Rationale for the infant and adolescent vaccination programmes in Italy

In Italy in the 1980s, the incidence of acute hepatitis B was about 13 per 100,000, corresponding on average to 7500 new symptomatic cases per year was about 3%, making Italy an area of intermediate endemicity. HBV infection was also associated with 12 per 100,000 deaths from cirrhosis and with 5.1 per 100,000 deaths from hepatocellular carcinoma. In view of the large numbers of pregnant women who were hepatitis B surface antigen (HBsAg)-positive, selective hepatitis B vaccination of all newborns to these mothers and of other high-risk groups was introduced in 1983. Compliance was high among the newborns but low in other high-risk groups. Hepatitis vaccination was adopted in Italy in 1991, including each year all newborns, all adolescents aged 12 years and other high-risk groups. Compliance has been nearly 95% for newborns and 80% for adolescents. Since the introduction of vaccination, both the incidence of acute hepatitis B and the prevalence of HBV carriage have fallen, the latter from 3.4% in 1985 to 0.9% in 1996. There is good evidence that these decreases are mainly the result of the vaccination programmes. Although the full economic impact cannot yet be assessed, about 18,000 cases of acute HBV infection have been prevented over the 6 years since starting the mass vaccination programme, with cost savings of about US$ 244,308,000.     

The hepatitis B immunization programme in Singapore

A voluntary immunization programme to prevent perinatal transmission of hepatitis B virus (HBV) infection in Singapore was implemented on 1 October 1985 as an integral component of the national childhood immunization programme. Up to April 1988, a total of 68,845 mothers who attended government maternal and child health clinics were screened for the disease. Of these, 2432 (3.5%) were positive for hepatitis B surface antigen (HBsAg) and 904 (1.3%) for hepatitis B e antigen (HBeAg). Virtually all the babies born to carrier mothers completed the full immunization schedule; and in addition, those of HBeAg-positive mothers were given a dose of hepatitis B immunoglobulin at birth. The hepatitis B immunization programme was extended on 1 September 1987 to cover all newborns. About 90% of the 15,943 babies delivered in government institutions from September 1987 to April 1988 were immunized at birth, with the subsequent doses being administered at maternal and child health clinics at 4-6 weeks and 5 months later. More than 85% of the children given the full course of plasma-derived and yeast-derived hepatitis B vaccine from birth continued to have protective antibody to HBV two years after immunization. The programme is being closely monitored to assess the duration of immunity and the need for booster doses, while seronegative adults are also being encouraged to be vaccinated.     

Prevention of perinatal hepatitis B transmission in Haimen City,China: Results of a community public health initiative

In regions where hepatitis B virus (HBV) is endemic, perinatal transmission is common. Infected newborns have a 90% chance of developing chronic HBV infection, and 1 in 4 will die prematurely from HBV-related liver disease. In 2010, the Hepatitis B Foundation and the Haimen City CDC launched the Gateway to Care campaign in Haimen City, China to improve awareness, prevention, and control of HBV infection citywide. The campaign included efforts to prevent perinatal HBV transmission by screening all pregnant women for hepatitis B surface antigen (HBsAg), following those who tested positive, and administering immunoprophylaxis to their newborns at birth. Of 5407 pregnant women screened, 185 were confirmed HBsAg-positive and followed until delivery. At age one, 175 babies were available for follow up testing. Of those, 137 tested negative for HBsAg and positive for antibodies to HBsAg, indicating protection. An additional 34 HBsAg-negative babies also tested negative for antibodies to HBsAg or had indeterminate test results, were considered to have had inadequate immune responses to the vaccine, and were given a booster dose. A higher prevalence of nonresponse to HBV vaccine was observed among babies born to hepatitis B e antigen (HBeAg)-positive mothers and mothers with high HBV DNA titers. The remaining 4 babies tested positive for HBsAg and negative for antibodies, indicative of active HBV infection. The mothers of all 4 had viral loads ≥8 × 10⁶ copies/ml in the third trimester. Although inadequate response or nonresponse to HBV vaccine was more common among babies born to HBeAg-positive and/or high viral load mothers, these risk factors did not completely predict nonresponsiveness. All babies born to HBV-infected mothers should be tested upon completion of the vaccine series to ascertain adequate protection. Some babies of HBeAg-positive mothers with high viral load may still become HBV infected despite timely immunoprophylaxis with HBV vaccine and HBIG.     

A nationwide vaccination programme in Italy against hepatitis B virus infection in infants of hepatitis B surface antigen-carrier mothers

In order to prevent hepatitis B virus (HBV) infection of infants of hepatitis B surface antigen (HBsAg)-positive mothers, a nation-wide immunization programme was initiated in Italy in January 1984. During the first 3 years (1984-86), 651,667 out of 1726,000 pregnant women (37.8%) were screened for HBsAg; the percentage of mothers screened increased from 32% in 1984 to 51% in 1986 in 15 of the 21 Italian regions, where data by year were available. HBsAg was present in 15,640 mothers (2.4% of those screened); range by region 0.3-6.4%. All newborns of HBsAg-positive women, regardless of the mother's status of hepatitis Be antigen (HBeAg), were given a single dose (0.5 ml Kg-1) of a hepatitis B immune globulin within 24 h after birth and the first dose of plasma-derived hepatitis B vaccine within 7 days after birth. The immunization coverage rate was 80% in the 3-year period. Protective antibodies were found in greater than 97% of a sample of 1071 infants, immunized from different regions. No serious reactions were observed. On the basis of this field experience, it may be concluded that a nation-wide hepatitis B vaccination programme for infants of HBsAg-carrier mothers would be highly immunogenic and safe. Its implementation, however, requires continuous public education and cooperation from physicians.     

乙型肝炎疫苗长期免疫效果的研究

目的：观察乙肝疫苗普种预防儿童期乙型肝炎病毒（HBV）感染、降低乙肝发病率的免疫效果。方法：建立肝病报告制度，对乙肝发病情况进行监测；以出生队列定群随访和横断面调查方法，观察新生儿接种乙肝疫苗后13年的免疫持久性、HBV感染标志变动和乙肝发病率；用放射免疫法测定HBV感染标志。结果：乙肝疫苗纳入计划免疫轨道，母亲不筛检，新生儿接种常规剂量乙肝疫苗，乙肝疫苗平均接种率达到85％以上。免疫后13年的长期连续定群观察结果和免疫10年后的横断面调查结果显示，免疫人群的HBsAg阳性率已从既往的16.0％下降为2.3％，HBV感染率从既往的51.5％降至3.5％，疫苗预防HBsAg的保护有效率达到89.7％，预防HBV感染的保护率达到96.2％，1-13岁年龄组人群的急性乙型肝炎发病率已由18.38/10万降至1.6/10万，下降了91.3％，保护效果稳定。结论：在肝癌高发区隆安县开展新生儿乙肝疫苗普种，可获得有效控制HBV感染和HBsAg慢性携带的长期免疫效果。     

Hepatitis B in Poland in 1999

A total of 3,508 of hepatitis B cases (including 152 cases of mixed HBV and HCV infections) were reported in Poland in 1999. For the first time since 1979, when registration has began, the incidence decreased below 10.0 and was 9.1 per 100,000. The program of eradication of hepatitis B in Poland has been introduced in 1993 and since then the fourfold decrease in number of hepatitis B cases has been noticed. During the past 7 years there has been a steady decline in hepatitis B incidence. In 1997 the incidence decreased 23% as compared to 1996, followed by 16.8% decrease in 1998 and 13.9% in 1999; the marked differences in incidence in particular voivodeships have been observed. The overall rate of hospitalized hepatitis B cases in Poland reached 98.1%. A total of 25 cases of hepatitis B (rate 1.2 per 100,000) occurred among children under 4 years of age, who should be vaccinated. Among children aged 5-9 years, of which many could not be vaccinated, the incidence rate was 6 times higher, ranging from 4.9 per 100,000 in girls to 9.8 per 100,000 in boys. The increase of incidence from 5.3 to 9.2 was observed in young people (14-24 years old). Data from the study of serological markers of hepatitis B, conducted among 4,500 health care workers during 1998-2000, have indicated that about 22% of health care workers have been infected with HBV (in 21% of persons anti-HBc and in 1% anti-HBc together with HBsAg were detected).     

The first five years of universal hepatitis B vaccination in South Africa: evidence for elimination of HBsAg carriage in under 5-year-olds.

South Africa implemented a vaccine against hepatitis B virus (HBV) into the Expanded Programme on Immunisation (EPI) in April 1995. The HBV vaccine is given at 6, 10, and 14 weeks, in parallel with OPV, DTP and Hib vaccines. This study assessed the impact of universal childhood HBV vaccination programme in reducing HBsAg carriage, in the first five years (1995--1999) since its implementation. In parallel, we investigated the current burden of HBV infection in mothers of vaccinees and the adult general population. A total of 598 babies (mean age=23.3 months) who received 3 doses of 1.5 microg/0.5 ml Hepaccine-B (Cheil) were recruited from the Northern Province (one of the nine provinces in South Africa). HBsAg, anti-HBs, anti-HBc, HBeAg and anti-HBe were tested using the IMx or Axsym kits (Abbott Laboratories). PCR assays were performed following established protocols. The overall seroprotection rate (i.e. anti-HBs titre> or =10 mIU/ml) was 86.8% (519/598) in vaccinated babies, while 13.2% had anti-HBs levels<10 mIU/ml. Seroprotection rates and geometric mean titres (GMT) decreased significantly with increasing age, possibly reflecting waning anti-HBs titre over time. Total HBV exposure (positive for either HBsAg, anti-HBs, or anti-HBc) was 31.0% (58/187) in mothers of vaccinees and 40% (72/180) in the adult general population. HBsAg carrier rate was virtually similar in both groups (3.2% in mothers of vaccinees vs. 3.3% in the general population). Against this background, no vaccine failures resulting in HBsAg and HBV DNA positivity were seen in vaccinated babies, including 6 babies born to HBsAg positive carrier mothers (one carrier mother was positive for HBeAg and HBV DNA). However, 0.9% (5/582) babies, aged between 8--11 months, tested positive for anti-HBc, all of whom had anti-HBs titres>10 mIU/ml and were negative for HBV DNA. Anti-HBc positivity was probably maternal in origin, or may represent sub-clinical averted HBV infections. It can be concluded that the HBV vaccine is highly effective within the framework of the South African EPI and already shows a positive impact in the elimination of HBsAg carrier rate in children<5 years.     

HBsAg阴性母亲新生儿乙型肝炎疫苗免疫后HBV感染状况的长期随访

为了解HBsAg阴性母亲的新生儿乙型肝炎（乙肝）疫苗免疫后,乙肝病毒再感染的状况和转归,为乙肝免疫策略提供依据．选择湘潭市和正定县现场829例HBsAg阴性母亲的新生儿作为观察对象,进行了平均10～11年的随访．结果首次检查有6例HBsAg阳性,7例抗-HBc阳性,均发生在农村现场,在那里首针免疫时间为101天．据此推测,上述感染很可能是发生在免疫之前．在随访中共发现17例执-HBc阳转,其中6例变为持续阳性。抗-HBc阳转者的持续阳性率为0.72％（6／829）．随访中未发现任何HBsAg阳转者．这表明,HBsAg阴性母亲的新生儿,在乙肝疫苗免疫后HBV再感染的机率很低（0.72％）,而且多为一过性（11／17）．对此种再感染的性质做了讨论．     

新生儿乙型肝炎病毒感染情况的研究

目的 了解广州市新生儿围产期ＨＢＶ的感染情况。方法 采用酶联免疫吸附试验（ＥＬＩＳＡ）和斑点发校技术对２４１例新生儿脐血的乙肝病毒标志物进行检测。结果 广州市新生儿围生期ＨＢｓＡｇ阳性率为２．０７％（５／２４１）,ＨＢｓＡｇ阴性、单纯Ａｎｔｉ－ＨＢ阳性且ＨＢＶ ＤＮＡ阳性者１９例,占７．８９％（１９／２４１）,新生儿脐血ＨＢＶ感染率为９．９６％（２４／２４１）,现症ＨＢＶ感染母亲的新生儿脐血ＨＢＶ     

Post-vaccination serologic testing of infants born to hepatitis B surface antigen positive mothers in 4 provinces of China

ObjectiveTo evaluate prenatal maternal hepatitis B virus (HBV) screening and post-vaccination hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBs) status and titers of babies born to HBsAg positive mothers, and to provide evidence for development of standard postvaccination serologic testing (PVST) strategies for babies born to HBsAg positive mothers in China.MethodsIn 2014, we conducted a baseline survey of HBV mother to child transmission (MTCT) interruption strategy implementation and PVST for babies born to HBsAg positive mothers after received 3 doses of hepatitis B vaccine (HepB) in 8 counties in 4 Provinces. Bivariate analysis and multivariable analyses modeled statistically significant predictor variables associated with infant HBsAg, anti-HBs positive, anti-HBs titer.ResultsAmong the 1563 infants born to HBsAg positive mothers, 1025 (65.6%) maternal-infant pairs were enrolled in PVST after receiving 3 doses of HepB. 38 infants tested HBsAg positive for an HBsAg positive rate of 3.7%. Maternal hepatitis B e antigen (HBeAg) status and age of infant were significantly associated with infant HBsAg positivity. A total of 932 infants were anti-HBs positive when tested at 7–24 months of age, yielding an anti-HBs positivity rate of 90.9%. Maternal HBeAg status was the factor associated with infant anti-HBs status. Amount of antigen of HepB and infant’s age were most associated with anti-HBs titers. PVST performed 1–2 months after the 3rd dose of HepB was associated with the highest anti-HBs level and the anti-HBs Geometric Mean Concentration (GMC) decreased as the PVST intervals prolonged.ConclusionsIn China, perinatal HBV transmission is approaching the theoretical minimum possible with the current strategy of HepB coupled with HBIG administration for HBV-exposed newborns. PVST of infants born to an HBsAg positive mother is an essential strategy to ensure full protection for vaccine non-responders and appropriate medical care for those infected.     

乙型肝炎母婴传播的研究

本文系对80名HBsAg阳性孕妇的婴儿进行HBV感染的调查和随访资料。80份脐血HBsAg均阴性。有36名婴儿于生后40~205天（平均115.9天）呈HBsAg阳性（45%）。母血HBsAg阳性者对婴儿的传播率最高（75%），HBsAg阴性者传播率较低（23.08%）。抗HBe阳性者未见HBsAg阳转。资料提示传播途径以分娩时感染为主，但作者曾见1名胎儿于足月临产前死亡，病理检查显示肝组织有急性病毒性肝炎变化，故宫内感染的可能性尚难排除。母婴传播的预防，除须防止分娩过程中的胎盘创伤及母血污染新生儿破损的皮肤粘膜外，尤应强调对HBsAg和HBeAg双阳性母亲新生儿进行特异预防。婴儿吞咽羊水、乳汁和唾液是否可引起婴儿感染，尚需细致观察，积累更多的资料来说明。     

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。     

重组(酵母)乙型肝炎疫苗免疫后5年随访结果

目的 探讨新生儿接种国产重组(酵母)乙型肝炎(乙肝)疫苗后的免疫效果,并与血源乙肝疫苗效果比较.方法 对1997年出生并接种重组(酵母)乙肝疫苗的新生儿隔年随访一次,采血检测乙肝病毒表面抗原(HBsAg),乙肝病毒表面抗体(抗-HBs)和乙肝病毒核心抗体(抗-HBc),1998年以后对乙肝免疫人群开展急性乙肝发病监测....     

Hepatitis B immunity in adolescents and necessity for boost vaccination: 23 years after nationwide hepatitis B virus vaccination program in Taiwan

The first universal hepatitis B vaccination program for newborns in the world was launched in Taiwan in July 1984. Most studies on the effectiveness of hepatitis B vaccination focused on the seroprevalence of HBs Ag among children under 14 years old. Only few studies focused on the seropositivity of anti-HBs among adolescents aged 15–18 years old. The present study aimed to evaluate the impact of the nationwide hepatitis B vaccination program on the immunity to HBV infection and the necessity of boost among adolescents. In this study including eight annual seroprevalence surveys from 2000 to 2007, 2342 college entrants (1589 15-year-olds in group I and 753 18-year-olds in group II) and 1851 university freshmen (18-year-olds in group III) participated. Subjects identified anti-HBs, HBs Ag and anti-HBc negative were given boost three doses of HBV vaccine. The HBs Ag seroprevalence was 11.6%, 3.5% and 1.0% for participants who were born before 1984, 1984–1986 and after 1986. The anti-HBs-seropositive rates were significantly higher in group II (83.1%) than in group I (53.0%) and group III (53.5%). All 572 participants who were seronegative for anti-HBs, HBs Ag and anti-HBc became anti-HBs-seropositive after catch-up vaccination. It is concluded that the anti-HBs-seropositive rate decreased to 50% in 15 years after vaccination, and boost vaccination was 100% effective. The necessity and age for boost among anti-HBs negative adolescents and the timing of the first immunization should be further evaluated.     

江苏省农村地区儿童乙型肝炎疫苗免疫效果及其影响因素研究

目的探讨江苏省农村地区儿童接种乙型肝炎(乙肝)疫苗后免疫效果及其影响因素。方法采用多阶段分层随机整群抽样方法,抽取江苏省农村地区在实施乙肝疫苗计划免疫后出生的农村儿童为研究对象,检测HBsAg、抗-HBs标志,对抗-HBs阴转儿童进行不同种类疫苗的加强免疫,并分析HBsAg阳性儿童乙肝病毒(HBV)感染的危险因素。结果2522名1～7岁儿童中HBsAg阳性率在0．28%～1．28%之间,抗-HBs随年龄增加而逐渐下降,由1岁时的76．7%降至7岁时的45．5%;出生时未及时接种乙肝疫苗的儿童的HBV感染率显著高于及时接种儿童(1．4%:0．5%, P=0．031);应用不同剂量疫苗加强免疫后,抗-HBs阳转率均为90%以上。结论江苏省农村地区计划免疫适龄儿童人群的HBsAg阳性率为0．28%～1．28%,平均为0．8%,儿童中HBV感染主要为母婴传播,并与未及时接种乙肝疫苗有关。     

Universal screening for hepatitis B among pregnant women led to 96% vaccination coverage among newborns of HBsAg positive mothers in Denmark

In Denmark selective screening programs of pregnant women for hepatitis B missed 30-50% of high-risk groups and in late 2005 a universal screening of pregnant women for HBsAg was implemented.During a 2-year period a prospective enhanced surveillance of the universal screening was performed to examine the effectiveness of universal HBV-screening of pregnant women and HBV-immunizations of their newborn, and to provide a prevalence-estimate for HBV in Denmark. On a opt out basis all women in Denmark attending antenatal care were tested for hepatitis B serology. Vaccination data of the newborns and households of HBsAg positive pregnant women were assembled.Among 140,376 HBsAg tests of pregnant women, 371 (0.26%) were positive. The prevalence among women of Danish origin was 0.012% and 2.74% among foreign born women, highest for women from Southeast Asia (14.5%). Genotype C was the most prevalent (37%) and 13% had a HBVDNA ≥10⁸ IU/ml. The prevalence estimate of chronic hepatitis B in Denmark was 0.2-0.3% in the general population.Among children born within the project period, 96% received vaccination at birth compared to 50% of siblings born prior to universal screening. During 3 years of passive follow-up two transmissions (0.5%) have been notified. Among children born of the positive mothers prior to the trial-period 7.3% had been notified.Thus the prevalence of HBV positive mothers has more than doubled in Denmark over the last 40 years, but among women of Danish origin it has decreased 10-fold. By replacing selective screening with universal, identification of newborns in need of HBV-immunization was increased from 50% to almost complete coverage, and also identifies mothers with high viral load for evaluation of pre-term treatment to interrupt in utero transmission.     

The long-term efficacy of Chinese hamster ovary cell derived hepatitis B vaccine after being used for 14–16 years in Chinese rural communities

ObjectiveTo evaluate the long-term efficacy of Chinese hamster ovary (CHO) cell derived hepatitis B vaccine after being used for 14–16 years in country community in Hebei province in China.MethodA cross-sectional investigation was carried out in 3 of 7 randomly selected rural communities in Zhengding County in 2013. The children who were born between 1997 and 1999 and were vaccinated with three doses of CHO-derived hepatitis B vaccine were eligible to participate in the study. Their sera samples were tested for HBV serological markers. For HBsAg positive children, their historical results were compared, in order to see whether these were new infections.ResultsAmong the 920 participating children, the prevalence of HBsAg, anti-HBs and anti-HBc were 0.65%, 73.15% and 1.20% respectively. The differences between birth-year groups were not significant. When compared with baseline, the vaccine efficacy was 94.2% and the anti-HBs titers of 668 children with sole anti-HBs positivity were 178.8 mIU/ml. By comparing with historical data, no new infection was found in this latest survey. Among 6 mothers of HBsAg positive children, 4 were HBsAg positive, 1 was negative and 1 was unknown.ConclusionThe long-term efficacy of the CHO derived hepatitis vaccine is good and stable for 14–16 years after vaccination. A booster dose seems not necessary. Implementing mother–newborn blocking measures for newborns from HBsAg carrier mothers is urgently needed in the future.     

中国2014年HBsAg阳性母亲所生1～14岁儿童乙型肝炎血清流行病学特征分析

目的 分析HBsAg阳性母亲所生1～14岁儿童乙肝血清流行病学特征。方法 以2014年全国乙型肝炎（乙肝）血清流行病学调查中母亲HBsAg阳性的1～14岁儿童作为研究对象,采用SPSS 18.0软件分析不同性别、年龄、民族、出生地点、城乡、地区的儿童HBsAg、抗-HBs、抗-HBc阳性率以及HBsAg、抗-HBs影响因素等。结果 共分析HBsAg阳性母亲所生的1～14岁儿童645人,HBsAg、抗-HBs、抗-HBc阳性率分别为3.41%（22/645）、71.94%（464/645）、7.60%（49/645）。其中,1～、3～、5～、10～14岁组HBsAg阳性率分别为1.27%（3/236）、3.23%（6/186）、5.71%（8/140）、6.02%（5/83）,抗-HBs阳性率分别为85.17%（201/236）、69.35%（129/186）、56.43%（79/140）、66.27%（55/83）,抗-HBc阳性率分别为4.66%（11/236）、5.38%（10/186）、11.43%（16/140）、14.46%（12/83）。多因素logistic分析结果显示,出生地点、首针乙型肝炎疫苗（HepB）接种时间是影响HBsAg阳性母亲所生儿童HBsAg阳性率的主要因素,在医院外出生儿童HBsAg阳性率高于在医院内出生者（OR=7.47,95%CI：1.50～37.25）,首针HepB出生后> 24 h接种儿童HBsAg阳性率高于出生后≤24 h接种者（OR=6.21,95%CI：2.15～17.99）。结论 我国乙肝母婴阻断取得一定成效。住院分娩和首针HepB及时接种仍是新生儿乙型肝炎母婴阻断工作的重点。     

Hepatitis B virus genotypes: a South Pacific perspective

87-91% but still, 0.6% of those that did respond to vaccination became infected. The infection rate of the vaccinated populations in the Pacific Islands ranged between 0.7 and 3.8%, which is comparable to Taiwan. A vigorous polyclonal response This communication discusses the current status of research in the hepatitis B virus in relation to the South Pacific. The hepatitis B virus (HBV) is a small DNA virus--3200 nucleotides. It has a circular genome and replicates through an RNA intermediate giving this DNA virus many characteristics similar to RNA viruses. Viral genomes can be single-stranded (+ or - sense) or double-stranded. If not vaccinated, infants born to HBeAg positive mothers (i.e. with high viral titer) have a 90% chance of being infected and becoming HBV carriers themselves. Mutants that affect the major antigenic determinant in HBV surface antigens are probably responsible for HBV infection despite immunization and mutants in the polymerase protein may render HBV resistant to therapy with nucleoside analogs. Within HBV seven genotypes A-G have been reported that is, HBV genotype A (HBVA), HBV genotype B (HBVB) etc. HBV is endemic worldwide with an estimated that 5% of the worlds population being carriers. Before the introduction of vaccination programs carrier rates varied between 5-30% in communities of these ethnic groups, and in some cases 80-90% of a community tested positive for HBV markers (i.e. were infected or had been infected). In Taiwan, of vaccinated babies born to HBV positive mothers, the proportion of those that responded to vaccination varied between will usually result in an acute infection and viral clearance. An associated problem with HBV, in the South Pacific, is the hepatitis delta virus (HDV). HDV is a satellite viroid-like RNA virus that requires HBV for replication. It can either co-infect with, or super-infect upon HBV infection resulting in acute infection and/or chronic infection respectively.     

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。