The Status of Adolescent Testing and Treatment in PEPFAR-Supported Programs, October 2017 to September 2020.

BACKGROUND: Adolescents have poorer outcomes across the HIV cascade compared with adults. We aimed to assess progress in HIV case finding, antiretroviral treatment (ART), viral load coverage (VLC), and viral load suppression (VLS) among adolescents enrolled in the US President's Emergency Plan for AIDS Relief (PEPFAR)-supported programs over a 3-year period that included the beginning of the COVID-19 pandemic. METHODS: We analyzed PEPFAR program data in 28 countries/regions for adolescents aged 10-19 years between year 1 (October 2017to September 2018), year 2 (October 2018 to September 2019), and year 3 (October 2019 to September 2020). We calculated the number and percent change for HIV tests, HIV-positive tests, and total number on ART. Calculated indicators included positivity, percent of positives newly initiated on ART (ART linkage), VLC (percent of ART patients on ART for ≥6 months with a documented viral load result within the past 12 months), and VLS (percent of viral load tests with <1000 copies/mL). RESULTS: Between years 1 and 3, the number of HIV tests conducted decreased by 44.2%, with a 29.1% decrease in the number of positive tests. Positivity increased from 1.3%-1.6%. The number of adolescents receiving ART increased by 10.4%. In addition, ART linkage increased (77.8%-86.7%) as did VLC (69.4%-79.4%) and VLS (72.8%-81.5%). CONCLUSIONS: Our findings demonstrate PEPFAR's success in increasing the adolescent treatment cohort. We identified ongoing gaps in adolescent case finding, linkage, VLC, and VLS that could be addressed with a strategic mix of testing strategies, optimal ART regimens, and adolescent-focused service delivery models.

The procurement and supply chain strengthening project: improving public health supply chains for better access to HIV medicines, Uganda 2011-2016.

BACKGROUND: With countries moving towards reaching the UNAIDS 90-90-90 goal to achieve HIV epidemic control, there are going to be an unprecedented number of persons who will need to be tested, treated, and regularly monitored for viral suppression. However, most of the countries with the greatest burden of HIV/AIDS experience regular stock outages which could be detrimental to reaching these targets. ART and other commodities such as HIV test kits and laboratory supplies need to be readily and consistently available to achieve these targets. The main objective was to improve access to HIV/AIDS related commodities and strengthening institutional capacity for the management of HIV/AIDS logistics services through the MAUL procurement and supply chain strengthening project (PSSP) that rolled out four interventions on mentorship and support supervision, stock level monitoring, spatial visualization of stock indicators using GIS, and using WhatsApp to submit order reports as photo images. METHODS: Medical Access Uganda Limited, a private-not-for-profit supply chain management company in Uganda, implemented these interventions as part of a procurement and supply chain strengthening project (PSSP). These interventions were evaluated using performance monitoring indicators from 2011-2016. We tested for the significance in the change in scores of performance monitoring indicators using the test for difference in proportions. Health facilities were scored on 6 categories and accredited as bronze, silver or gold based on their total scores. Kaplan-Meier estimates were computed for time to silver, and gold ranking and univariate and multivariate Cox proportional hazards models were computed for time to gold ranking. RESULTS: We observed a significant reduction in reported stock-outs from 46 to 4% (p < 0.001) in the analysis period. Accurate stock card inventory rose from 79 to 91% (p < 0.001); adequate stock levels rose from 54 to 71% (p = 0.002) and stock reporting rates from 91 to 100% (p < 0.001). The stock order fill rate improved from a high of 93% to 97% (p = 0.375). Patient load (medium vs low adjusted hazard ratio (aHR): 2.19, p = 0.026; high vs low aHR: 2.97, p = 0.034) and number of support supervision visits (6-10 aHR: 3.33, p = 0.024; > 10 aHR: 5.78, p = 0.003) were associated with better stock management ranking scores. CONCLUSIONS: Improvements in supply chain management in countries committed to achieving the 90-90-90 goals are crucial to achieving HIV epidemic control. Health system strengthening and mentorship investments in Uganda were feasible and are essential for sustainable disease control efforts.

Is it time to use nucleic acid amplification tests for identification of persons with sexually transmitted infections?: evidence from seroprevalence and behavioral epidemiology risk surveys in men with chlamydia and gonorrhea.

Chlamydia and gonorrhea are common sexually transmitted infections (STIs) that can cause multiple problems, and can be easily treated, but frequently present without symptoms. Because of this, commonly used syndromic diagnosis misses a majority of infected persons. Previously, diagnostic tests were expensive and invasive, but newer nucleic-acid amplification tests (NAATs) are available that use urine to non-invasively test for these infections. These analyses used data from seroprevalence studies conducted in five militaries. Data included self-reported current symptoms of STIs as well as chlamydia and gonorrhea NAAT results. A total of 4923 men were screened for chlamydia and gonorrhea from these 5 militaries during April 2016 to October 2017. The combined prevalence of chlamydia and gonorrhea in these five militaries ranged from 2.3% in Burundi to 11.9% in Belize. These infections were not successfully identified by symptomology; for example, only 2% of cases in Belize reported symptoms. In three of the five countries there was no statistical association between symptoms and positive NAAT results. The majority of individuals with these infections (81% to 98%) would be undiagnosed and untreated using only symptomology. Therefore, using symptoms alone to diagnose cases of chlamydia and gonorrhea is not an effective way to control these infections. We propose that automated, cartridge-based NAATs, be considered for routine use in diagnosing those at risk for STIs.

HIV Prevention Efforts and Incidence of HIV in Uganda.

BACKGROUND: To assess the effect of a combination strategy for prevention of human immunodeficiency virus (HIV) on the incidence of HIV infection, we analyzed the association between the incidence of HIV and the scale-up of antiretroviral therapy (ART) and medical male circumcision in Rakai, Uganda. Changes in population-level viral-load suppression and sexual behaviors were also examined. METHODS: Between 1999 and 2016, data were collected from 30 communities with the use of 12 surveys in the Rakai Community Cohort Study, an open, population-based cohort of persons 15 to 49 years of age. We assessed trends in the incidence of HIV on the basis of observed seroconversion data, participant-reported use of ART, participant-reported male circumcision, viral-load suppression, and sexual behaviors. RESULTS: In total, 33,937 study participants contributed 103,011 person-visits. A total of 17,870 persons who were initially HIV-negative were followed for 94,427 person-years; among these persons, 931 seroconversions were observed. ART was introduced in 2004, and by 2016, ART coverage was 69% (72% among women vs. 61% among men, P<0.001). HIV viral-load suppression among all HIV-positive persons increased from 42% in 2009 to 75% by 2016 (P<0.001). Male circumcision coverage increased from 15% in 1999 to 59% by 2016 (P<0.001). The percentage of adolescents 15 to 19 years of age who reported never having initiated sex (i.e., delayed sexual debut) increased from 30% in 1999 to 55% in 2016 (P<0.001). By 2016, the mean incidence of HIV infection had declined by 42% relative to the period before 2006 (i.e., before the scale-up of the combination strategy for HIV prevention) - from 1.17 cases per 100 person-years to 0.66 cases per 100 person-years (adjusted incidence rate ratio, 0.58; 95% confidence interval [CI], 0.45 to 0.76); declines were greater among men (adjusted incidence rate ratio, 0.46; 95% CI, 0.29 to 0.73) than among women (adjusted incidence rate ratio, 0.68; 95% CI, 0.50 to 0.94). CONCLUSIONS: In this longitudinal study, the incidence of HIV infection declined significantly with the scale-up of a combination strategy for HIV prevention, which provides empirical evidence that interventions for HIV prevention can have a population-level effect. However, additional efforts are needed to overcome disparities according to sex and to achieve greater reductions in the incidence of HIV infection. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Notes from the Field: Rift Valley Fever Response - Kabale District, Uganda, March 2016.

On March 9, 2016, a male butcher from Kabale District, Uganda, aged 45 years, reported to the Kabale Regional Referral Hospital with fever, fatigue, and headache associated with black tarry stools and bleeding from the nose. One day later, a student aged 16 years from a different sub-county in Kabale District developed similar symptoms and was admitted to the same hospital. The student also had a history of contact with livestock. Blood specimens collected from both patients were sent for testing for Marburg virus disease, Ebola virus disease, Rift Valley fever (RVF), and Crimean Congo Hemorrhagic fever at the Uganda Virus Research Institute, as part of the viral hemorrhagic fevers surveillance program. The Uganda Virus Research Institute serves as the national viral hemorrhagic fever reference laboratory and hosts the national surveillance program for viral hemorrhagic fevers, in collaboration with the CDC Viral Special Pathogens Branch and the Uganda Ministry of Health.

The global burden of viral hepatitis from 1990 to 2013: findings from the Global Burden of Disease Study 2013.

BACKGROUND: With recent improvements in vaccines and treatments against viral hepatitis, an improved understanding of the burden of viral hepatitis is needed to inform global intervention strategies. We used data from the Global Burden of Disease (GBD) Study to estimate morbidity and mortality for acute viral hepatitis, and for cirrhosis and liver cancer caused by viral hepatitis, by age, sex, and country from 1990 to 2013. METHODS: We estimated mortality using natural history models for acute hepatitis infections and GBD's cause-of-death ensemble model for cirrhosis and liver cancer. We used meta-regression to estimate total cirrhosis and total liver cancer prevalence, as well as the proportion of cirrhosis and liver cancer attributable to each cause. We then estimated cause-specific prevalence as the product of the total prevalence and the proportion attributable to a specific cause. Disability-adjusted life-years (DALYs) were calculated as the sum of years of life lost (YLLs) and years lived with disability (YLDs). FINDINGS: Between 1990 and 2013, global viral hepatitis deaths increased from 0·89 million (95% uncertainty interval [UI] 0·86-0·94) to 1·45 million (1·38-1·54); YLLs from 31·0 million (29·6-32·6) to 41·6 million (39·1-44·7); YLDs from 0·65 million (0·45-0·89) to 0·87 million (0·61-1·18); and DALYs from 31·7 million (30·2-33·3) to 42·5 million (39·9-45·6). In 2013, viral hepatitis was the seventh (95% UI seventh to eighth) leading cause of death worldwide, compared with tenth (tenth to 12th) in 1990. INTERPRETATION: Viral hepatitis is a leading cause of death and disability worldwide. Unlike most communicable diseases, the absolute burden and relative rank of viral hepatitis increased between 1990 and 2013. The enormous health loss attributable to viral hepatitis, and the availability of effective vaccines and treatments, suggests an important opportunity to improve public health. FUNDING: Bill & Melinda Gates Foundation.

Global epidemiology of hepatitis C virus infection: new estimates of age-specific antibody to HCV seroprevalence.

UNLABELLED: In efforts to inform public health decision makers, the Global Burden of Diseases, Injuries, and Risk Factors 2010 (GBD2010) Study aims to estimate the burden of disease using available parameters. This study was conducted to collect and analyze available prevalence data to be used for estimating the hepatitis C virus (HCV) burden of disease. In this systematic review, antibody to HCV (anti-HCV) seroprevalence data from 232 articles were pooled to estimate age-specific seroprevalence curves in 1990 and 2005, and to produce age-standardized prevalence estimates for each of 21 GBD regions using a model-based meta-analysis. This review finds that globally the prevalence and number of people with anti-HCV has increased from 2.3% (95% uncertainty interval [UI]: 2.1%-2.5%) to 2.8% (95% UI: 2.6%-3.1%) and >122 million to >185 million between 1990 and 2005. Central and East Asia and North Africa/Middle East are estimated to have high prevalence (>3.5%); South and Southeast Asia, sub-Saharan Africa, Andean, Central, and Southern Latin America, Caribbean, Oceania, Australasia, and Central, Eastern, and Western Europe have moderate prevalence (1.5%-3.5%); whereas Asia Pacific, Tropical Latin America, and North America have low prevalence (<1.5%). CONCLUSION: The high prevalence of global HCV infection necessitates renewed efforts in primary prevention, including vaccine development, as well as new approaches to secondary and tertiary prevention to reduce the burden of chronic liver disease and to improve survival for those who already have evidence of liver disease.

Control of viral hepatitis infection in Africa: are we dreaming?

BACKGROUND: At least five different types of viral hepatitis cause problems of significant public health importance in Africa, where together they constitute a huge burden of disease. But until now, efforts to control the infections have been largely piecemeal. Analysis of the strategies needed to control each virus, however, reveals major overlaps. PROPOSAL: We propose that the control of these infections in the WHO African Region should start with the common strategies rather than with each disease. But this approach presents potentially huge problems to overcome, such as the difficulty of integrating multiple health service elements - the track record for successful integration of such services is not good. This is despite encouraging rhetoric from donors and national leaders alike. And to succeed, disparate programmes must work closely together. But we believe that the time is right to create new opportunities for prevention and treatment of hepatitis, including increasing education, and promoting screening and treatment for more than 500 million people already infected with hepatitis B and C viruses. IMPACT: The impact of these efforts on decreasing mortality and morbidity will be significant because of the high burden of disease from these infections, and also because the effect will spill over to benefit the control of other communicable diseases and health systems strengthening. Such a project will inevitably involve multiple strategies that will vary somewhat according to the epidemiology of the diseases and the location.

The risk of perinatal hepatitis B virus transmission: hepatitis B e antigen (HBeAg) prevalence estimates for all world regions.

BACKGROUND: HBeAg presence in childbearing-age women is a major determinant of perinatal hepatitis B virus (HBV) transmission. The risk of developing chronic HBV infection and liver disease is highest at young age. Our aim was to assess perinatal HBV transmission risk by means of estimating age- and region-specific HBeAg prevalence. METHODS: Based on observed HBeAg seroprevalence data obtained from a systematic literature review, we modeled HBeAg prevalence using an empirical Bayesian hierarchical model. Age- and region-specific estimates were generated for 1990 and 2005. RESULTS: Globally, highest HBeAg prevalence of over 50 % was found in 0-9 years old girls. At reproductive age, HBeAg prevalence was 20-50 %. Prevalence was highest in young females in East Asia in 1990 (78 %), the infection was less common in Sub-Saharan and North Africa. Regional differences in prevalence were smaller in 2005. There was an overall decrease in HBeAg between 1990 and 2005, which was strongest among girls in Oceania (23.3 % decline), South and South-East Asia (14 % decline). However, in these regions, prevalence remained high at 67 % among young females in 2005. Smaller decreases were observed in women at reproductive age, at which 24-32 % of all HBsAg-positive women were HBeAg-positive in 2005, with lowest prevalence in Southern Sub-Saharan Africa and highest prevalence in Oceania and South-East Asia. CONCLUSIONS: HBeAg estimates are crucial for understanding the epidemiology of HBV and for prioritizing implementation of WHO`s prevention recommendations for all infants to receive the first dose of hepatitis B vaccine within 24 hours of birth. Results will have importance as access to treatment for chronic HBV infection is expanded.

Long-term protective effects of hepatitis A vaccines. A systematic review.

OBJECTIVE: Data on duration and long-term protective effects of hepatitis A vaccines (HepA) have not been reviewed using a systematic approach. Our objective is to provide a comprehensive review of evidence on the duration of protection achieved by HepA, which is needed for revising existing vaccine policies. Limitations in data availability and implications for future research in this area are discussed. METHODS: A systematic literature review was conducted including all studies published between 1997 and 2011 reporting on long-term protection of HepA. The outcomes considered were hepatitis A virus (HAV) infection and sero-protection measured by anti-HAV antibodies after follow-up times of over 5 years post-vaccination. RESULTS: 299 studies were identified from MEDLINE and 51 studies from EMBASE. 13 manuscripts met our inclusion criteria. The maximum observation times and reported persistence levels of sero-protective anti-HAV antibodies was 15 years for live attenuated HepA and 14 years for inactivated HepA. All data were from observational studies and showed that higher number of doses of live attenuated vaccine led to higher seropositivity and GMT, but dosage and schedule did not significantly impact the long-term protection following inactivated vaccine. Few comparisons were made between the two vaccine types indicating highest levels of antibody titers achieved by multiple doses of live attenuated vaccines 7 years post-vaccination. CONCLUSION: Available data indicate that both inactivated and live attenuated HepA are capable of providing protection up to 15 years as defined by currently accepted, conservative correlates of protection. Further investigations are needed to continue to monitor the long-term protection afforded by these vaccines. Standardized methods are required for vaccine-follow-up studies including assessment of co-variables potentially affecting long-term protection.

The global burden of hepatitis E virus genotypes 1 and 2 in 2005.

UNLABELLED: We estimated the global burden of hepatitis E virus (HEV) genotypes 1 and 2 in 2005. HEV is an emergent waterborne infection that causes source-originated epidemics of acute disease with a case fatality rate thought to vary by age and pregnancy status. To create our estimates, we modeled the annual disease burden of HEV genotypes 1 and 2 for 9 of 21 regions defined for the Global Burden of Diseases, Injuries, and Risk Factors Study (the GBD 2010 Study), which represent 71% of the world's population. We estimated the seroprevalence of anti-HEV antibody and annual incidence of infection for each region using data from 37 published national studies and the DISMOD 3, a generic disease model designed for the GBD Study. We converted incident infections into three mutually exclusive results of infection: (1) asymptomatic episodes, (2) symptomatic disease, and (3) death from HEV. We also estimated incremental cases of stillbirths among infected pregnant women. For 2005, we estimated 20.1 (95% credible interval [Cr.I.]: 2.8-37.0) million incident HEV infections across the nine GBD Regions, resulting in 3.4 (95% Cr.I.: 0.5-6.5) million symptomatic cases, 70,000 (95% Cr.I.: 12,400-132,732) deaths, and 3,000 (95% Cr.I.: 1,892-4,424) stillbirths. We estimated a probability of symptomatic illness given infection of 0.198 (95% Cr.I.: 0.167-0.229) and a probability of death given symptomatic illness of 0.019 (95% Cr.I.: 0.017-0.021) for nonpregnant cases and 0.198 (95% Cr.I.: 0.169-0.227) for pregnant cases. CONCLUSION: The model was most sensitive to estimates of age-specific incidence of HEV disease.

Challenges to mapping the health risk of hepatitis A virus infection.

BACKGROUND: World maps are among the most effective ways to convey public health messages such as recommended vaccinations, but creating a useful and valid map requires careful deliberation. The changing epidemiology of hepatitis A virus (HAV) in many world regions heightens the need for up-to-date risk maps. HAV infection is usually asymptomatic in children, so low-income areas with high incidence rates usually have a low burden of disease. In higher-income areas, many adults remain susceptible to the virus and, if infected, often experience severe disease. RESULTS: Several challenges associated with presenting hepatitis A risk using maps were identified, including the need to decide whether prior infection or continued susceptibility more aptly indicates risk, whether to display incidence or prevalence, how to distinguish between different levels of risk, how to display changes in risk over time, how to present complex information to target audiences, and how to handle missing or obsolete data. CONCLUSION: For future maps to be comparable across place and time, we propose the use of the age at midpoint of population susceptibility as a standard indicator for the level of hepatitis A endemicity within a world region. We also call for the creation of an accessible active database for population-based age-specific HAV seroprevalence and incidence studies. Health risk maps for other conditions with rapidly changing epidemiology would benefit from similar strategies.

Treatment of chronic hepatitis B virus infection in resource-constrained settings: expert panel consensus.

Most of the estimated 350 million people with chronic hepatitis B virus (HBV) infection live in resource-constrained settings. Up to 25% of those persons will die prematurely of hepatocellular carcinoma (HCC) or cirrhosis. Universal hepatitis B immunization programmes that target infants will have an impact on HBV-related deaths several decades after their introduction. Antiviral agents active against HBV are available; treatment of HBV infection in those who need it has been shown to reduce the risk of HCC and death. It is estimated that 20-30% of persons with HBV infection could benefit from treatment. However, drugs active against HBV are not widely available or utilized in persons infected with HBV. Currently recommended antiviral agents used for treatment of human immunodeficiency virus (HIV) infection do not adequately suppress HBV, which is of great concern for the estimated 10% of the HIV-infected persons in Africa who are co-infected with HBV. Progressive liver disease has been shown to occur in co-infected persons whose HBV infection is not suppressed. In view of these concerns, an informal World Health Organization consultation of experts concluded that: chronic HBV is a major public health problem in emerging nations; all HIV-infected persons should be screened for HBV infection; HIV/HBV co-infected persons should be treated with therapies active against both viruses and that reduce the risk of resistance; standards for the management of chronic HBV infection should be adapted to resource-constrained settings. In addition, a research agendum was developed focusing on issues related to prevention and treatment of chronic HBV in resource-constrained settings.

Hepatitis A virus seroprevalence by age and world region, 1990 and 2005.

OBJECTIVE: To estimate current age-specific rates of immunity to hepatitis A virus (HAV) in world regions by conducting a systematic review and meta-analysis of published data. The estimation of the global burden of hepatitis A and policies for public health control are dependent on an understanding of the changing epidemiology of this viral infection. METHODS: Age-specific IgG anti-HAV seroprevalence data from more than 500 published articles were pooled and used to fit estimated age-seroprevalence curves in 1990 and 2005 for each of 21 world regions (as defined by the Global Burden of Disease 2010 Study). FINDINGS: High-income regions (Western Europe, Australia, New Zealand, Canada, the United States, Japan, the Republic of Korea, and Singapore) have very low HAV endemicity levels and a high proportion of susceptible adults, low-income regions (sub-Saharan Africa and parts of South Asia) have high endemicity levels and almost no susceptible adolescents and adults, and most middle-income regions have a mix of intermediate and low endemicity levels. CONCLUSION: Anti-HAV prevalence estimates in this analysis suggest that middle-income regions in Asia, Latin America, Eastern Europe, and the Middle East currently have an intermediate or low level of endemicity. The countries in these regions may have an increasing burden of disease from hepatitis A, and may benefit from new or expanded vaccination programs.

Florida Epidemic Intelligence Service Program: the first five years, 2001-2006.

The Florida Epidemic Intelligence Service Program was created in 2001 to increase epidemiologic capacity within the state. Patterned after applied epidemiology training programs such as the Centers for Disease Control and Prevention Epidemic Intelligence Service and the California Epidemiologic Investigation Service, the two-year postgraduate program is designed to train public leaders of the future. The long-term goal is to increase the capacity of the Florida Department of Health to respond to new challenges in disease control and prevention. Placement is with experienced epidemiologists in county health departments/consortia. Fellows participate in didactic and experiential components, and complete core activities for learning as evidence of competency. As evidenced by graduate employment, the program is successfully meeting its goal. As of 2006, three classes (n=18) have graduated. Among graduates, 83% are employed as epidemiologists, 67% in Florida. Training in local health departments and an emphasis on graduate retention may assist states in strengthening their epidemiologic capacity.

Impact of the universal hepatitis B immunization program in Mongolia: achievements and challenges.

BACKGROUND: The impact of the universal infant hepatitis B (HB) immunization program initiated in 1991 in Mongolia is still unclear. METHODS: A nationwide school-based cross-sectional serosurvey was conducted in 2004, with stratified, multistage, random cluster sampling from all public elementary schools (n=593) in Mongolia. All children were tested for serological markers of hepatitis B virus (HBV). RESULTS: Serology results were available for 1,145 children (592 boys and 553 girls) aged 7-12 years (survey response rate: 93%). Immunization card was available for 702 (61.3%) children. The coverage of complete HB vaccination was 60.1% and it was increased by birth cohort from 44% to 76%. Significantly higher proportion of children in Metropolitan cities (75.2%) was completely vaccinated with HB compared to those in Province centers (55.7%) and rural areas (59.1%). HBV infection occurred in 5.9%, 13.2%, and 20.8% of complete vaccinees living in Metropolitan, Province centers, and rural areas, respectively; of whom 1.2%, 2.9%, and 8.6% were HB surface antigen (HBsAg) carriers, respectively. Only 17.0% of the children had protective anti-HBs which decreased from 31.1% to 16.3% among 7 to 12-year-olds indicating its decay with time. CONCLUSIONS: Prevalence of HBV infection and carriage among young generation meaningfully declined compared with those of previous studies in Mongolia. The coverage of birth dose and complete HB vaccination was significantly low in Province centers and rural areas which should be taken into consideration.

Administration of hepatitis B vaccine in winter as a significant predictor of the poor effectiveness of vaccination in rural Mongolia: evidence from a nationwide survey.

BACKGROUND: Universal hepatitis B (HB) immunisation is the most effective means for prevention of hepatitis B virus (HBV) infection worldwide. Maintaining the vaccine cold chain is an essential part of a successful immunisation programme. Our recent nationwide survey in Mongolia has observed significant urban-rural differences in the prevalence of HBV infection among vaccinated cohorts. OBJECTIVE: To examine whether the administration of HB vaccine in winter contributes to these residential discrepancies on the effectiveness of vaccination. DESIGN AND SETTING: In 2004, a nationwide serosurvey was carried out covering both urban and rural areas of Mongolia. Sampling was multistage, with random probability from all public schools in the country. PARTICIPANTS: A random sample of 1145 children (51.7% boys; aged 7-12 years), representative of Mongolian elementary school children. RESULTS: Multivariate logistic regression analysis identified that total (past and current) HBV infection (OR 2.31, 95% CI 1.20 to 4.42; p = 0.012) was independently associated with the administration of all HB vaccines in winter. An increased OR for current HBV infection was also observed (OR 2.58, 95% CI 0.87 to 7.68; p = 0.089), but without significance. Interestingly, after stratifying by residence, the association between winter vaccination and total HBV infection was evident for rural (p = 0.008) but not for urban areas (p = 0.294). The frequency of vaccine-induced immunity was significantly (p = 0.007) lower for those who received HB vaccine at birth during winter in rural areas. CONCLUSION: Administration of HB vaccine during winter is an important predictor of the low effectiveness of vaccination in rural Mongolia. To improve the effectiveness of HB vaccination in remote areas, cold chain control should be addressed with particular attention to the winter season.

Seroepidemiology of hepatitis B virus infection among children in Mongolia: results of a nationwide survey.

BACKGROUND: Because Mongolia is one of the highly endemic countries for hepatitis B virus (HBV) infection in the world, hepatitis B (HB) vaccine was introduced into the National Expanded Program on Immunization in 1991. However, relatively few data are available concerning HBV infection among children born after the start of the program, so far. The aim of the present paper was to describe the seroepidemiology of HBV infection among primary school children using representative national data. METHODS: In 2004, a nationwide school-based cross-sectional serosurvey was carried out throughout Mongolia, covering both urban and rural areas. Serum samples were tested for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc) and hepatitis B e antigen (HBeAg) as well as for liver enzymes. RESULTS: A total of 1145 children aged 7-12 years were studied, which represents nearly 2% of the second grade population of elementary schools in Mongolia. The overall prevalence of HBsAg and anti-HBc was 5.2% (95% confidence interval [CI]: 3.9-6.5%) and 15.6% (95%CI: 13.5-17.7%), respectively. Among HBsAg-positive children 67.8% (95%CI: 55.9-79.7%) were also positive for HBeAg. The prevalence of chronic HBV infection increased by age and was significantly higher among children from rural areas compared to those from urban areas (7.7% vs 3.0%; P < 0.001). In the multivariate logistic regression analysis, rural residence (odds ratio [OR]: 2.57; 95%CI: 1.45-4.58), male sex (OR: 1.9; 95%CI: 1.08-3.26) and age (OR: 1.5; 95%CI: 1.10-2.05) were independent demographic predictors for chronic HBV infection. CONCLUSIONS: The prevalence of chronic HBV infection has been decreasing in the Mongolian young generation, most likely due to infant HB vaccination. However, significant rural-urban differences in the prevalence of HBV infection were found that demand further investigation to estimate the potential causes.