Success of a program of routine prenatal screening for hepatitis B surface antigen: the first 2 years.

Prenatal screening for hepatitis B surface antigen (HBsAg) restricted to women with defined risk factors for chronic hepatitis B virus (HBV) infection fails to identify many carriers. A centralized program of routine HBsAg screening for all pregnant women in Alberta was introduced in 1985. We collected and analysed data for the first 2 years of the program in Edmonton to determine the frequency of risk factors for HBsAg positivity, the proportion of multiparous HBsAg-positive women not identified in previous pregnancies, the efficiency and cost-effectiveness of providing immunoprophylaxis to infants at risk of HBV infection and the degree of success in inducing adequate protection. A total of 149 women (158 pregnancies) were found to be HBsAg positive. Risk factors were readily ascertainable for 85% of the women; the remaining 15% would not have been identified through risk-selective screening. The most common risk factors were Oriental ethnic origin, history of hepatitis, jaundice or multiple transfusions of blood or blood products, and occupational exposure to blood. Although 86% of the multiparous HBsAg-positive women had risk factors, only 7% had been identified in previous pregnancies. The Alberta program appears to be cost-effective. We conclude that only routine prenatal screening will identify all infants at risk of perinatal HBV infection and that a comprehensive public health program involving central laboratories, private physicians and public health staff can be highly effective and efficient in protecting infants against hepatitis B.     

Epidemiologic features of hepatitis B virus infection in northern Labrador.

We studied the epidemiologic features of hepatitis B virus (HBV) infection in northern Labrador to determine the prevalence of the infection and to obtain a database to develop a vaccination strategy. The study population included seven communities in which five ethnic groups were represented: Inuit, Innu, mixed Inuit and European ancestry ("settler"), nonnative/nonsettler transient population ("white") and people of Innu-white or Innu-Inuit origin ("mixed"). Blood samples from 2156 people (62% of the area residents) were tested for antibody to HBV core antigen (anti-HBc), HBV surface antigen (HBsAg), HBV e antigen (HBeAg), anti-HBc IgM and antibody to the surface antigen (anti-HBs). The overall crude prevalence rate of HBV seromarkers was 14.7% and the HBsAg carrier rate at least 3.2%; the rates were highest for Inuit (26.4% and 6.9% respectively), followed by settler (10.0% and 1.9% respectively) and Innu (7.6% and 0.4% respectively); the white and mixed groups had the lowest overall rates (2.5% and 3.3% respectively). Although the overall prevalence rates were about the same for the two sexes, the HBsAg carrier rate was higher in males (male:female ratio 1.6:1.0). No HBV carriers were positive for HBeAg or anti-HBc IgM antibody. The rate of exposure to HBV was 4% for those below the age of 20 years and reached a peak for those aged 45 to 54 years (85% for Inuit, 40% for settlers and 37% for Innu). There was also a wide variation in the age-standardized prevalence rates (0% to 27.9%) among the ethnic groups in the seven communities surveyed.     

Correlation between Vertical Transmission of Hepatitis B Virus and the Expression of HBsAg in Ovarian Follicles and Placenta

Background

The aim of this study was to investigate the correlation between the expression of hepatitis B surface antigen (HBsAg) in human ovary and placenta and the vertical transmission of hepatitis B virus (HBV).

Methodology/Principal Fidnings

Ovarian and placental tissue specimens of pregnant women infected with HBV were collected during cesarean section and immunostained for HBsAg. The sera of the corresponding newborns were tested for HBV markers and HBV DNA. HBsAg was detected in 15 out of 33 (45%) placental tissues and was further detected in capillary endothelial cells in 4 specimens (26%), of which 3 (75%) corresponding infants were infected with HBV in utero. Out of the 33 ovarian tissues, 7 (21%) were positive for HBsAg, of which 2 (28%) showed HBsAg in ovarian follicles and the 2 corresponding infants (100%) had intrauterine HBV infection.

Conclusions/Significance

HBsAg expression in cells of the ovarian follicle or placental capillary endothelium signal a higher risk for intrauterine HBV infection.     

Occult hepatitis B virus infection among injecting drug users in the Central-West Region of Brazil

The prevalence of occult hepatitis B virus (HBV) infection was investigated in 149 hepatitis B surface antigen (HBsAg) negative injecting drug users (IDUs) in the Central-West Region of Brazil. Of these individuals, 19 were positive for HBV DNA, resulting in an occult HBV infection prevalence of 12.7% (19/149); six of these 19 individuals had anti-HBV core and/or anti-HBV surface antibodies and 13 were negative for HBV markers. All IDUs with occult hepatitis B reported sexual and/or parenteral risk behaviours. All HBV DNA-positive samples were successfully genotyped. Genotype D was the most common (17/19), followed by genotype A (2/19). These findings reveal a high prevalence of occult HBV infection and the predominance of genotype D among IDUs in Brazil''s Central-West Region.     

Hepatitis B virus surface and core antigens in the liver of primary hepatocellular carcinoma cases in Virginia

Zenker-fixed paraffin-embedded sections of biopsy liver tissue from 64 cases of primary hepatocellular carcinoma (PHC) were stained for hepatitis B surface antigen (HBsAg) and for hepatitis B core antigen (HBcAg) by histochemical and/or immunohistochemical techniques in a retrospective study. PHC arose in livers with postnecrotic cirrhosis in 30 (46.9%) cases. Controls included liver biopsy sections from 123 miscellaneous liver disorders and from 67 randomly selected autopsy specimens, none of which were known to be associated with hepatitis B virus (HBV) infection. HBsAg was detected in tumorous hepatocytes in only one of the 64 cases of PHC. HBsAg was identified in nontumorous hepatocytes of 8 (20%) of 40 specimens that contained adequate nontumorous liver tissue. All of these HBsAg positive cases of PHC were associated with cirrhosis. Thus HBsAg was detected in 8 (33.3%) of 24 cases of PHC with cirrhosis, but in none of the remaining 16 cases without cirrhosis. HBcAg was not detected in the hepatocytes of those HBsAg positive PHC cases tested. Our results suggest that HBV infection may successively lead to chronic hepatitis, cirrhosis and ultimately PHC.     

Hepatitis B in a hospital for the mentally subnormal in southern England.

The prevalence of hepatitis B viral (HBV) infection was assessed in 340 patients and 268 staff in a hospital for the mentally subnormal in Wessex. Hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen, antibody to HBsAg, e antigen (eAg), and antibody to eAg were used as markers of such infection. Forty patients and 10 staff had evidence of recent or current infection, while 149 patients and 50 staff had evidence of past infection. HBV markers were more common in mongols, epileptics, patients with cerebral palsy, and those of lower mental grades and reached a peak after 5-15 years of hospitalisation. eAg was detected in 12 out of 26 patients with HBsAg but in none of the four staff with HBsAg. Abnormal liver function values were found in 24 (60%) of the patients with recent or current HBV infection but in only 30 (19%) of those without HBV markers. Among the staff the prevalence of HBV markers correlated with the duration of employment and degree of contact with patients. Of those with recent or current infection, 4 (40%) had abnormal liver function values compared with 25 (12%) of those without HBV markers. Despite the high prevalence of markers clinically overt hepatitis B was rare.     

Occult hepatitis B demonstrated by anti-HBc and HBV DNA in HIV-positive patients

Background:

In patients who are hepatitis B virus (HBV) DNA-positive, but HBV surface antigen (HBsAg) -negative, the infection is referred to as occult hepatitis B infection (OBI). Occult HBV infection is harmful when other liver diseases are present, and can aggravate liver damage in in patients with chronic liver diseases. In human immunodeficiency virus (HIV) infection the suppression of viral replication by the immune system might be inactivated, and classical HBV infection in OBI patients may occur. Health care professionals should be aware of OBI in HIV patients. The routine test for HBV infection in Iran is the enzyme-linked immunosorbent assay for the HBV surface antigen (ELISA HBsAg); therefore, the aim of this study was to evaluate the prevalence of OBI in Iranian HIV patients.

Methods:

This cross-sectional study was conducted in 2012 on sera from all the known and accessible HIV patients in Jahrom and Fassa, two cities in southern Iran. All samples were tested for the HBsAg, HBV core antibody (HBcAb). All the results were analyzed using SPSS.

Results:

Of the 91 patients, seven (7.7%) were HBsAg-positive and forty-five (49.5%) were HBcAb-positive. In patients with negative HBsAg (84 patients), 39 (46.4%) were HBcAb positive and 53 (63%) were positive for HBV DNA.

Conclusion:

The prevalence of HBV infection is relatively high in HIV patients, and more accurate tests than those presently in use should be used for diagnosis.Key Words: Hepatitis B, HIV infection, Occult hepatitis     

Hepatitis B infection among patients attending a sexually transmitted diseases clinic in Rio de Janeiro, Brazil

Hepatitis B virus (HBV) has a low endemicity in Rio de Janeiro, Brazil. Sexual transmission must play an important role in this virus, but the prevalence and risk factors have never been properly investigated. The aim of this paper is to determine the prevalence and risk factors for HBV infection in patients attending a Sexually Transmitted Diseases Clinic of the Universidade Federal Fluminense, from the State of Rio de Janeiro, Brazil. In a retrospective study, HBV seroprevalence was investigated in 440 patients. Serum of each patient was assayed for antibodies against hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg) and antibodies against hepatitis B surface antigen (anti-HBs). Demographic and risk factor data were extracted from clinic notes. The overall seroprevalence of exposure markers for HBV (anti-HBc, HBsAg and anti-HBs) were 13%, 3.4% and 8.5% respectively. Homo/bisexual behaviour, anal intercourse, HIV infection, positive serology for syphilis and blood transfusion were predictors of the HBV exposure. Among demographic data, age and place of birth were associated with the anti-HBc seropositivity.     

Evaluation of the G145R Mutant of the Hepatitis B Virus as a Minor Strain in Mother-to-Child Transmission

The role of the hepatitis B virus (HBV) mutant G145R, with a single change in amino acid 145 of the surface protein, as a minor population remains unknown in mother-to-child transmission. The minor strain as well as the major strain of the G145R mutant were evaluated in three cohorts using a locked nucleic acid probe-based real-time PCR. The breakthrough cohort consisted of children who were born to HBV carrier mothers and became HBV carriers despite immnoprophylaxis (n = 25). The control cohort consisted of HBV carriers who had no history of receiving the hepatitis B vaccine, hepatitis B immunoglobulin or antiviral treatment (n = 126). The pregnant cohort comprised pregnant women with chronic HBV infection (n = 31). In the breakthrough cohort, 6 showed positive PCR results (major, 2; minor, 4). In the control cohort, 13 showed positive PCR results (major, 0; minor, 13). HBeAg-positive patients were prone to have the G145R mutant as a minor population. Deep sequencing was performed in a total of 32 children (PCR positive, n = 13; negative, n = 19). In the breakthrough cohort, the frequency of the G145R mutant ranged from 0.54% to 6.58%. In the control cohort, the frequency of the G145R mutant ranged from 0.42% to 4.1%. Of the 31 pregnant women, 4 showed positive PCR results (major, n = 0; minor, n = 4). All of the pregnant women were positive for HBeAg and showed a high viral load. Three babies born to 3 pregnant women with the G145R mutant were evaluated. After the completion of immunoprophylaxis, 2 infants became negative for HBsAg. The remaining infant became negative for HBsAg after the first dose of HB vaccine. G145R was detected in one-fourth of the children with immunoprophylaxis failure. However, the pre-existence of the G145R mutant as a minor population in pregnant women does not always cause breakthrough infection in infants.     

乙型肝炎病人重叠感染丙型肝炎的评价

应用ＥＬＩＳＡ和ＰＣＲ法检测５０２例乙肝病人血清,４０１例ＨＢｓＡｇ阳性血清中,有１１４例（２８．４％）抗－ＨＣＶ和ＨＣＶＲＮＡ双项阳性,２５例（６．２％）ＨＣＶＲＮＡ单项阳性;２１例（５．２％）抗－ＨＣＶ单项阳性。将ＨＢｓＡｇ乙肝病人分成ＨＢＶＤＮＡ,ＨＢｅＡｇ阳性组和ＨＢＶＤＮＡ,ＨＢｅＡｇ阴性组。前者抗－ＨＣＶ阳性率为１１．６％～２０．５％,ＨＣＶＲＮＡ阳性率为１６．２％～２０．５％。后者抗－ＨＣＶ阳性率为２０．２％～５５．６％,ＨＣＶＲＮＡ阳性率为２３％～６０．３％。结果说明长期携带ＨＢＶ者和慢性乙肝病人均可重叠ＨＣＶ感染。ＨＢＶＤＮＡ阳性组抗－ＨＣＶ和ＨＣＶＲＮＡ阳性率明显高于ＨＢＶＤＮＡ阳性组     

A seroepidemiologic study of hepatitis B virus infection among barbers in Huangshi City, Hubei, China

Between March and August 1986 in Huangshi City, serum samples were collected from 316 apparently healthy barbers as a study group, as well as from 361 healthy employees of department stores as a control group. They were tested for hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs) and antibody to hepatitis B core antigen (anti-HBc) by enzyme-linked immunoadsorbent assays. Barbers showed a prevalence higher than that in controls for HBsAg (16.8 vs. 9.2%, P less than 0.01), anti-HBs (67.1 vs. 45.9%, P less than 0.001), and anti-HBc (39.2 vs. 21.2%, P less than 0.001). The prevalence of at least one marker of hepatitis B virus (HBV) infection was significantly higher in barbers than in controls (86.1 vs. 61.7%, P less than 0.001). Although the socioeconomic status and education level did not correlate with the frequency of HBV markers, the prevalence of HBsAg increased in parallel with the duration of practice. Because of their high risk for HBV infection, barbers need to be screened for markers of HBV infection on a routine basis, and are prime candidates for immunoprophylaxis with hepatitis B vaccine.     

免疫预防阻断乙型肝炎病毒母婴传播效果的观察

阻断乙型肝炎病毒(HBV)母婴传播是控制乙型肝炎的重大问题。为探讨免疫预防对阻断HBV母婴传播的效果及影响因素,对667例HBV表面抗原(HBsAg)阳性孕妇及其婴儿进行研究。这些孕妇按HBVe抗原(HBeAg)和HBVDNA检测结果,分为HBeAg阳性组及阴性组、DNA阳性组及阴性组;按是否于孕晚期注射乙型肝炎免疫球蛋白(HBIG),分为注射组及未注射组。婴儿于出生24h内均肌内注射HBIG100IU,并按0、1、6方案注射10μg重组酵母HBV疫苗;8～12月龄后随访婴儿,并进行HBV标志物(HBV-M)检测。667个婴儿中,20例感染HBV,免疫阻断失败率为3.0%。孕妇HBeAg阳性组免疫阻断失败率为8.7%,阴性组为0.2%,两组差异显著(P<0.001);两组婴儿对疫苗免疫应答率分别为83.0%和83.1%,无显著差异(P=0.988)。孕妇DNA阳性组免疫阻断失败率为8.1%,HBVDNA均≥6log10copies/ml。孕期注射与未注射HBIG组婴儿免疫阻断失败率分别为3.7%和2.7%,无显著差异(P=0.479);两组婴儿对疫苗免疫应答率分别为84.4%和82.4%,无显著差异(P=0.519)。孕妇HBeAg阳性注射HBIG组与未注射组的免疫阻断失败率分别为8.4%和8.9%,无显著差异(P=0.892)。孕妇HBeAg阴性注射与未注射HBIG组的免疫阻断失败率分别为0.0%和0.3%,也无显著差异(P=0.538)。11例免疫阻断失败的婴儿中,10例出生时血清HBsAg已为阳性;8～12个月后随访,HBsAg仍持续阳性,提示为宫内感染。本研究证实,孕期注射HBIG未能提高婴儿对HBV疫苗加HBIG的免疫阻断效果。宫内感染可能是疫苗加HBIG免疫阻断失败的主要原因。采用降低孕妇血清HBVDNA的措施,如对孕妇进行抗HBV治疗,也许能降低HBV宫内感染率。     

Prevalence of hepatitis B viral markers in Vietnamese blood donors

Serum samples were assayed using radioimmunoassay in 573 Vietnamese blood donors living in Hano? (North Viet Nam). 66 (11.5%) subjects were HBsAg-positive. Of these 66 HBsAg carriers, 17 (25,8%) were positive for hepatitis B e antigen (HBeAg) and 43 (65.1%) for antibody to HBeAg (anti-HBe). 22 (3.8%) subjects were positive for antibody to hepatitis B core antigen (anti-HBc) alone. 402 (70.2%) subjects were positive for antibody to HBsAg (anti-HBs). This anti-HBs percentage increased with age. Only 83 (14.5%) subjects were negative for all hepatitis B viral (HBV) markers. This no HBV markers percentage decreased with age. The chi 2 test showed a non significant difference for frequencies of HBsAg, anti-HBc alone, anti-HBs but a significant one for frequencies of no HBV markers in men and women.     

Importance of markers of hepatitis B virus in alcoholic liver disease.

To determine the importance of the presence of serological markers of hepatitis B virus infection in patients with alcohol related liver disease we compared cumulative alcohol intake and clinical and histological features in patients with markers of hepatitis B virus infection and in those without. Hepatitis B surface antigen (HBsAg) was detected in five (2%) out of 285 patients studied and antibody to HBsAg (anti-HBs) in 41 (14%); one patient had antibody to hepatitis B core antigen alone. The combined prevalence of markers of hepatitis B virus infection was similar in patients with alcoholic cirrhosis (18%) and precirrhotic liver disease (13%). Two patients positive for HBsAg had histological features of both alcoholic liver disease and chronic active hepatitis, with stainable HBsAg. Patients with anti-HBs were, however, histologically indistinguishable from patients without markers, and the mean cumulative alcohol intake of patients with anti-HBs was similar to or even higher than that of patients with liver disease of comparable severity who had no evidence of previous infection. The presence of markers of hepatitis B virus infection was related to former residence in countries with a high prevalence of the infection and to previous parenteral treatment and blood transfusions. Infection with hepatitis B virus does not enhance the development of chronic liver disease in heavy drinkers, except in the small number who remain positive for HBsAg.     

潍坊市坊子区2012年产前HBsAg筛检及新生儿首针乙肝疫苗接种情况分析

目的：了解住院分娩产妇乙肝病毒表面抗原（ HBsAg）检测及其所生新生儿首针乙肝疫苗及时接种情况,为进一步完善新生儿乙型肝炎的免疫预防策略提供依据。方法对2012年坊子区设有产科的医院每月上报的产妇HBsAg 检测和新生儿首针乙肝疫苗接种资料进行分析。结果坊子区2012年设有产科的医疗机构共报告住院分娩产妇2975名,产前HBsAg筛检2881名,筛检率为96．84％,各医疗机构筛检率在96．55％和97．50％之间;检出HBsAg阳性者66例,阳性率为2．29％,各医疗机构阳性率在0．00％和5．52％之间。新生儿共2975名,其中常住者所生新生儿2612名,流动者所生新生儿363名,常住和流动的新生儿乙肝疫苗接种率分别为96．13％和94．21％,及时接种率分别为93．87％和90．36％,差异均无统计学意义（χ2＝2．98、3．67,P＞0．05）。122名未及时接种首针乙肝疫苗的新生儿系患各种疾病所致。结论坊子区2012年设有产科的医院对住院的孕产妇产前HBsAg筛查率较高,其所生的新生儿24 h内乙肝疫苗及时接种率较高。     

Rare Detection of Occult Hepatitis B Virus Infection in Children of Mothers with Positive Hepatitis B Surface Antigen

The prevalence of occult Hepatitis B virus (HBV) infection in children was considerably varied from 0.1–64% in different reports. In this study we aimed to investigate the prevalence of occult HBV infection among the children born to mothers with positive hepatitis B surface antigen (HBsAg) in Jiangsu, China. Serum samples were collected from 210 children of 207 mothers with positive HBsAg. HBV serological markers were detected by ELISA and HBV DNA was detected by nested PCR. Homology comparison of HBV sequences recovered from the child and mother was used to define the infection. Three children (1.43%) were positive for HBsAg, in whom the HBV pre S and S gene sequence in each child was identical to that in her mother. Of the 207 HBsAg-negative children, nine displayed HBV DNA positive by two nested PCR assays using primers derived from S and C genes. However, the sequence alignment showed that the sequences in each child were considerably different from those in his/her mother. Therefore, the sequences amplified from the children were very likely resultant from the cross-contaminations. Furthermore, the nine children with ‘positive HBV DNA’ were all negative for anti-HBc, and one had anti-HBs 3.42 mIU/ml and eight others had anti-HBs from 72 to >1000 mIU/ml, indicating that the nine children were less likely infected with HBV. Therefore, none of the 207 HBsAg-negative children of HBV-infected mothers was found to have occult HBV infection. We conclude that the prevalence of occult HBV infection in vaccinated children born to HBsAg positive mothers should be extremely low. We recommend that homology comparison of sequences recovered from the child and mother be used to define the occult HBV infection in children born to HBV infected mothers.     

Difference in the distribution of e antigen among different ethnic groups in a population of blood donors.

Sensitive techniques were used to detect e antigen and the corresponding antibody (anti-e) among 368 voluntary blood donors positive for hepatitis B surface antigen in the Montreal area and 310 people living in close contact with them. Neither e nor anti-e was found in the absence of markers of hepatitis B virus (HBV). Among the blood donors e antigen was detected in 23 and anti-e in 313, and 32 were negative for both markers. Of the 368 blood donors 330 were of French origin and 38 from other ethnic groups. The 23 e-positive subjects were unequally distributed among the ethnic groups: only 14 (4.2%) were recruited among the French group while 9 (23.7%) were recruited among other ethnic groups (P less than 0.001). This differences among ethnic groups might be related to the vertical or horizontal mode of dissemination of HBV infection.     

Risk of vertical transmission of hepatitis B virus in Tunisia

The risk of vertical transmission of hepatitis B virus (HBV) varies with type of viral endemicity, degree of maternal infection and genomic characteristics of the virus. The aim of this study is to estimate this risk in Tunisia using serological and molecular methods to evaluate HBV replication, to determine viral genotypes and to detect presence of occult hepatitis in 2709 pregnant women. Serological markers were detected by ELISA methods, Genotype was determined by PCR-RFLP and occult hepatitis by nested-PCR. Four percent of women were positive for HBsAg; only 3% of them were also positive for HBeAg. Viral replication, over than 10(3) copies/ml, was detected in 61% of positive HBsAg patients. Three viral genotypes were detected: D (95%), B (3%) and A (3%). Occult hepatitis was detected in 4% of sera with "anti-HBc isolated" profile. In conclusion, the risk of vertical transmission of HBV exists in Tunisia. It increases by frequency of precore mutants, predominance of the genotype previously associated with high levels of replication and possibility of occult hepatitis B. These results show the importance of screening by serological HBV markers systematically during pregnancy with evaluation of viral replication in order to prevent vertical risk by efficient tools.     

Prevalence of occult hepatitis B virus infection in kidney transplant recipients

In this cross-sectional study, 207 hepatitis B surface antigen (HBsAg)-negative kidney transplant recipients were evaluated based on demographic and epidemiological data and on the levels of serological markers of hepatitis B virus (HBV) and hepatitis C virus infection and liver enzymes. Patients with HBV or human immunodeficiency virus infection were excluded. Sera were analysed for the presence of HBV-DNA. HBV-DNA was detected in two patients (1%), indicating occult hepatitis B (OHB) infection (the HBV-DNA loads were 3.1 and 3.5 IU/mL in these patients). The results of the liver function tests were normal and no serological markers indicative of HBV infection were detected. The prevalence of OHB infection was low among kidney transplant recipients, most likely due to the low HBsAg endemicity in the general population of the study area.     

甘肃省1～59岁人群乙型肝炎病毒感染的血清流行病学调查

为了解甘肃省现阶段乙型肝炎病毒感染的现状,分析乙肝病毒感染血清学指标的变化,采用多阶段整群抽样的方法,抽取5个县区1~59岁人群共2200人进行调查。以ELISA方法对血清标本统一检测乙肝病毒表面抗原(HBsAg)、乙肝病毒表面抗体(抗-HBs)、乙肝病毒核心抗体(抗-HBc)。结果显示,甘肃省1~59岁调查人群HBsAg阳性率为3.59%,抗-HBs和抗-HBc阳性率分别为49.45%、16.33%;HBV总感染率为27.50%。比1992年HBV总感染率下降了36.48%,HBsAg阳性率下降了45.94%;1~4岁儿童HBsAg阳性率仅为1.13%,比1992年(5.34%)下降78.84%。甘肃省1~59岁人群乙肝病毒感染率下降,抗-HBs阳性率升高,尤其在1~4岁儿童变化更为明显;甘肃省乙肝感染逐步呈现由中高流行转向低流行区的趋势;乙肝疫苗免疫取得显著效果。