Yen-Hsuan Ni

Hepatitis B Virus Infection in Children and Adolescents in a Hyperendemic Area: 15 Years after Mass Hepatitis B Vaccination

Hepatitis B virus (HBV) infection is an important cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma in many parts of the world, including Taiwan (1, 2). Up to 15% to 20% of the general population in Taiwan are chronic carriers of hepatitis B surface antigen (HBsAg) (3, 4). Most chronic carriage of HBV results from infection in early childhood, especially before 2 years of age (57). Taiwan launched the worlds first nationwide universal vaccination program in 1984 to prevent infection in the early years of life (8). In addition to decreasing the proportion of carriers and the prevalence of HBV infection in the current young generation (9), the universal vaccination program has also resulted in a decreased incidence of childhood hepatocellular carcinoma (10). To study the effect of this universal vaccination program, we conducted a series of prospective seroepidemiologic surveys in Chung-Cheng District, Taipei City, Taiwan. The first survey was conducted shortly before the mass vaccination program began in 1984 (6), followed by similar surveys in 1989 (11) and 1994 (12). We report findings that extend our follow-up observations to 199915 years after the start of the program. Methods National Vaccination Program The national program of universal HBV vaccination in Taiwan began on 1 July 1984 (8). At that time, only the newborn infants of mothers who were HBsAg carriers were vaccinated. The vaccination program was extended in June 1987 to include all newborn infants and in July 1987 to cover all children of preschool age. The program was further extended to school children, teenagers, and then adults from 1988 to 1990. Since 1991, the vaccination records of first-grade children have been checked, and children without a complete set of previous vaccinations have been given catch-up HBV vaccinations. Before July 1992, four doses of plasma-derived vaccine were administered in children before 1 week of age and again at 1, 2, and 12 months of age; after July 1992, three doses of recombinant (yeast-derived) vaccine were administered before 1 week and at 1 month and 6 months of age. Since 1984, newborns whose mothers test positive for hepatitis B e antigen (HBeAg) have also received hepatitis B immunoglobulin, 0.5 mL (100 IU), within 24 hours after birth. The vaccination program has been described in greater detail elsewhere (8, 12). We defined the vaccination coverage rate as the percentage of children receiving at least three doses of HBV vaccine. We assessed the vaccination histories of the studied population by examining their vaccination cards and by taking a history from their parents. We classified the vaccination status as unknown for persons with a missing vaccination card or a vague vaccination history. Participants From March 1999 to October 1999, serum samples were collected from 1916 children and adolescents from two groups: 1) 1357 apparently healthy persons younger than 15 years of age [721 male participants and 636 female participants], who were born after the launch of the universal vaccination program, and 2) 559 persons (297 male participants and 262 female participants) 15 to 20 years of age, who were born before universal vaccination. We recruited participants for the baseline and follow-up seroepidemiologic studies in Chung-Cheng District, Taipei City. In 1999, Chung-Cheng had a population of 165 388 citizens; 35 005 of the citizens were younger than 15 years of age, and 47 565 were younger than 20 years of age. From 1994 to 1999, the population was stable, with an average annual migration rate of less than 4.8%. The annual family income,

Waning immunity to plasma-derived hepatitis B vaccine and the need for boosters 15 years after neonatal vaccination

39 963 (in U.S. dollars), was the third highest among the 12 districts in Taipei (13). From 1985 through 1990, the HBsAg carrier rate among pregnant women14% (14)was similar to the national average (3, 4). The 1916 participants in our 1999 study consisted of 1) 157 children younger than 3 years of age enrolled from the Well-Baby Clinic of the National Taiwan University Hospital Department of Pediatrics and from two day care centers; 2) 232 children 3 to 6 years of age recruited from two kindergarten classes; 3) 763 children 7 to 12 years of age enrolled from one public elementary school; 4) 205 children and adolescents 12 to 15 years of age enrolled from one public junior high school; 5) 219 adolescents 15 to 18 years of age enrolled from one high school; and 6) 340 first-year undergraduate students at the National Taiwan University, 19 to 20 years of age. We recruited the child and adolescent participants through poster advertisements and by invitation from the health staff of the Department of Pediatrics, National Taiwan University Hospital. The university student participants and the parents of enrolled children gave written, informed consent and provided the vaccination history of the participant, according to his or her personal health booklet. (The booklet, which is used to record a persons vaccination history, is provided to the parents of all newborns by the Health Bureau of City Hall.) Serologic and Statistical Analyses We analyzed serum samples for HBsAg, HBsAg antibody (anti-HBs), and hepatitis B core antibody (anti-HBc) by using enzyme immunoassay (Abbott Laboratories, North Chicago, Illinois). We examined between-group differences in frequency by using the chi-square test with Yates correction or the Fisher exact test, where appropriate. A P value less than 0.05 was considered significant. Data analyses were performed by using GraphPad Prism, version 3.00 (GraphPad Software, Inc., San Diego, California). Role of the Funding Source The funding source had no role in the collection, analysis, and interpretation of the data or in the decision to submit the paper for publication. Results In 1999, the vaccination coverage rate was greater than 90% among children younger than 8 years of age and 80% to 86% among children 8 to 15 years of age (Table). These figures might be underestimates because some of the participants, particularly in the older age group, had missing vaccination cards; in other cases (for 23 of the 541 children younger than 8 years of age and 63 of the 766 participants 8 to 15 years of age), the parents could not recall the vaccination history. Infants had a lower coverage rate than other age groups because some of them had not yet finished their vaccination schedule (Appendix Table). Table. Seroprevalence of Hepatitis B Surface Antigen and Its Antibody in Chung-Cheng District, Taipei City, Taiwan, in 1984, 1989, 1994, and 1999 The prevalence of HBsAg in children younger than 15 years of age, 0.7% (9 of 1357), was considerably lower than the rate of 7% (39 of 559) observed in participants older than 15 years of age, who were born before the universal vaccination program (P < 0.001). Of the 9 children who were born after the vaccination program was instituted and tested positive for HBsAg, only 1 had not received the scheduled vaccinations, and the mother of this child was also HBsAg positive. According to their vaccination cards, the 8 other participants had received at least three doses of the HBV vaccine, and the first dose had been given within 1 week of birth. Seven of these 8 participants had mothers who were HBsAg carriers, and the remaining participant was living with two grandparents who were HBsAg positive. All 9 participants tested positive for anti-HBc. Eight of these 9 HBsAg carriers had received the plasma-derived vaccine, and 1 had received the yeast-derived recombinant vaccine; however, type of vaccine did not affect the rate of HBsAg seropositivity (8 of 968 persons who received the plasma-derived vaccine were carriers vs. 1 of 389 who received the yeast-derived vaccine; P > 0.2, Fisher exact test). The overall prevalence of anti-HBs in persons younger than 15 years of age in 1999 was 75.8%. We observed the highest prevalence of anti-HBs in children younger than 5 years of age (Table). The longitudinal perspective of HBsAg carriers in cohorts 0 to 1 years of age is shown in the Figure. Figure. Longitudinal perspective of the proportion of hepatitis B surface antigen carriers among the cohorts of 0 to 1 year of age in 1984 (circles) and 1989 (squares) in Chung-Cheng District, Taipei City, Taiwan. Children in the 1984 0- to 1-year age cohort, who were born before universal vaccination in Taiwan, had a carrier rate of 5.1% in 1984, 3.9% in 1989 (at age 5 to 6 years), 4.7% in 1994 (at age 10 to 11 years), and 7.5% in 1999 (at age 15 to 16 years). These proportions are significantly higher than those observed over time in the 1989 0- to 1-year age cohort, who were born since the national vaccination program started, at the corresponding age points (from the survey years 1989, 1994, and 1999, respectively). The rate of anti-HBc seropositivity was 2.9% in persons younger than 15 years of age but was 20.6% in persons 15 years of age or older (P < 0.001). In contrast, the rate of anti-HBc seropositivity among children younger than 15 years of age was 26.2% in 1984 (6), 14.5% in 1989 (11), and 4.0% in 1994 (12). Discussion The prevalence of HBsAg among children younger than 15 years of age decreased from 9.8% to 0.7% in the 15 years since implementation of the universal vaccination program. A high coverage rate for HBV vaccination is crucial for decreasing the prevalence of HBV infection. We observed a vaccination rate of at least 80% among children younger than 15 years of age and as high as 97% among children 4 years of age or younger. A nationwide series of seroepidemiologic studies of three cohorts of children 6 years of age in 1989, 1991, and 1993 reported that the vaccination rates for HBV ( 3 doses of vaccine) were 27.8%, 60.7%, and 88.7%, respectively (9). The age of these three cohorts in 1999 correspond to the age groups of 15 to 18 years, 13 to 14 years, and 11 to 12 years in our study. The data from these three national cohort studies confirm that the vaccination rate in our sample is similar to the vac

Absence of infection in breast-fed infants born to hepatitis C virus-infected mothers

Neonatal immunization with hepatitis B (HB) vaccine is highly effective; however, more needs to be learned about the duration of protection and indications for boosters. We measured antibody to HB core antigen (anti‐HBc), HB surface antigen (HBsAg), and pre‐ and postbooster titers of HBsAg antibody (anti‐HBs) 15 years after primary neonatal immunization with plasma‐derived HB vaccines in 2 cohorts of 15‐year‐old children. Group A consisted of 78 children who were born to HB e antigen–positive HBsAg carrier mothers and had developed protective levels of anti‐HBs antibodies (≥10 mIU/mL) following HB immunization. Group B consisted of 113 apparently healthy children whose anti‐HBs titers after vaccination were unknown. Anti‐HBs was undetectable (antibody titer <10 mIU/mL) in 29.9% in group A and 62.4% in group B (P < .001). Anti‐HBc was detected in 33.3 % in group A and 4.4 % in group B (P < .001). After a single booster dose of HB vaccine, 2.7% in group A and 3.3% in group B remained anti‐HBs–negative. A blunted serological response was noted in approximately 20% in both groups. One HBsAg carrier was detected in group A (1.3%) and 4 in group B (3.5%). Fifteen years after neonatal immunization with plasma‐derived HB vaccine, a large proportion of children exhibited waning immunity. This poses the risk of breakthrough infection. A single booster augmented the serological response to the vaccine in most but not all subjects. In conclusion, our findings suggest that one or more booster immunizations are needed in seronegative subjects by at least 15 years following neonatal immunization with plasma‐derived HB vaccine. (HEPATOLOGY 2004;40:1415–1420.)

Survey of hepatitis B surface variant infection in children 15 years after a nationwide vaccination programme in Taiwan

The role of breast-feeding in perinatal transmission of hepatitis C virus (HCV) was explored in 15 HCV-infected mothers and their infants. The 15 carrier mothers had anti-HCV titers ranging from 1:80 to 1:40,000 and also had HCV-ribonucleic acid with concentrations ranging from 10(4) to 2.5 x 10(8) copies/ml. Both anti-HCV antibody and HCV-ribonucleic acid were present in colostral samples in much lower levels, but none of the 11 breast-fed infants had evidence of HCV infection for up to 1 year of age. Thus breast-feeding seems safe for these infants.

Humoral and Cellular Immune Responses to a Hepatitis B Vaccine Booster 15–18 Years after Neonatal Immunization

Background: It is not known whether hepatitis B virus (HBV) with mutations in the a determinant (amino acids (aa) 121–149) of the hepatitis B surface antigen (HBsAg) affect vaccination efficacy. Aim: To investigate the prevalence and clinical significance of these mutants in children, 15 years after universal vaccination in Taiwan. Methods: Nucleotide sequences encoding the a determinant region (aa 110–160) of HBsAg were analysed in all HBV-DNA positive sera from 1357 children and 219 adolescents serosurveyed in 1999. We then compared the prevalence and changes in the mutants in these children with our previous surveys in the same area conducted in 1984 (just before vaccination), 1989, and 1994. Results: The prevalence of a determinant mutants in HBV-DNA positive children was 7.8% (8/103) in 1984, which significantly increased to 19.6% (10/51) in 1989, peaked at 28.1% (9/32) in 1994, and remained at 23.1% ((3/13) (T131I, G145R, G145R)) in 1999; it was higher in those fully vaccinated compared with those not vaccinated (15/46 v 15/153; p<0.001). However, the number of mutant infected children in each survey was stable in the first 5–10 year period but decreased 10–15 years post vaccination. Increased amino acid variation in the a determinant region occurred in carrier children in the post vaccination survey. Mutated residues tended to occur more frequently in the region with greater local hydrophilicity (residues 140–149) in those vaccinated than in unvaccinated children with variant infection (12/15 v 6/15; p = 0.062). More HBsAg positive a determinant mutants emerged in children fully vaccinated with plasma derived vaccine than those given recombinant vaccine (10/2399 (0.46%) v 0/503; p = 0.122). Conclusion: We found that a determinant variants have an advantage in infecting immunised children but do not threaten current HBV vaccination strategies in Taiwan.

Effects of Maternal Screening and Universal Immunization to Prevent Mother-To-Infant Transmission of HBV

BACKGROUND Whether hepatitis B (HB) vaccine-conferred immunity persists into adulthood is unknown. We aimed to investigate long-term HB immunity in adolescents. METHODS In 2004-2005, 6156 high school students (15-21 years old) who had been vaccinated with plasma-derived HB vaccine as infants were recruited for HB seromarker screening. The immune response to an HB vaccine booster was evaluated in 872 subjects who were seronegative. HB surface antibody (anti-HBs) titers and levels of HB surface antigen (HBsAg)-specific interferon (IFN)-gamma- or interleukin (IL)-5-secreting peripheral blood mononuclear cells (PBMCs; measured by enzyme-linked immunospot assay) were determined 4 weeks later. RESULTS Although the vaccine remained highly efficacious in reducing the HBsAg positivity rate, 63.0% of the vaccinees had no protective anti-HBs. After the booster, anti-HBs remained undetectable in 28.7% (158/551) of the subjects who had received complete HB vaccination (4 doses) during infancy. We estimated that 10.1% of the total population had lost their HB vaccine-conferred booster response. HBsAg-specific IFN-gamma- or IL-5-secreting PBMCs remained negative in 27.2% (25/92) of subjects after the booster. CONCLUSIONS A notable proportion of fully vaccinated adolescents had lost immune memory conferred by a plasma-derived HB vaccine 15-18 years later. This decay of immune memory may raise concerns about the need for a booster vaccine for high-risk groups in the long run.

Prevention of Hepatocellular Carcinoma by Universal Vaccination against Hepatitis B Virus: The Effect and Problems

BACKGROUND & AIMS Mother-to-infant transmission is the major cause of hepatitis B virus (HBV) infection among immunized children. There has been much debate about screening pregnant women and administering hepatitis B immunoglobulin (HBIG) to newborns. We analyzed the rate of HBV infection among children born to hepatitis B surface antigen (HBsAg)-positive mothers and whether HBIG administration reduces transmission. METHODS We analyzed data from 2356 children born to HBsAg-positive mothers, identified through prenatal maternal screens. In addition to HBV vaccines, HBIG was given to all 583 children with hepatitis B e antigen (HBeAg)-positive mothers and to 723 of 1773 children with HBeAg-negative mothers. Serology tests for HBV were performed from 2007 to 2009, when children were 0.5-10 years old. RESULTS A significantly greater percentage of children with HBeAg-positive mothers tested positive for antibodies against the hepatitis B core protein (16.76%) and HBsAg (9.26%) than children with HBeAg-negative mothers (1.58% and 0.29%, respectively; P < .0001 and <.001). Among the HBV-infected children, the rate of chronicity also was higher among children with HBeAg-positive mothers than children with HBeAg-negative mothers (54% vs 17%; P = .002). Similar rates of antibodies against the hepatitis B core protein (0.99% and 1.88%; P = .19) and HBsAg (0.14% and 0.29%; P = .65) were noted in children born to HBeAg-negative mothers who were or were not given HBIG. Infantile fulminant hepatitis developed in 1 of 1050 children who did not receive HBIG (.095%). CONCLUSIONS Children born to HBeAg-positive mothers are at greatest risk for chronic HBV infection (9.26%), despite immunization. Administration of HBIG to infants born to HBeAg-negative mothers did not appear to reduce the rate of chronic HBV infection, but might prevent infantile fulminant hepatitis. Screening pregnant women for HBsAg and HBeAg might control mother-to-infant transmission of HBV.

Host-microbial interactions and regulation of intestinal epithelial barrier function: From physiology to pathology

Purpose: In spite of the success of hepatitis B immunization, still a significant proportion of childhood hepatocellular carcinoma (HCC) failed to be prevented by the hepatitis B immunization program. This study is aimed to investigate the problems in the HCC prevention in children. Experimental Design: All HCC children ages 6 to 14 diagnosed between 1981 and 2000 in Taiwan were collected from two national childhood HCC registry systems. We analyzed the causes of HCC prevention failure and the risk ratio of HCC among hepatitis B carriers born before versus after the vaccination program. Results: The incidence of HCC per 100,000 children declined from 0.54 to 0.20 in those born before versus after the vaccination program (risk ratio, 0.36). Vaccine failure (33.3-51.4%) and failure to receive hepatitis B immunoglobulin at birth (42.4-57.5%) were the main causes of HCC prevention failure. Mother-to-child transmission of hepatitis B virus infection is an important risk factor of HCC development. This is evidenced by the very high hepatitis B surface antigen seropositive rate in our HCC children (97%) and their mothers (96%). Hepatitis B carrier children born after the vaccination program had a higher risk of developing HCC than those born before the program (risk ratio, 2.3-4.5). Conclusions: Vaccine failure and failure to receive hepatitis B immunoglobulin are the main problems preventing eradication of HCC. Hepatitis B carrier children born after the immunization program have a higher risk of developing HCC than those born before.

Long-Term Immunogenicity and Efficacy of Universal Hepatitis B Virus Vaccination in Taiwan

The gastrointestinal tract is the largest reservoir of commensal bacteria in the human body, providing nutrients and space for the survival of microbes while concurrently operating mucosal barriers to confine the microbial population. The epithelial cells linked by tight junctions not only physically separate the microbiota from the lamina propria, but also secrete proinflammatory cytokines and reactive oxygen species in response to pathogen invasion and metabolic stress and serve as a sentinel to the underlying immune cells. Accumulating evidence indicates that commensal bacteria are involved in various physiological functions in the gut and microbial imbalances (dysbiosis) may cause pathology. Commensal bacteria are involved in the regulation of intestinal epithelial cell turnover, promotion of epithelial restitution and reorganization of tight junctions, all of which are pivotal for fortifying barrier function. Recent studies indicate that aberrant bacterial lipopolysaccharide-mediated signaling in gut mucosa may be involved in the pathogenesis of chronic inflammation and carcinogenesis. Our perception of enteric commensals has now changed from one of opportunistic pathogens to active participants in maintaining intestinal homeostasis. This review attempts to explain the dynamic interaction between the intestinal epithelium and commensal bacteria in disease and health status.

Mother-to-infant transmission of hepatitis B virus infection: Significance of maternal viral load and strategies for intervention

The long-term immunogenicity of universal hepatitis B virus (HBV) vaccine is seldom studied in large-scale prospective community-based populations, especially in adolescents. This study enrolled 1200 children aged 7 years with complete HBV immunization in infancy and determined HBV surface antigen (HBsAg), its antibody (anti-HBs), and HBV core antibody (anti-HBc) annually until the children were aged 14 years. Eleven children had new HBV infections with anti-HBc positivity as the only marker. None became positive for HBsAg or had detectable HBV DNA by polymerase chain reaction. The percentage of protective anti-HBs in 951 children without booster vaccination gradually decreased from 71.1% at age 7 years to 37.4% at age 12 years. Only 1 of the 200 children in the booster group and 2 of the 258 children in the nonbooster group developed new anti-HBc positivity. The results suggest that routine booster vaccination may not be required to provide protection against chronic HBV infection before age 15 years.