavalent vaccine was found to be delayed, especially in health care settings below the provincial hospital level. Compared to the central hospital level, less participants who were vaccinated at the district/health center level received the third dose by 16 (48% at the central hospital level vs. 7.1% at the district and 12.4% at the health center level) and 24 weeks of age (94.4% at the central hospital level vs 64.6% at the district-outreach and 57.4% at the health center level) respectively. In logistic regression analyses, lower education level of the mother as well as vaccination by outreach service, were independently associated with delayed completion of vaccination. CONCLUSION: We observed a general delay of vaccination, especially at lower ranked facilities, which correlated with indicators of poor access to health services. This highlights the need for further improving health equity in rural areas. Age-appropriate vaccination should become a quality indicator for the national immunization programme. In addition, we recommend further training of the health care staff regarding the importance of reliable documentation of dates.

Pertussis in Lao PDR: Seroprevalence and disease.

OBJECTIVES: Pertussis is a debilitating vaccine-preventable infection. The aim of this study was to determine susceptibility and exposure to pertussis in Lao PDR in different age groups and subpopulations. METHODS: A total 3072 serum samples were obtained from different cohorts: children with documented vaccination, pre-schoolers, schoolchildren, blood donors, healthcare workers (HCWs), and pregnant women and paired cord blood. Samples were tested for anti-pertussis toxin IgG antibodies. A history of Bordetella pertussis exposure was defined according to antibody titres. Four hundred and seventy-five throat swabs and nasopharyngeal aspirates were analysed by PCR for the presence of B. pertussis in symptomatic children at the Children's Hospital in Vientiane. RESULTS: Overall pertussis seroprevalence was 57.5%. The prevalence of titres indicating acute infection or recent vaccination or infection/vaccination within the last 12 months ranged from 7.4% (100/1356) in adults to 21.4% (25/117) in pre-schoolers (age 1-5 years). B. pertussis was detected in 1.05% (5/475) of children with respiratory symptoms in Vientiane Capital. CONCLUSIONS: It is suggested that routine childhood vaccination, in particular outreach, as well as vaccination of HCWs should be strengthened. A childhood booster and vaccination of pregnant mothers should be considered. There is also a need to improve reporting and to introduce pertussis testing in at least one central facility.

Hepatitis A Virus in Lao People's Democratic Republic: Seroprevalence and Risk Factors.

Despite several recent reports of outbreaks of hepatitis A, little is known about the disease burden in Lao People's Democratic Republic (PDR). We conducted a cross-sectional age-stratified seroprevalence study of anti-hepatitis A virus (HAV) IgG and risk factors in a rural province (Xiengkhouang) and Vientiane capital in Lao PDR. Overall, 62% of participants were anti-HAV positive in Xiengkhouang Province compared with 45.5% in Vientiane capital. In Xiengkhouang, 23.7% of 5- to 10-year-olds were already seropositive compared with 5% in Vientiane. A dramatic increase in seroprevalence occurred between 15- to 20-year and 21- to 30-year age-groups (35.7-62.4%, Xiengkhouang, and 11.5-69.7%, Vientiane) until essentially all older adults were positive in both locations. The main risk factors for HAV antibodies were age, non-Lao-Tai ethnicity, and food-related risk factors. In conclusion, Lao children seem to be exposed very early to HAV, particularly in rural settings, and exposure continues throughout their lives, mostly without being reported. In the older birth cohorts, the high seroprevalence may largely reflect poor sanitation and exposure during childhood. In Vientiane capital, the lower seroprevalence at young ages may reflect better water sanitation since the late 1990s. A comparison with neighboring Thailand indicates that the impact of improved sanitation in Lao PDR began only two decades later. Further improvements in water sanitation, in particular in the rural districts, and better food hygiene are warranted. Our study also suggests that HAV infections are underreported. Improved reporting would provide guidance for targeted interventions to further reduce HAV infections.

Estimation of Incidence of Typhoid and Paratyphoid Fever in Vientiane, Lao People's Democratic Republic.

Typhoid conjugate vaccines represent a new tool for typhoid control. However, incidence data are needed to inform decisions about introduction. We sought to estimate typhoid and paratyphoid fever incidence in Vientiane, the capital and largest city of the Lao People's Democratic Republic (Lao PDR). We did a representative cluster survey of health-seeking behavior for fever in Vientiane from January 15, 2019 through January 26, 2019. Multipliers derived from the survey were applied to data from Salmonella Typhi and Salmonella Paratyphi A bloodstream infection surveillance from Mahosot Hospital, Vientiane, for the period of January 1, 2015 through December 31, 2017, to estimate enteric fever incidence. A total of 336 households representing 1,740 persons were enrolled in the healthcare utilization survey, and multipliers were derived based on responses to questions about healthcare seeking in the event of febrile illness. Of 7,997 Vientiane residents receiving blood cultures over the 2-year surveillance period at Mahosot Hospital, we identified 16 (0.2%) with Salmonella Typhi and six (< 0.1%) with Salmonella Paratyphi A bloodstream infection. After applying multipliers, we estimated that the annual incidence of typhoid was 4.7 per 100,000 persons and paratyphoid was 0.5 per 100,000 persons. During the study period, the incidence of typhoid and paratyphoid fever was low in Vientiane. Ongoing surveillance is warranted to identify increases in future years. Similar studies elsewhere in the Lao PDR would be useful to understand the wider enteric fever situation in the country.

Lasting benefit of infant hepatitis B vaccination in adolescents in the Lao People's Democratic Republic.

OBJECTIVES: Hepatitis B is endemic in Lao PDR with 8-10% of the adult population being chronically infected. We investigated the impact of hepatitis B vaccination on infection in adolescents born shortly before and after the introduction of the vaccine in 2001. METHODS: 779 students from Vientiane Capital and Bolikhamxay province were tested for HBV markers by ELISA. Socio-demographic information was collected with a standardized questionnaire. Predictors/risk factors for seroprotection or exposure to hepatitis B infection were assessed by bivariate and multivariable analyses. RESULTS: The prevalence of a serological vaccination profile increased significantly after the introduction of the vaccine (13.2%-21.9%, p < 0.05, in Vientiane; 3.0%-19.7%, p < 0.001, in Bolikhamxay), which translated into at least a 2-times lower prevalence of past infection. In logistic regression, older students in Bolikhamxay were less likely to be vaccinated and more likely to have been infected by HBV in the past. CONCLUSION: Even though this study documented a sizable and lasting reduction in past hepatitis B infections in adolescents born after the introduction of infant hepatitis B vaccination, the overall levels of protective anti-HBs were low and warrant at least the introduction of a booster for adolescents. Furthermore, we suggest improving the coverage of the hepatitis B birth dose.

Seroprevalence of anti-tetanus antibodies in mothers and cord blood and associated factors in health-care settings in Lao People's Democratic Republic.

BACKGROUND: Maternal neonatal tetanus (MNT) was eliminated from Lao People's Democratic Republic (PDR) in 2014. WHO recommends 80% coverage of 2 or more tetanus vaccinations (TT2+) in pregnancy to maintain MNT control. Vaccination coverage in Lao PDR varies among regions although the reasons are not clear. METHODS: 185 pregnant women giving birth in three district hospitals in Savannakhet province, Lao PDR were recruited. A questionnaire was administered to determine factors associated with seroprotection and blood was taken from mother and cord blood to be tested for anti-tetanus antibodies by ELISA. RESULTS: 77% of mothers and 79% of newborns had sufficiently protective antibody titres (>0.5 IU/ml) against tetanus. Only 70% of the mothers received one dose of TT vaccination during antenatal care (ANC) consultation and 45% received the recommended two injections. Although most of the vaccination took place during ANC 1 and 2, many were missed at these time-points. Anti-tetanus seroprotection in the mothers was associated with maternal age, number of ANC visits, number of TT vaccinations during and before pregnancy and gestational age. CONCLUSION: Seroprevalence of anti-tetanus antibodies in mothers and newborns was intermediate but TT2+ coverage was low in healthcare settings in Lao PDR. TT2+ coverage during ANC is likely to be significantly lower in settings with less robust ANC practices. Missed opportunities to vaccinate in ANC 1 and 2 suggest a need to promote vaccine awareness and vaccination at first ANC visit. A booster dose of TT containing vaccine should be considered for children aged between 4 and 7 years old.

First insights into the genetic characteristics and drug resistance of Mycobacterium tuberculosis population collected during the first national tuberculosis prevalence survey of Lao PDR (2010-2011).

BACKGROUND: In Lao People's Democratic Republic (PDR), tuberculosis (TB) prevalence was estimated at 540/100,000 in 2011. Nevertheless, little is known about the genetic characteristics and anti-TB drug resistance of the Mycobacterium tuberculosis population. The main objective of this work was to study the genetic characteristics and drug resistance of M. tuberculosis population collected during the first National TB Prevalence Survey (TBPS) of Lao PDR (2010-2011). METHODS: Two hundred and twenty two isolates collected during TBPS (2010-2011) were analyzed with the GenoType MTBDRplus test for M. tuberculosis identification and drug resistance detection. Then, 206 of the 222 isolates were characterized by spoligotyping and MIRU-VNTR typing. RESULTS: Among the 222 M. tuberculosis isolates, 11 were mono-resistant to isoniazid and 2 were resistant to isoniazid and rifampicin (MDR-TB), using the GenoType MTBDRplus test. Among the 202 genetically characterized isolates, the East African-Indian (EAI) family was predominant (76.7%) followed by the Beijing (14.4%) and T (5.5%) families. EAI isolates came from all the country provinces, whereas Beijing isolates were found mainly in the northern and central provinces. A higher proportion of Beijing isolates was observed in people younger than 35 years compared to EAI. Moreover, the percentage of drug resistance was higher among Beijing (17.2%) than EAI (5.2%) isolates, and the two MDR-TB isolates belonged to the Beijing family. Combined analysis of the MIRU-VNTR and spoligotyping results (n = 202 isolates) revealed an estimated clustering rate of 11% and the occurrence of mini-outbreaks of drug-resistant TB caused by Beijing genotypes. CONCLUSIONS: The EAI family, the ancient and endemic family in Asia, is predominant in Lao PDR whereas the prevalence of Beijing, the most harmful M. tuberculosis family for humans, is still low, differently from neighboring countries. However, its association with drug resistance, its presence in young patients and its potential association with recent transmission suggest that the Beijing family could change TB epidemiological pattern in Lao PDR. Therefore, efficient TB control and surveillance systems must be maintained and reinforced to prevent the emergence of highly transmissible and drug-resistant strains in Lao PDR, as observed in neighboring countries.

Modeling household dynamics on Respiratory Syncytial Virus (RSV).

Respiratory Syncytial Virus (RSV) is the most common cause of respiratory tract infection in infants and children and shows increasing trend among elderly people worldwide. In many developing country settings, population and household structures have gone through some significant changes in the past decades, namely fewer births, more elderly population, and smaller household size but more RSV high-risk individuals. These dynamics have been captured in a mathematical model with RSV transmission dynamics to predict the disease burden on the detailed population for future targeted interventions. The population and disease dynamics model was constructed and tested against the hospitalization data for Acute Lower Respiratory Tract Infection due to RSV in rural Thai settings between 2005 and 2011. The proportion of extended families is predicted to increase by about 10% from 2005 to 2020, especially for those with elderly population, while the classic nuclear family type (with adults and children) will decline by about 10%. For RSV, infections from extended family type (approximately 60% of all household types) have majorly contributed to the force of infection (FOI). While the model predicted the increase of FOI from the extended family by 15% from 2005 to 2020, the FOI contributed by other household types would be either stable or decrease in the same time period. RSV incidence rate is predominantly high among babies (92.2%) and has been predicted to decrease slightly over time (from 940 to 864 cases per 100,000 population by 2020), while the incidence rates among children and elderly people may remain steadily low over the same period. However, the estimated incidence rates among elderly people were twice than those in children. The model predicts that approximately 60% of FOI for RSV will come from members of the extended family type. The incidence rate of RSV among children and elderly in extended families was about 20 times lower than that in infants and the trend is steady. Targeted intervention strategies, such as health education in some specific groups and targeted vaccination, may be considered, with the focus on extended family type. Target interventions on babies can lessen the transmission to children and elderly especially when transmission within households of extended family type is high.

A Population Dynamic Model to Assess the Diabetes Screening and Reporting Programs and Project the Burden of Undiagnosed Diabetes in Thailand.

Diabetes mellitus (DM) is rising worldwide, exacerbated by aging populations. We estimated and predicted the diabetes burden and mortality due to undiagnosed diabetes together with screening program efficacy and reporting completeness in Thailand, in the context of demographic changes. An age and sex structured dynamic model including demographic and diagnostic processes was constructed. The model was validated using a Bayesian Markov Chain Monte Carlo (MCMC) approach. The prevalence of DM was predicted to increase from 6.5% (95% credible interval: 6.3-6.7%) in 2015 to 10.69% (10.4-11.0%) in 2035, with the largest increase (72%) among 60 years or older. Out of the total DM cases in 2015, the percentage of undiagnosed DM cases was 18.2% (17.4-18.9%), with males higher than females (p-value < 0.01). The highest group with undiagnosed DM was those aged less than 39 years old, 74.2% (73.7-74.7%). The mortality of undiagnosed DM was ten-fold greater than the mortality of those with diagnosed DM. The estimated coverage of diabetes positive screening programs was ten-fold greater for elderly compared to young. The positive screening rate among females was estimated to be significantly higher than those in males. Of the diagnoses, 87.4% (87.0-87.8%) were reported. Targeting screening programs and good reporting systems will be essential to reduce the burden of disease.

Modelling population dynamics and seasonal movement to assess and predict the burden of melioidosis.

BACKGROUND: Melioidosis is an infectious disease that is transmitted mainly through contact with contaminated soil or water, and exhibits marked seasonality in most settings, including Southeast Asia. In this study, we used mathematical modelling to examine the impacts of such demographic changes on melioidosis incidence, and to predict the disease burden in a developing country such as Thailand. METHODOLOGY/PRINCIPAL FINDINGS: A melioidosis infection model was constructed which included demographic data, diabetes mellitus (DM) prevalence, and melioidosis disease processes. The model was fitted to reported melioidosis incidence in Thailand by age, sex, and geographical area, between 2008 and 2015, using a Bayesian Markov Chain Monte Carlo (MCMC) approach. The model was then used to predict the disease burden and future trends of melioidosis incidence in Thailand. Our model predicted two-fold higher incidence rates of melioidosis compared with national surveillance data from 2015. The estimated incidence rates among males were two-fold greater than those in females. Furthermore, the melioidosis incidence rates in the Northeast region population, and among the transient population, were more than double compared to the non-Northeast region population. The highest incidence rates occurred in males aged 45-59 years old for all regions. The average incidence rate of melioidosis between 2005 and 2035 was predicted to be 11.42 to 12.78 per 100,000 population per year, with a slightly increasing trend. Overall, it was estimated that about half of all cases of melioidosis were symptomatic. In addition, the model suggested a greater susceptibility to melioidosis in diabetic compared with non-diabetic individuals. CONCLUSIONS/SIGNIFICANCE: The increasing trend of melioidosis incidence rates was significantly higher among working-age Northeast and transient populations, males aged ≥45 years old, and diabetic individuals. Targeted intervention strategies, such as health education and awareness raising initiatives, should be implemented on high-risk groups, such as those living in the Northeast region, and the seasonally transient population.

Seroprotection at Different Levels of the Healthcare System After Routine Vaccination With Diphtheria-Tetanus-Pertussis whole cell-Hepatitis B-Haemophilus influenzae Type B in Lao People's Democratic Republic.

BACKGROUND: The Lao People's Democratic Republic continues to sustain a considerable burden of vaccine-preventable diseases because of incomplete vaccine coverage and weak vaccine responses. We have assessed seroconversion after routine vaccination with the pentavalent vaccine to capture weaknesses of vaccine management at the different levels of the healthcare system. METHODS: A total of 1151 children (aged 8-28 months) with 3 documented doses of the pentavalent vaccine delivered at central hospitals in Vientiane and the provincial hospital, 3 district hospitals, and 10 health centers in Bolikhamxay province were enrolled. Sociodemographic information was collected with a standardized questionnaire. Serum samples were analyzed for antibodies against vaccine components, and bivariate and multivariable analyses were performed to identify risk factors for low vaccine responses. RESULTS: Seroprotection rates at the provincial, district, and health center level were as high as in central hospitals, but seroprotection rates in areas covered by remote health centers were significantly lower. Protective levels also rapidly decreased with age at sampling. Seroprotection rates in Bolikhamxay against the different components reached 70%-77% and were up to 20% higher than in previous studies in the same region; 18.8% more children received the hepatitis B vaccine birth dose and the hepatitis B virus infection rate was 4 times lower. CONCLUSIONS: Vaccine immunogenicity has dramatically improved in a central province, likely due to training and investment in the cold chain. Nevertheless, there remains a need to focus on the "last mile" in remote areas were most children are vaccinated through outreach activities.

Towards malaria elimination in Savannakhet, Lao PDR: mathematical modelling driven strategy design.

BACKGROUND: The number of Plasmodium falciparum malaria cases around the world has decreased substantially over the last 15 years, but with the spread of resistance against anti-malarial drugs and insecticides, this decline may not continue. There is an urgent need to consider alternative, accelerated strategies to eliminate malaria in countries like Lao PDR, where there are a few remaining endemic areas. A deterministic compartmental modelling tool was used to develop an integrated strategy for P. falciparum elimination in the Savannakhet province of Lao PDR. The model was designed to include key aspects of malaria transmission and integrated control measures, along with a user-friendly interface. RESULTS: Universal coverage was the foundation of the integrated strategy, which took the form of the deployment of community health workers who provided universal access to early diagnosis, treatment and long-lasting insecticidal nets. Acceleration was included as the deployment of three monthly rounds of mass drug administration targeted towards high prevalence villages, with the addition of three monthly doses of the RTS,S vaccine delivered en masse to the same high prevalence sub-population. A booster dose of vaccine was added 1 year later. The surveillance-as-intervention component of the package involved the screening and treatment of individuals entering the simulated population. CONCLUSIONS: In this modelling approach, the sequential introduction of a series of five available interventions in an integrated strategy was predicted to be sufficient to stop malaria transmission within a 3-year period. These interventions comprised universal access to early diagnosis and adequate treatment, improved access to long-lasting insecticidal nets, three monthly rounds of mass drug administration together with RTS,S vaccination followed by a booster dose of vaccine, and screening and treatment of imported cases.

Economic Evaluation of Screening Strategies Combined with HPV Vaccination of Preadolescent Girls for the Prevention of Cervical Cancer in Vientiane, Lao PDR.

BACKGROUND: Several approaches to reduce the incidence of invasive cervical cancers exist. The approach adopted should take into account contextual factors that influence the cost-effectiveness of the available options. OBJECTIVE: To determine the cost-effectiveness of screening strategies combined with a vaccination program for 10-year old girls for cervical cancer prevention in Vientiane, Lao PDR. METHODS: A population-based dynamic compartment model was constructed. The interventions consisted of a 10-year old girl vaccination program only, or this program combined with screening strategies, i.e., visual inspection with acetic acid (VIA), cytology-based screening, rapid human papillomavirus (HPV) DNA testing, or combined VIA and cytology testing. Simulations were run over 100 years. In base-case scenario analyses, we assumed a 70% vaccination coverage with lifelong protection and a 50% screening coverage. The outcome of interest was the incremental cost per Disability-Adjusted Life Year (DALY) averted. RESULTS: In base-case scenarios, compared to the next best strategy, the model predicted that VIA screening of women aged 30-65 years old every three years, combined with vaccination, was the most attractive option, costing 2 544 international dollars (I$) per DALY averted. Meanwhile, rapid HPV DNA testing was predicted to be more attractive than cytology-based screening or its combination with VIA. Among cytology-based screening options, combined VIA with conventional cytology testing was predicted to be the most attractive option. Multi-way sensitivity analyses did not change the results. Compared to rapid HPV DNA testing, VIA had a probability of cost-effectiveness of 73%. Compared to the vaccination only option, the probability that a program consisting of screening women every five years would be cost-effective was around 60% and 80% if the willingness-to-pay threshold is fixed at one and three GDP per capita, respectively. CONCLUSIONS: A VIA screening program in addition to a girl vaccination program was predicted to be the most attractive option in the health care context of Lao PDR. When compared with other screening methods, VIA was the primary recommended method for combination with vaccination in Lao PDR.

The economic evaluation of human papillomavirus vaccination strategies against cervical cancer in women in Lao PDR: a mathematical modelling approach.

BACKGROUND: Cervical cancer, a preventable disease, is the third leading cause of cancer morbidity and mortality in the Lao People's Democratic Republic (Lao PDR). Since many cervical cancers are linked to human papilloma virus (HPV) infection, vaccination against this virus may lead to a reduction in these types of cancer. The study described here is the first to compare the cost-effectiveness of different HPV vaccination options in Lao PDR. METHODS: A dynamic compartment model was created. The model included routine screening activities already in place, as well as theoretical interventions that included a 10-year old girl-only vaccination programme combined with/without a 10-year old boy vaccination programme and/or a catch-up component. The simulation was run over 100 years. In base case analyses, we assumed 70 % vaccination coverage with lifelong protection and 100 % efficacy against HPV types 16/18. The outcomes of interest were the incremental cost per Disability-Adjusted Life Year (DALY) averted. RESULTS: In base case analyses, according to the WHO definition of cost-effectiveness thresholds, vaccinating 10-year-old girls was very cost-effective. Adding a catch-up vaccination element for females aged 11-25 years was also very cost-effective, costing 1559 international dollars (I$) per DALY averted. Increasing the age limit of the catch-up vaccination component to 75 years old showed that this remained a cost-effective option (I$ 5840 per DALY averted). Adding a vaccination programme for 10-year-old boys was not found to be cost-effective unless a short time simulation (30 years or less) was considered, along with a catch-up vaccination component for both males and females. CONCLUSIONS: Adding a catch-up female vaccination component is more attractive than adding a 10-year-old boy vaccination component.

Accuracy of Combined Visual Inspection with Acetic Acid and Cervical Cytology Testing as a Primary Screening Tool for Cervical Cancer: a Systematic Review and Meta-Analysis.

BACKGROUND: The performance of combined testing visual inspection with acetic acid (VIA) and cervical cytology tests might differ from one setting to another. The average estimate of the testing accuracy across studies is informative, but no meta-analysis has been carried out to assess this combined method. OBJECTIVE: The objective of this study was to estimate the average sensitivity and specificity of the combined VIA and cervical cytology tests for the detection of cervical precancerous lesions. MATERIALS AND METHODS: We conducted a systematic review and a meta-analysis, according to the Cochrane Handbook for Systematic Review of Diagnostic Test Accuracy. We considered two cases. In the either-positive result case, a positive result implies positivity in at least one of the tests. A negative result implies negativity in both tests. In the both-positive case, a positive result implies having both tests positive. Eligible studies were identified using Pubmed, Embase, Website of Science, CINHAL and COCRANE databases. True positive, false positive, false negative and true negative values were extracted. Estimates of sensitivity and specificity, positive and negative likelihood (LR) and diagnostic odds ratios (DOR) were pooled using a hierarchical random effect model. Hierarchical summary receiver operating characteristics (HSROC) were generated and heterogeneity was verified through covariates potentially influencing the diagnostic odds ratio. FINDINGS: Nine studies fulfilled inclusion criteria and were included in the analysis. Pooled estimates of the sensitivities of the combined tests in either-positive and both-positive cases were 0.87 (95% CI: 0.83-0.90) and 0.38 (95% CI: 0.29-0.48), respectively. Corresponding specificities were 0.79 (95% CI: 0.63-0.89) and 0.98 (95% CI: 0.96-0.99) respectively. The DORs of the combined tests in either-positive or both-positive result cases were 27.7 (95% CI: 12.5-61.5) and 52 (95% CI: 22.1-122.2), respectively. When including only articles without partial verification bias and also a high-grade cervical intraepithelial neoplasia as a threshold of the disease, DOR of combined test in both-positive result cases remained the highest. However, DORs decreased to 12.1 (95% CI: 6.05-24.1) and 13.8 (95% CI: 7.92-23.9) in studies without partial verification bias for the combined tests in the either-positive and both-positive result cases, respectively. The screener, the place of study and the size of the population significantly influenced the DOR of combined tests in the both-positive result case in restriction analyses that considered only articles with CIN2+ as disease threshold. CONCLUSIONS: The combined test in the either-positive result case has a high sensitivity, but a low specificity. These results suggest that the combined test should be considered in developing countries as a primary screening test if facilities exist to confirm, through colposcopy and biopsy, a positive result.