Seroprevalence of hepatitis C virus infection and its association with natural infection of hepatitis B virus among preschool children in Taiwan

Taiwan is a hyperendemic area of hepatitis B virus (HBV) infection where chronic hepatitis B is the most important cause of liver cirrhosis and hepatoma. Since, diagnostic kit for detecting hepatitis C virus (HCV) infection has been developed, HCV was found to be another important etiology of chronic liver disease. In order to study the seroprevalence of HCV infection among preschool children after mass hepatitis B vaccination program in Taiwan, a community-based survey was carried out in 54 kindergartens in 10 urban areas, 10 rural areas, and two aboriginal areas randomly selected through stratified sampling. Serum specimens of 2538 preschool children were screened for the HCV antibodies (anti-HCV) by a commercially available third-generation microparticle enzyme immunoassay and for HBV markers by radioimmunoassay methods. The multivariate-adjusted odd ratios (OR_m) with their 95% confidence intervals (CI) were estimated through the multiple logistic regression analysis. A total of 58 children were anti-HCV seropositive, giving a prevalence of 2.3%. The prevalence of anti-HCV was 1.0% (5 of 484) among aboriginal children, a significantly decreased seroprevalence compared with those among other ethnic groups after multivariate adjustment. Boys had a higher anti-HCV seroprevalence, but not statistically significantly different from girls (OR_m: 1.6; 95% CI: 0.9–2.8; p = 0.08). The seroprevalence of the age group of 3–4 years was lower than that of the age group of 5–6 years (OR_m: 2.2; 95% CI: 1.1–4.2; p = 0.02). After multivariate adjustment, preschool children with natural HBV infection had a higher anti-HCV seroprevalence, but not statistically significantly different from those without natural HBV-infection (OR_m: 2.6; 95% CI: 0.9–7.4; p = 0.08 for HBV-infected vs. uninfected). HCV infection varies with gender, residential area, and natural HBV infection. HCV and HBV might share common transmission routes in Taiwan.     

张家港市人群乙型和丙型肝炎血清流行病学调查

目的了解张家港市人群乙型肝炎和丙型肝炎病毒的感染状况,建立有效的防治措施。方法采用随机整群抽样的方法调查1岁以上各年龄组人群,对每名对象进行问卷调查,并采集血清检测HBsAg、抗-HBs和抗-HCV。结果张家港市人群HBsAg、抗-HBs和抗-HCV阳性率分别为5.15%、52.69%、0.31%。1~19岁组人群HBsAg阳性率为0.99%,20岁以上组人群阳性率为5.95%。男性HBsAg阳性率高于女性。有免疫史的人群HBsAg阳性率明显低于未免疫者和免疫史不详者。抗-HCV阳性率与年龄、性别无关。使用血制品的人群抗-HCV阳性率最高。结论乙肝疫苗纳入儿童免疫规划效果显著,需进一步做好成人乙肝疫苗接种工作;使用血制品仍是丙肝病毒感染的重要途径,其他传播途径也不可忽视。     

Decrease in the prevalence of hepatitis B and a low prevalence of hepatitis C virus infections in the general population of the Seychelles

A serological survey of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections was carried out on a random sex- and age-stratified sample of 1006 individuals aged 25-64 years in the Seychelles islands. Anti-HBc and anti-HCV antibodies were detected using commercially available enzyme-linked immunosorbent assays (ELISA), followed by a Western blot assay in the case of a positive result for anti-HCV. The age-adjusted seroprevalence of anti-HBc antibodies was 8.0% (95% CI: 6.5-9.9%) and the percentage prevalence among males/females increased from 7.0/3.1 to 19.1/13.4 in the age groups 25-34 to 55-64 years, respectively. Two men and three women were positive for anti-HCV antibodies, with an age-adjusted seroprevalence of 0.34% (95% CI: 0.1-0.8%). Two out of these five subjects who were positive for anti-HCV also had anti-HBc antibodies. The seroprevalence of anti-HBc was significantly higher in unskilled workers, persons with low education, and heavy drinkers. The age-specific seroprevalence of anti-HBc in this population-based survey, which was conducted in 1994, was approximately three times lower than in a previous patient-based survey carried out in 1979. Although there are methodological differences between the two surveys, it is likely that the substantial decrease in anti-HBc prevalence during the last 15 years may be due to significant socioeconomic development and the systematic screening of blood donors since 1981. Because hepatitis C virus infections are serious and the cost of treatment is high, the fact that the prevalence of anti-HCV antibodies is at present low should not be an argument for not screening blood donors for anti-HCV and eliminating those who are positive.     

深圳市某区学龄前儿童丙型肝炎血清流行病学调查

目的:C型肝炎目前并未有疫苗预防接种,因此对C型肝炎的流行情况、尤其是C型肝炎病毒的致病机转及感染途径方面的探讨,以其切断感染源,是为迫切需要。方法:以多步骤抽样法在区、街道中心与郊乡地区筛检54所幼儿园。从静脉采血取得血清,以自动化仪器测试肝功能指针研究数据,以SPSS软件系统做统计分析。结果:有19位儿童为C型肝炎抗体阳性,占2.3%。男孩的C型肝炎抗体流行率比女孩高,但经统计学处理无显著差异(ORm:1.6;95%CI:0.9～2.8;P=0.08)。3～4岁年龄段的流行率比5～6岁低(ORm:2.2;95%CI:1.1～4.2;P=0.02)。经多变项调整分析后,具C型肝炎抗体流行率的儿童且受B型肝炎病毒自然感染的比未被感染的高,但经统计学处理无显著差异(ORm:2.6;95%CI:0.9～7.4;P=0.08 for HBV-infected vs.uninfected)。结论:在龙岗区,C型肝炎病毒的感染与B型肝炎病毒自然的感染,除了性别与居住地外,应该还有更多的共同传染途径存在。另外,为数不少的居民相信药物注射比口服治疗快,尤其是对儿童的治疗,因此间接造成C型肝炎病毒感染的数量增加。     

Seroprevalence of hepatitis B and C viral co-infections among children infected with human immunodeficiency virus attending the paediatric HIV care and treatment center at Muhimbili National Hospital in Dar-es-Salaam,Tanzania

Background  

With increased availability of antibiotics and antifungal agents hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are becoming a cause for significant concern in HIV infected children. We determined the seroprevalence and risk factors for HBV and HCV among HIV infected children aged 18 months to 17 years, attending the Paediatric HIV Care and Treatment Center (CTC) at Muhimbili National Hospital (MNH) in Dar-es-Salaam, Tanzania.     

Determinants of Hepatitis B Virus (HBV) Infection Among University Students in Central Bangladesh

This study aimed to determine the seroprevalence and determinants of hepatitis B virus (HBV) infection among university students in Bangladesh. This cross-sectional study was conducted among 614 students from five universities in central Bangladesh. Data were collected on demographic information, immunization history, medical and blood transfusion history through the face-to-face interview. Blood samples were collected and screened for anti-HBsAg using ELISA, HBsAg Rapid Test-cassette, and immune chromatographic test. The overall seroprevalence of HBV infection was 5.0%, and vaccination coverage was 19.2% among the participants. Students having a history of surgery (OR 11.004, 95% CI 3.211–37.707), blood transfusion (OR 5.651, 95% CI 0.965–33.068), being married (OR 4.776, 95% CI 1.508–15.127), and not being vaccinated (OR 9.825, 95% CI 1.130–85.367) were at higher risk of being infected by HBV. This study showed the endemicity of HBV infection among the Bangladeshi population. Marriage, surgical or blood transfusion history, not being vaccinated were the determinants of HBV infection within the study population. Public health initiatives for preventing HBV infection at the university levels should be envisaged.

     

The relationships of chronic hepatitis and cirrhosis to alcohol intake,hepatitis B and C,and delta virus infection: a case-control study in Albania.

The present study examined the effect of hepatitis B virus (HBV) and alcohol intake, and the role of hepatitis delta virus (HDV) and hepatitis C virus (HCV) in the aetiology of chronic liver disease in Albania. A total of 106 cases of liver cirrhosis or chronic hepatitis were compared to 195 control patients without these or other liver diseases. Adjusted odds ratios were 52.7 (95% CI 22.7-122) for HBV surface antigen, 26.9 (95% CI 4.9-147) for anti-HCV, 26.2 (95% CI 3-1-221) for anti-HDV, 2.4 (95% CI 1.3-4.4) for lifetime alcohol intake and 2.3 (95% CI 1-5.5) for duration of alcohol intake. Although not significant, an interaction was suggested between HBsAg and anti-HCV and between HBsAg and alcohol intake. Our study underlines the role of hepatitis viruses in the development of chronic liver diseases. Additionally, it suggests that heavy alcohol intake may magnify the effect of HBV on these diseases. HBV vaccination and alcohol abstention appear to be important strategies to reduce the risk of liver cirrhosis and chronic hepatitis in Albania.     

Seroepidemiology of hepatitis A and hepatitis B virus in Luxembourg

A prospective seroepidemiological survey was carried out in Luxembourg in 2000-2001 to determine the antibody status of the Luxembourg population against hepatitis A virus (HAV) and hepatitis B virus (HBV). One of the objectives of this survey was to assess the impact of the hepatitis B vaccination programme, which started in May 1996 and included a catch-up campaign for all adolescents aged 12-15 years. Venous blood from 2679 individuals was screened for the presence of antibodies to HAV antigen and antibodies to hepatitis B surface antigen (anti-HBs) using an enzyme immunoassay. Samples positive for anti-HBs were tested for antibody to hepatitis B core antigen (anti-HBc) using a chemiluminiscent microparticle immunoassay to distinguish between individuals with past exposure to vaccine or natural infection. The estimated age-standardized anti-HAV seroprevalence was 42.0% [95% confidence interval (CI) 39.8-44.1] in the population >4 years of age. Seroprevalence was age-dependent and highest in adult immigrants from Portugal and the former Yugoslavia. The age-standardized prevalence of anti-HBs and anti-HBc was estimated at 19.7% (95% CI 18.1-21.3) and 3.16% (95% CI 2.2-4.1) respectively. Anti-HBs seroprevalence exceeding 50% was found in the cohorts targeted by the routine hepatitis B vaccination programme, which started in 1996. Our study illustrates that most young people in Luxembourg are susceptible to HAV infection and that the hepatitis B vaccination programme is having a substantial impact on population immunity in children and teenagers.     

Clinical course and consequences of hepatitis B infection

Hepatitis B virus (HBV) is a small enveloped virus containing partially double-stranded DNA. The DNA and HBV-specific DNA polymerase are surrounded by the HBV core antigen (HBcAg), which in turn is surrounded by a lipoprotein envelope containing the HBV surface antigen (HBsAg). Serum of HBV-infected patients contains complete virus particles, as well as non-infectious spherical or filamentous HBsAg particles. Acute hepatitis is characterized by the appearance of serum HBV markers, including HBsAg and IgM anti-HBc, which then disappear during convalescence. Persistence of HBsAg for more than 6 months indicates a carrier state. Chronic hepatitis develops in 90% of newborns who become infected, compared with 29-40% of children infected and 5-10% of adults infected. The immune status of the infected person also influences the development of chronic hepatitis. Chronic HBV infection can be diagnosed by serology (identification of HBsAg and HBV DNA), biochemistry (elevated aminotransferase levels) and liver biopsy. The last is important to assess the severity of disease, its stage and prognosis, and to exclude other hepatic diseases. The outcome of chronic HBV infection varies between individuals, with estimated 5-year survivals of 97% for chronic persistent hepatitis, 86% for chronic active hepatitis, and 55% for chronic active hepatitis with cirrhosis. Treatment with interferon alpha is effective in up to 40% of cases, but in view of the very large number of infected people worldwide, vaccination to prevent spread of the disease is a more cost-effective option.     

Hepatitis B,C, and D Virus Infections and AFP Tumor Marker Prevalence Among the Elderly Population in Mongolia: A Nationwide Survey

ObjectivesInfections with hepatitis B, C, and D virus (HBV, HCV, and HDV) are a major public health problem and lead to serious complications such as cirrhosis and hepatocellular carcinoma. We aimed to determine the seroprevalence of hepatitis B surface antigen (HBsAg), anti-HCV, anti-HDV immunoglobulin G, alpha-fetoprotein (AFP), and dual and triple hepatitis virus infections in Mongolia.MethodsA total of 2313 participants from urban and rural regions were randomly recruited for this cross-sectional study. A questionnaire was used to identify the risk factors for hepatitis virus infections, and the seromarkers were measured using immunoassay kits.ResultsAmong all participants, the prevalence of HBV, HCV, and HDV was 15.6%, 36.6%, and 14.3%, respectively. The infection rates were significantly higher in females and participants with a lower education level, rural residence, older age, and a history of blood transfusion. HBV and HCV co-infection was found in 120 (5.2%) participants and HBV, HCV, and HDV triple infection was detected in 67 (2.9%) participants. The prevalence of elevated AFP was 2.7%, 5.5%, and 2.6% higher in participants who were seropositive for HBsAg (p=0.01), anti-HCV (p<0.001), and anti-HDV (p=0.022), respectively. Elevated AFP was more prevalent in participants co-infected with HBV and HCV (5.8%, p=0.023), HBV and HDV (6.0%, p<0.001), and triple-infected with HBV, HCV, and HDV (7.5%) than in uninfected individuals.ConclusionsNearly half (49.8%) of the study population aged ≥40 years were infected with HBV, HCV, or HDV, and 22.4% had dual or triple infections.     

Seroprevalence of HIV,hepatitis b,and hepatitis c among opioid drug users on methadone treatment in the netherlands

Background  

Injecting drug users (IDU) remain an important population at risk for blood-borne infections such as human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV). In the Netherlands, a program is being implemented to offer annual voluntary screening for these infections to opioid drug users (ODUs) screened in methadone care. At two care sites where the program is now operating, our study aimed to estimate the seroprevalence among ODUs screened for HIV, HBV and HCV; to evaluate HBV vaccination coverage; and to assess the feasibility of monitoring seroprevalence trends by using routine annual screening data.     

Seroprevalence for Hepatitis E and Other Viral Hepatitides among Diverse Populations,Malawi

Data on prevalence of hepatitis E virus (HEV) in Malawi is limited. We tested blood samples from HIV-uninfected and -infected populations of women and men enrolled in research studies in Malawi during 1989–2008 to determine the seroprevalence of HEV, hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV). Samples were tested for IgG against HEV, total antibodies against HAV and HCV, and presence of HBV surface antigens. Of 800 samples tested, 16.5% were positive for HEV IgG, 99.6% were positive for HAV antibodies, 7.5% were positive for HBV surface antigen, and 7.1% were positive for HCV antibodies. No clear trends over time were observed in the seroprevalence of HEV, and HIV status was not associated with hepatitis seroprevalence. These preliminary data suggest that the seroprevalence of HEV is high in Malawi; the clinical effects may be unrecognized or routinely misclassified.     

Heterosexual and homosexual transmission of hepatitis C virus: relation with hepatitis B virus and human immunodeficiency virus type 1.

A seroprevalence study was carried out on 1757 outpatients consecutively seen in a sexually transmitted disease (STD) clinic in order to evaluate the sexual transmission of hepatitis C virus (HCV). A total of 1442 consenting patients were tested for hepatitis C, hepatitis B and human immunodeficiency virus type 1 (HCV, HBV, HIV-1) antibodies. The relations between anti-HCV, anti-HBc and anti-HIV-1 were studied. Of 73 anti-HCV positive reactions, 45 (61.6%) were confirmed by the recombinant immunoblot assay (RIBA). The proportion of individuals with anti-HCV was higher in outpatients with a history of sexually transmitted disease than without. It was 2.8% in non drug user heterosexuals and 2.9% in non drug user homosexuals. Intravenous drug users (IDU) had higher anti-HCV prevalence when a history of STD was taken into account (42.3% in subjects with STD versus 36.7% in subjects without STD). Among non drug user heterosexuals an association was found between anti-HCV and anti-HBc. These data suggest that sexual transmission of HCV occurs, although it seems to be less efficient than other parenteral modes of transmission. When a more sensitive and specific marker of HCV infection become available, a more accurate estimate of the frequency and efficiency of the sexual transmission will be possible.     

Knowledge,attitudes, and practices regarding hepatitis B vaccination among hospital-based doctors and nurses in China: Results of a multi-site survey

BackgroundHepatitis B virus (HBV) can cause chronic HBV infection, which may lead to advanced cirrhosis and liver cancer. Healthcare workers (HCWs) are at risk HBV infection as an occupational hazard. Hepatitis B vaccination of HCWs is recommended by WHO, but the status of hepatitis B vaccination among HCWs in China is seldom reported.MethodologyWe conducted a cross-sectional study in 22 hospitals of 3 developed cities in China. We interviewed managers in infectious diseases and occupational health departments, and at least 40 HCWs per hospital.ResultsWe interviewed 929 HCWs; 80.8% were vaccinated against hepatitis B and 96.7% were willing to be vaccinated; 38.2% of HCWs reported having at least one needle stick or sharps injury. Three hospitals provide free hepatitis B vaccination for HCWs; hospitals with a hepatitis B vaccination policy, more HCWs reported being vaccinated (91.7% vs 79.0%, P < 0.001). HCWs in high risk departments (P = 0.011), with more knowledge of hepatitis B vaccine (P < 0.001), and with fewer working years (P = 0.002) were more likely to be vaccinated against HBV. Infectious diseases and occupational health managers had positive attitudes towards hepatitis B vaccination.ConclusionsHepatitis B vaccination was well accepted among HCWs. Hospital provision of free vaccine, greater HCW knowledge of HBV, and working in higher-risk settings were associated with being vaccinated. A national policy of offering hepatitis B vaccine to HCWs should be considered in China. Provision of free hepatitis B vaccine for HBsAb negative HCWs may be acceptable. Education about HBV and hepatitis B vaccine may help promote policy implementation.     

Sero-epidemiology of hepatitis B infection in an urban paediatric population in Turkey

The hepatitis B virus (HBV) seroprevalence rate is known to be 25-60% in Turkey with the highest prevalence in the east and south-east. There are insufficient data on sero-epidemiology of HBV infection in children living in East Turkey. The objective of this study was to estimate the seroprevalence of HBV infection in 6-17 year olds living in the largest city in East Turkey, and to correlate the serological results with epidemiological data. A total of 1091 serum samples were tested for hepatititis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs) and antibody to hepatitis B core antigen (anti-HBc) using a commercially available enzyme-linked immunosorbent assay. The overall seroprevalence rate was 9.7% and was correlated with age (P = 0.011). No statistical difference was detected between subjects with or without risk factors (P = 0.77). The seroprevalence of HBsAg was 1.8%, and it was higher in children with a low socio-economic status (P = 0.047). The educational status of the parents and sibling size did not affect the rate of total seroprevalence or HBsAg seroprevalence. Although we found that the HBV seroprevalence rate in East Turkey was not as high as reported previously, we emphasize the importance of screening children in order to identify asymptomatic patients in Turkey until HBV infection is entirely eradicated with vaccination programmes.     

Chronic hepatitis B: Immunological profile and current therapeutic vaccines in clinical trials

More than 250 million people worldwide are chronically infected with hepatitis B virus (CHB), and over half a million die each year due to CHB-associated liver complications such as cirrhosis and hepatocellular carcinoma. The translation of immunological knowledge about CHB into therapeutic strategies aiming to a sustainable hepatitis B virus (HBV) clearance has been challenging. In recent years, however, the understanding on the immune effectors required to overcome chronicity has notably increased thanks to preclinical and clinical research. Therapeutic vaccination may prove to be useful for treating CHB patients when coupled with current antiviral agents and other immunomodulatory strategies. This review summarizes current data and future perspectives on therapeutic vaccination. Other treatment alternatives that could be combined with vaccines for a complete cure from hepatitis B virus infection are also discussed.     

武汉市HIV/AIDS病人合并乙肝、丙肝感染情况分析

目的 了解武汉市HIV/AIDS病人合并乙肝、丙肝感染情况及其相关因素。方法 在2010 - 2018年武汉市报告的确证HIV/AIDS病人中,选取其一般人口学特征、感染途径、HBsAg、AntiHCV检测结果等信息进行整理分析,采用多元logistic回归分析合并感染相关因素。结果 2010 - 2018年武汉市共报告HIV/AIDS病人5 128人,男4 630人（90.3%）,女498人（9.7%）。年龄范围14～89岁,年龄中位数33（25～48）岁。其中,HBsAg阳性率为9.4%（443人）,AntiHCV阳性率为3.3%（152人）,合并HIV、HBV、HCV三重感染率为0.3%（12人）。在HIV/AIDS病人中,本省人群感染乙肝的可能性是本市人群的1.317倍,已婚/同居以及离异/分居/丧偶者感染乙肝的可能性分别是未婚者的2.044、1.892倍（P＜0.05）。与2018年相比,2011 - 2013以及2015年报告的HIV/AIDS病人感染丙肝的可能性更高,经输血和静脉吸毒途径感染的HIV/AIDS病人感染丙肝的可能性分别是经性行为传播者的18.942倍、63.537倍（P＜0.05）。结论 武汉市HIV/AIDS病人合并乙肝、丙肝感染情况不容忽视,其感染乙肝、丙肝的相关因素并不相同,需积极进行评估。     

Hepatitis B and C infection: Is it a problem in Polish healthcare workers?

Objectives

Hepatitis B (HBV) and C viruses (HCV) are among the most frequent blood borne pathogens. According to WHO, 5% of healthcare workers (in central Europe), are exposed to at least one sharps injury contaminated with HBV per year, 1,7% — contaminated with HCV.

Aims

The aims of the study were to determine prevalence of HCV and HBV infections, vaccination efficacy against hepatitis B and usefulness of alanine aminotransferase (ALT) testing in prophylactic examinations in healthcare workers (HCWs).

Material and Methods

In a group of 520 healthcare workers, a survey, laboratory and serologic tests such as ALT, HBsAg, anti-HBs, anti-HBcT and anti-HCV were carried out.

Results

The study revealed a low rate of workers with presence of HBsAg and anti-HCV (1,2% and 0,8% respectively). Anti-HBcT was found in 99 subjects (19%) without a significant association with experiencing an occupational percutaneous injury. Being vaccinated against HBV was declared by 90% of the subjects. There was no relationship between ALT level rise and positive HBsAg, anti-HCV and anti-HBcT tests.

Conclusion

A seroprevalence of HBV and HCV markers in HCWs found in the study is low and similar to the one found in general population. Current or past hepatitis B infections were independent of needle stick injuries. Vaccination against HBV coverage, although found to be high, should improve to 100%. Occupational prophylactic medical examinations found performing ALT test (obligatory in Poland for HCWs) not helpful. It seems that determination of anti-HBcT and anti-HCV status would be essential in pre-employment medical examinations.     

Hepatitis vaccination among drug users

Hepatitis virus infections are traditionally a major health problem among drug users (DUs). Several factors may favor the rapid spread of hepatitis infection in this category of patients. HBV and HCV are easily transmitted through exposure to infected blood and body fluids. DUs often prepare and use drug solutions together. Many in the DU community are infected and this provides multiple opportunities for transmission to others. Many of these patients with chronic hepatitis virus infection are not aware of their infections and this facilitates the spread of the diseases. Viral hepatitis is not inevitable for DUs. Although multiple factors have prevented the development of vaccines for hepatitis C, both hepatitis A and hepatitis B can be prevented by immunization. The purpose of this overview is to summarize and discuss the hepatitis vaccination in this population.     

Hepatitis B Virus Infection: Epidemiology and Vaccination

Worldwide, two billion people have been infected with hepatitisB virus (HBV), 360 million have chronic infection, and 600,000die each year from HBV-related liver disease or hepatocellularcarcinoma. This comprehensive review of hepatitis B epidemiologyand vaccines focuses on definitive and influential studies andhighlights current trends, policies, and directions. HBV canbe transmitted vertically, through sexual or household contact,or by unsafe injections, but chronic infections acquired duringinfancy or childhood account for a disproportionately largeshare of worldwide morbidity and mortality. Vaccination againstHBV infection can be started at birth and provides long-termprotection against infection in more than 90% of healthy people.In the 1990s, many industrialized countries and a few less-developedcountries implemented universal hepatitis B immunization andexperienced measurable reductions in HBV-related disease. Forexample, in Taiwan, the prevalence of chronic infection in childrendeclined by more than 90%. Many resource-poor nations have recentlyinitiated universal hepatitis B immunization programs with assistancefrom the Global Alliance for Vaccines and Immunization. Furtherprogress towards the elimination of HBV transmission will requiresustainable vaccination programs with improved vaccination coverage,practical methods of measuring the impact of vaccination programs,and targeted vaccination efforts for communities at high riskof infection. hepatitis B • hepatitis B vaccines • hepatitis B virus • immunization programs