乙型肝炎母婴传播阻断成功儿童乙型肝炎病毒突破性感染的特征

目的了解乙型肝炎(乙肝)母婴传播阻断成功儿童乙肝病毒(HBV)突破性感染及其影响因素。方法选取江苏省淮安市淮安区2009年9月-2011年1月乙肝表面抗原(HBsAg)阳性母亲所生儿童,且乙肝母婴传播阻断成功。阻断成功定义为儿童按国家免疫程序在完成出生时乙肝疫苗(HepB)和乙肝免疫球蛋白以及1、6月龄HepB接种后7-12月龄HBsAg阴性,HBV突破性感染定义为阻断成功儿童在12月龄后HBsAg阳性或24月龄后乙肝核心抗体(HBcAb)阳性。至2019年9月进行5次随访并检测HBV血清标志物,分析HBV突破性感染及其影响因素。结果本研究共纳入儿童390名,其中12名29-117月龄儿童发生HBV突破性感染,发生率为3.08%(12/390),均为乙肝核心抗体(HBcAb)阳性和HBsAg阴性。乙肝疫苗(HepB)初次免疫无、低、正常、高应答儿童HBV突破性感染率分别为25.00%、6.67%、2.61%、0.95%;母亲HBeAg阳性、阴性的儿童分别为9.76%、0.00%;母亲高、低HBV病毒载量的儿童分别为11.96%、0.34%。儿童HBV突破性感染发生密度为0.36/100人年;多因素Cox回归分析显示,HepB初次免疫低或无应答、母亲高病毒载量是儿童HBV突破性感染的危险因素(HR=5.91,95%CI:1.87-18.71;HR=45.81,95%CI:5.88-356.96)。结论乙肝母婴传播阻断成功儿童的HBV突破性感染发生率较低;母亲HBeAg阳性、母亲高HBV病毒载量、HepB初次免疫低或无应答的儿童更易发生突破性感染。     

Hepatitis B virus infection in northern Uganda: Impact of pentavalent hepatitis B vaccination

Chronic hepatitis B virus infection (CHBI) is effectively prevented by vaccination starting at birth. Beginning in 2002 Uganda adopted a policy of providing the pentavalent hepatitis B vaccine starting at 6 weeks of age. However, there is concern that this delay may leave the infant vulnerable to infection during the first 6 weeks of life. We assessed whether vaccination at 6 weeks was an effective strategy by HBV serologic study. Of 656 persons tested for HBV, 9.4% were chronically infected; among children aged 5–9 years the prevalence was 7.6%. Of all tested, 73 were born (i.e., aged ≤4 years) after the introduction of the pentavalent vaccine; none were infected with HBV (p = 0.003). In this study, vaccination with the pentavalent vaccine at 6 weeks did not result in CHBI, but rather provides an opportunity to prevent mother-to-infant transmission of HBV infection where there is no access to birth-dose vaccine.     

Seroepidemiological study of hepatitis B virus markers in Japan

BackgroundIn Japan, since 1986, selective vaccination has been implemented as a hepatitis B prevention strategy. The target of vaccination is the infant born to a hepatitis B surface antigen (HBsAg)-positive mother. The current Japanese hepatitis B prevention strategy focuses on reducing the number of HBV carriers but overlooks the risk to susceptible populations. We conducted a nationwide HBV seroepidemiological study to explore the next hepatitis B control strategy.MethodsWe used sera derived from healthy individuals collected nationwide from 2005 through 2011 to investigate the HBsAg seroprevalence among children aged 4–9 years and 10–15 years (3000 samples) and hepatitis B core antibody (HBcAb) seroprevalence among people 10–39 years of age (600 samples).FindingsAmong sera from 3000 children, 5 (0.17%) specimens were HBsAg-positive. There was no significant difference in HBsAg prevalence between age groups. Among 600 samples, 15 (2.5%) were HBcAb-positive. Out of 15 samples, 4 were from teenagers. Both HBsAg- and HBcAb-positive sera were found mainly in the Southern area of Japan.ConclusionThe prevalence of HBsAg among children was 0.17% in the present study. This is higher than the prevalence reported in previous studies performed in the local area or in blood donors. The prevalence of HBcAb is also higher than we estimated. One of the reasons for this discrepancy from previous studies may be due to the small sample size and the impact of HBV high-endemic areas included in the present nationwide study. Nevertheless, our findings revealed that the opportunities for acquiring HBV infection in the susceptible population were more frequent than we thought, especially in some localities. Hepatitis B vaccination should be introduced into the routine child immunization program for susceptible populations, and the selective vaccination program should be continued for high-risk children.     

乙型肝炎疫苗接种预防乙型肝炎和肝癌效果

目的 评价乙型肝炎(乙肝)疫苗预防乙肝和原发性肝细胞癌(肝癌)的保护效果。方法采用出生队列调查、横断面血清流行病学调查以及乙肝发病和肝癌死亡监测,对乙肝疫苗的预防效果进行评价。结果 婴儿乙肝疫苗普种后14年,接种人群HBsAg阳性率为0.7％～2.9％(平均为1.5％),保护率为83.5％～96.6％;HBV感染率为1.1％～5.1％(平均为2.2％),保护率为93.5％～98.4％。乙肝疫苗普种后15年,1～14岁年龄组乙肝发病率为1.4/10万,下降92.4％;0～19岁组肝癌死亡率为0.17/10万,下降19.23倍。结论 婴儿乙肝疫苗普种可降低急性乙肝发病率和肝癌死亡率。     

A mathematical model to estimate global hepatitis B disease burden and vaccination impact

BACKGROUND: Limited data are available regarding global hepatitis B virus (HBV)-related morbidity and mortality and potential reduction in disease burden from hepatitis B vaccination. METHODS: A model was developed to calculate the age-specific risk of acquiring HBV infection, acute hepatitis B (illness and death), and progression to chronic HBV infection. HBV-related deaths among chronically infected persons were determined from HBV-related cirrhosis and hepatocellular carcinoma (HCC) mortality curves, adjusted for background mortality. The effect of hepatitis B vaccination was calculated from vaccine efficacy and vaccination series coverage, with and without administration of the first dose of vaccine within 24 h of birth (i.e. birth dose) to prevent perinatal HBV infection. RESULTS: For the year 2000, the model estimated 620,000 persons died worldwide from HBV-related causes: 580,000 (94%) from chronic infection-related cirrhosis and HCC and 40,000 (6%) from acute hepatitis B. In the surviving birth cohort for the year 2000, the model estimated that without vaccination, 64.8 million would become HBV-infected and 1.4 million would die from HBV-related disease. Infections acquired during the perinatal period, in early childhood (<5 years old), and > or = 5 years of age accounted for 21, 48, and 31% of deaths, respectively. Routine infant hepatitis B vaccination, with 90% coverage and the first dose administered at birth would prevent 84% of global HBV-related deaths. CONCLUSION: Globally, most HBV-related deaths result from the chronic sequelae of infection acquired in the perinatal and early childhood periods. Inclusion of hepatitis B vaccine into national infant immunization programs could prevent >80% of HBV-related deaths.     

陕西省人群乙型肝炎血清流行病学调查

目的了解陕西省人群乙型肝炎（乙肝）病毒（HBV）感染现状,评价接种乙肝疫苗（HepB）15年后人群血清流行病学变动情况。方法采用多阶段随机抽样方法,抽取1～59岁人群2 224人进行问卷调查并采集血标本,用ELISA方法检测HBV血清学标志。结果调查人群HBsAg、抗-HBs、抗-HBc标化阳性率分别为3.50%、48.51%、24.45%,HBV标化感染率为37.58%。HepB接种率为50.09%,接种人群HBsAg阳性率（1.62%）及HBV感染率（8.80%）低于未接种人群（4.05%、50.00%）。15岁以下儿童HBsAg、抗-HBc阳性率和HBV感染率低于15岁以上人群,而抗-HBs阳性率、HepB接种率高于15岁以上人群。HBsAg阳性率、HBV感染率较1992年流行病学调查结果分别下降54.78%、31.86%,抗-HBs阳性率上升60.79%。HBV感染率农村（33.33%）高于城市（24.17%）,HepB接种率城市（88.61%）高于农村（75.96%）。结论陕西省实施HepB接种15年后,HBsAg阳性率、HBV感染率均有不同程度下降,15岁以下儿童下降更为明显。     

中国乙型肝炎疫苗免疫策略及新生儿以外人群接种乙型肝炎疫苗的可行性分析

中国是乙型肝炎(乙肝)病毒(Hepatitis B Virus,HBV)高感染率国家,实施国家乙肝疫苗(Hepatilis B Vac-cine,HepB)预防接种后,乙肝病毒表面抗原(HBsAg)携带率在免疫人群中显著下降,控制乙肝取得显著成就.然而,要进一步降低HBV的感染率,需不断完善国家的免疫策略,在落实新生儿HepB免疫规划的基础上,将HepB预防接种向儿童和成人高危人群扩大.     

深圳市儿童乙型肝炎血清流行病学调查分析

目的探讨深圳市儿童乙型病毒性肝炎(简称乙肝)流行现状及乙肝疫苗应用效果。方法采用多阶段整群系统随机抽样方法抽取调查户,对深圳市1～14岁常住人口进行问卷调查并采血检测HBsAg、抗-HBs及抗-HBc。采用Epidata 3.2软件建立调查数据库,利用SPSS 16.0软件进行数据处理分析,两组之间率比较采用χ2检验,P<0.05为差异有统计学意义。结果调查1～14岁儿童1 653人,HBsAg阳性率2.06%,抗-HBs阳性率74.53%,抗-HBc阳性率5.32%,HBV感染率9.62%。有乙肝疫苗免疫史儿童1 349人,HBsAg阳性率1.85%、抗-HBs阳性率75.02%、抗-HBc阳性率4.60%及HBV感染率5.41%;无乙肝疫苗免疫史儿童92人,HBsAg阳性率4.35%、抗-HBs阳性率68.48%、抗-HBc阳性率10.87%及HBV感染率73.91%;有无乙肝疫苗免疫史儿童HBsAg阳性率、抗-HBs阳性率差异无统计学意义,抗-HBc阳性率、HBV感染率差异有统计学意义,(χ2=7.14、457.83,P均<0.01)。乙肝疫苗免疫3年以内儿童601人,其中HBsAg阳性率为0、抗-HBs阳性率73.71%、抗-HBc阳性率2.0%、HBV感染率2.0%;免疫7～9年183人,其中HBsAg阳性率5.46%、抗-HBs阳性率79.23%、抗-HBc阳性率8.74%、HBV感染率11.48%。乙肝疫苗不同免疫年限儿童抗-HBs阳性率差异无统计学意义,HBsAg阳性率、抗-HBc阳性率、HBV感染率差异有统计学意义(χ2=29.53、36.88、43.75,P均<0.01)。结论持续保持较高的乙肝疫苗接种率,可以有效降低乙肝流行率。研究和推行乙肝疫苗加强免疫策略也是乙肝防治工作重点之一。     

Acute hepatitis B among children and adolescents--United States, 1990-2002

Since the 1991 adoption of a comprehensive strategy to eliminate hepatitis B virus (HBV) transmission in the United States, the incidence of acute hepatitis B cases has declined steadily. Declines have been greatest among children born after the 1991 recommendations for universal infant hepatitis B vaccination were implemented. In 1995, the elimination strategy was expanded to include routine vaccination of all adolescents aged 11-12 years and, in 1999, to include children aged < or =18 years who had not been vaccinated previously. To describe the epidemiology of acute hepatitis B in children and adolescents in the United States, CDC analyzed notifiable disease surveillance data collected during 1990-2002 and data collected during 2001-2002 through enhanced surveillance of reported cases of acute hepatitis B in children born after 1990. This report summarizes the results of that analysis, which indicated that the rate of acute hepatitis B in children and adolescents decreased 89% during 1990-2002 and that racial disparities in hepatitis B incidence have narrowed. Many confirmed cases in persons born after 1990 occurred among international adoptees and other children born outside the United States. Continued implementation of the hepatitis B elimination strategy and accurate surveillance data to monitor the impact of vaccination are necessary to sustain the decline of acute hepatitis B among children.     

Trend in incidence of hepatitis B virus infection during a decade of universal childhood hepatitis B vaccination in Saudi Arabia

Since 1990, the national strategy to eliminate hepatitis B virus (HBV) infection in Saudi Arabia has included universal administration of HBV vaccine to all infants. From 1990 to 1995 this vaccine was also routinely administered to children at school entry. The prevalence of hepatitis B surface antigen (HBsAg) among children before this programme was reported to be 6.7%. The objective of this study was to describe the trend in incidence of HBV infection over a decade of surveillance following the introduction of this programme. From January 1990 to December 1999 a total of 30,784 cases of HBV infection (positive for HBsAg) were reported. The total number of HBV infections among children <15 years of age was 4180 cases, with a prevalence of 0.05%. The total number of HBV infections among adults was 26,604 cases, with a prevalence of 0.22%. The prevalence varied by region, ranging from 0.03% to 0.72% with a mean prevalence of 0.15%. There was a clear decline in incidence among children whereas the incidence in adults slightly rose, perhaps owing to population growth estimated to be 3.3% annually. This study showed that the universal childhood HBV vaccination programme had an enormous positive impact on HBsAg seroprevalence among children in Saudi Arabia.     

Reduction in the hepatitis B related burden of disease--measuring the success of universal immunisation programs.

There is collective evidence from countries of both low and high endemicity that administration of hepatitis B vaccination at birth saves lives and reduces the burden of disease from acute and chronic infection. However, a discussion on the cost-effectiveness of vaccination for HBV is beyond the scope of this article. In Australia, longer term follow-up of HBV disease burden is required following the more recent introduction of routine and universal infant vaccination. Universal vaccination for HBV at birth can be seen as a 'safety-net' against infection at a very young age. However, it is estimated that the effect of universal infant vaccination will not be evident for at least another 15 years in Australia. The obstacles to vaccination with HBV, which have historically included fears that the vaccine may be linked to multiple sclerosis, should be put to rest, and concerns about the thiomersal content allayed by communicating the current availability of thiomersal-free vaccines to all providers and parents or care-givers. Furthermore, ongoing adverse events surveillance should be in place to detect any rare adverse events which may be related to the vaccine. Currently, more than one half of the world's infants are still not being immunised for HBV, and the need for a global initiative for universal infant hepatitis B vaccination is apparent. This is especially true for countries with high prevalence, and the costing issues and logistics of such an initiative still remain to be addressed. In addition, there is a need to address the implementation of guidelines for screening and vaccination of families who have immigrated to Australia from countries with a high prevalence of hepatitis B.     

Prevalence of chronic hepatitis B virus infection before and after implementation of a hepatitis B vaccination program among children in Nepal

Background

In Nepal, an estimated 2–4% of the population has chronic hepatitis B virus (HBV) infection. To combat this problem, from 2002 to 2004, a national three dose hepatitis B vaccination program was implemented to decrease infection rates among children. The program does not currently include a birth dose to prevent perinatal HBV transmission. In 2012, to assess the impact of the program, we conducted a serosurvey among children born before and after vaccine introduction.

Methods

In 2012, a cross-sectional nationally representative stratified cluster survey was conducted to estimate hepatitis B surface antigen (HBsAg) prevalence among children born from 2006 to 2007 (post-vaccine cohort) and among children born from 2000 to 2002 (pre-vaccine cohort). Demographic data, as well as written and oral vaccination history were collected. All children were tested for HBsAg; mothers of HBsAg positive children were also tested. Furthermore, we evaluated the field sensitivity and specificity of the SD Bioline HBsAg rapid diagnostic test by comparing results with an enzyme immunoassay.

Results

Among 2181 post-vaccination cohort children with vaccination data by either card or recall, 86% (95% confidence interval [CI] 77–95%) received ≥3 hepatitis B vaccine doses. Of 1200 children born in the pre-vaccination cohort, 0.28% (95% CI 0.09–0.85%) were positive for HBsAg; of 2187 children born in the post-vaccination cohort, 0.13% (95% CI 0.04–0.39%) were positive for HBsAg (p = 0.39). Of the six children who tested positive for HBsAg, two had mothers who were positive for HBsAg. Finally, we found the SD Bioline HBsAg rapid diagnostic test to have a sensitivity of 100% and a specificity of 100%.

Conclusions

This is the first nationally representative hepatitis B serosurvey conducted in Nepal. Overall, a low burden of chronic HBV infection was found in children born in both the pre and post-vaccination cohorts. Current vaccination strategies should be continued.     

Assessing the impact of the routine childhood hepatitis B immunization program and the need for hepatitis B vaccine birth dose in Sierra Leone, 2018

Sierra Leone is highly endemic for hepatitis B virus (HBV) infection and thus recommends three doses of hepatitis B vaccine (HepB3) from 6 weeks of age but does not recommend a birth dose (HepB-BD) to prevent mother-to-child transmission (MTCT). We evaluated impact of the existing HepB3 schedule and risk for MTCT of HBV. We conducted a community-based serosurvey among 4–30-month-olds, their mothers, and 5–9-year-olds in three districts in Sierra Leone. Participants had an HBV surface antigen (HBsAg) rapid test; all HBsAg-positive and one HBsAg-negative mother per cluster were tested for HBV markers. We collected children’s HepB3 vaccination history. Among 1889 children aged 4–30 months, HepB3 coverage was 85% and 20 (1·3% [95% CI 0·8–2·0]) were HBsAg-positive, of whom 70% had received HepB3. Among 2025 children aged 5–9 years, HepB3 coverage was 77% and 32 (1·6% [1·1–2·3]) were HBsAg-positive, of whom 56% had received HepB3. Of 1776 mothers, 169 (9·8% [8·1–11·7]) were HBsAg-positive. HBsAg prevalence was 5·9% among children of HBsAg-positive mothers compared to 0·7% among children of HBsAg-negative mothers (adjusted OR = 10·6 [2·8–40·8]). HBsAg positivity in children was associated with maternal HBsAg (p = 0·026), HBV e antigen (p < 0·001), and HBV DNA levels ≥ 200 000 IU/mL (p < 0·001). HBsAg prevalence was lower among children than mothers, for whom HepB was not available, suggesting routine infant HepB vaccination has lowered HBV burden. Since HBsAg positivity in children was strongly associated with maternal HBV infection and most of the HBsAg-positive children in the survey received HepB3, HepB-BD may prevent MTCT and chronic HBV infection.     

The effect of introduction of universal childhood hepatitis B immunization in South Africa on the prevalence of serologically negative hepatitis B virus infection and the selection of immune escape variants.

The effect of universal hepatitis B vaccination on the prevalence of serologically negative hepatitis B virus infection (HBV) and the emergence of HBsAg variants is unknown. We prospectively studied two different cohorts of 12--24 month old children in South Africa. They consisted of the unvaccinated children (n=459) born before the introduction of universal vaccination and the vaccinated children (n=1213) between 1 and 2 years after the introduction of the vaccination program. The frequency of detecting HBV DNA by PCR was reduced from 6.5% in unvaccinated children to 0.3% in vaccinated children (P<0.00001). There were no unique amino acid substitutions within the major hydrophilic region of the S sequence in both pre- and post-vaccination samples. Universal childhood vaccination reduced the frequency of serologically negative HBV infection and did not necessarily lead to selection of escape variants.     

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.     

母亲乙型肝炎病毒携带状况与新生儿乙肝疫苗免疫效果关系的探讨

目的分析母亲乙肝病毒（hepatitis B virus,HBV）携带状况与新生儿乙肝疫苗（hepatitis B vaccine,HepB）免疫效果之间的关系,为阻断HBV母婴传播提供依据。方法在邯郸市随机抽取8022名满7月龄--2周岁儿童及其母亲,调查儿童的HepB接种情况,采取试纸和酶联免疫吸附试验方法检测母子HBV标志物携带状况,并检测HBsAg阳性母亲的HBV基因型。结果母亲HBsAg阳性率为2．43％,儿童阳性率为0．45％,HepB保护率为81．48％。143名HBsAg阳性母亲中有127名C型,占97．69％。26对母子名HBsAg均阳性的母亲中,大三阳9名,小三阳5名,HBsAg和HBcAb阳性10名,三者差异有统计学意义（χ^2=6．03,P〈0．05）。结论母亲HBV基因型中以C型为主。阻断HBsAg阳性的母婴传播应采取联合接种HepB和乙肝高效免疫球蛋白等综合措施,同时,HBsAg和HBcAb双阳性母亲在母婴传播中的意义不可忽视。     

Hepatitis B vaccination coverage among adults--United States, 2004

Hepatitis B virus (HBV) infection is a major cause of cirrhosis and liver cancer in the United States. The Advisory Committee on Immunization Practices (ACIP) has recommended a comprehensive strategy to eliminate HBV transmission, including prevention of perinatal HBV transmission; universal vaccination of infants; catch-up vaccination of unvaccinated children and adolescents; and vaccination of unvaccinated adults at increased risk for infection. The incidence of acute hepatitis B has declined 75%, from 8.5 per 100,000 population in 1990 to 2.1 per 100,000 population in 2004, with the greatest declines (94%) among children and adolescents. Incidence remains highest among adults, who accounted for approximately 95% of the estimated 60,000 new infections in 2004. To measure hepatitis B vaccination coverage among adults, data were analyzed from the 2004 National Health Interview Survey (NHIS). This report summarizes the results of that analysis, which indicated that, during 2004, 34.6% of adults aged 18-49 years reported receiving hepatitis B vaccine, including 45.4% of adults at high risk for HBV infection. To accelerate elimination of HBV transmission in the United States, public health programs and clinical care providers should implement strategies to ensure that adults at high risk are offered hepatitis B vaccine.     

Hepatitis B vaccination coverage among Asian and Pacific Islander children--United States, 1998

Asian and Pacific Islander (API) children in the United States have high rates of hepatitis B virus (HBV) infection (1-3). To prevent these infections, hepatitis B vaccination has been recommended for these children since the vaccine was first licensed by the Food and Drug Administration in 1981 (4). Recommendations have included universal hepatitis B vaccination of API infants beginning in 1990 and catch-up vaccination for API children aged <7 years (5). These recommendations were reinforced in 1991 when hepatitis B vaccination was recommended for all infants, particularly in populations such as API children with high rates of early childhood HBV infection (6). In 1995, vaccination was recommended for unvaccinated API children aged <11 years and catch-up vaccination for children aged 11-12 years who had not received hepatitis B vaccine (HepB) (7). Series completion among API children aged 19-35 months increased from 39% in 1994 to 88% in 1997 (8). However, among older API children, hepatitis B vaccination coverage was 10% in 1995 (7). In 1998, to examine trends in hepatitis B vaccination catch-up coverage among API children born before 1994, surveys were conducted in six U.S. cities. This report summarizes the results of the surveys, which indicate varying coverage among API children and suggest a need for continued focused vaccination programs for this population.     

浙江省1990-2006年疫苗时代乙型病毒性肝炎流行病学特征分析

目的：分析乙型病毒性肝炎（乙肝）疫苗纳入计划免疫管理前后浙江省乙肝流行病学特征的变化,为调整防控措施提供依据。方法：收集疫情、流行病学调查相关资料,运用描述流行病学方法整理资料,使用SPSS13．0进行统计处理。结果：乙肝发病率自1990年缓慢波动上升,2006年全人群乙肝发病率较1990年上升65．83％,HBV感染率较1992年下降12．99％,其中儿童乙肝发病率、HBV感染率较免疫管理前平均分别下降了66．84％、89．44％,年龄发病高峰在管理前是5～9岁和20～34岁组,在管理后仅是20～34岁组,且高峰上升明显,HBV感染率随年龄增加而升高。乙肝发病无明显季节高峰。高发地区由舟山、杭州向温州、金华、丽水转移。各年龄组人群乙肝疫苗接种率与发病率和感染率的变化呈负相关（P〈O．001）。结论：乙肝疫苗纳入计划免疫管理后,儿童乙肝发病率及HBV感染率大幅下降。扩大乙肝疫苗接种人群,尤其是育龄期青壮年,能加快控制乙肝。     

A window of opportunity: declining rates of hepatitis B virus infection among injection drug users in Rio de Janeiro, and prospects for targeted hepatitis B vaccination.

OBJECTIVES: To measure hepatitis B virus (HBV) infection rates among injection drug users in Rio de Janeiro, Brazil, and to report their knowledge of and attitudes toward hepatitis and HBV vaccination. METHODS: 609 injection drug users recruited in Rio de Janeiro between 1999 and 2001 answered a questionnaire and were tested for hepatitis B and other blood-borne infections. Questions covered sociodemographic information, alcohol and illicit drug consumption, drug injection and sexual practices, medical history, and knowledge about HIV, AIDS and viral hepatitis. RESULTS: The prevalence of HBV infection was 27.1%, with 3.4% of the sample positive for HbsAg (active infection) and 0.8% positive for anti-HBs (indicating previous HBV vaccination). Most interviewees (81.3%) were aware of at least one form of viral hepatitis and received information from many different sources. In agreement with laboratory findings, 96.7% of the interviewees stated they had never been vaccinated against hepatitis B, but almost all unvaccinated interviewees (97.8%) said they would volunteer to be vaccinated if HBV vaccination were available. CONCLUSIONS: Few of the injection drug users surveyed had ever been vaccinated against HBV. Although most were aware of the risks posed by viral hepatitis, this awareness seldom translated into consistent behavioral change. The participants' willingness to be vaccinated against HBV suggests that the implementation of vaccination for this population may help decrease rates of hepatitis B infection.