Hepatitis A booster vaccine in children after infant immunization

BACKGROUND: Hepatitis A vaccine provides long term protection against hepatitis A infection in adults and children older than 2 years of age. Few data are available regarding children younger than 2 years of age. METHODS: Children who were vaccinated in infancy with hepatitis A vaccine were revaccinated at 4 years of age, and antibody titers were followed. Forty-four subjects who had been vaccinated with hepatitis A vaccine [Havrix, 360 enzyme-linked immunosorbent assay units (EU)] at the age of 2, 4 and 6 months were revaccinated with 720 EU of inactivated hepatitis A vaccine (Havrix) at 4 years of age. RESULTS: Geometric mean titer (GMT) of 44 evaluable cases was 41 mIU/ml and 34 children (77.3%) were seropositive before the booster dose. Postvaccination blood samples were obtained from 37 cases. One month after booster dose GMT increased to 2884 mIU/ml, and all subjects were seropositive. Ten seronegative cases also seroconverted. The GMT of the seropositive cases showed anamnestic response after the booster dose (57 mIU/ml before booster dose, 5623 mIU/ml after the booster). No serious adverse event was seen after the booster dose. CONCLUSION: We conclude that childhood hepatitis A virus revaccination after infant immunization is highly immunogenic and safe.     

Clinical trial to evaluate immunogenicity and safety of inactivated hepatitis A vaccination starting at 2-month-old children

Active immunization with hepatitis A vaccine has been shown to provide long-term protection against hepatitis A virus (HAV) infection. However, few data are available regarding use of the hepatitis A vaccine in children under two years of age. The present study was conducted to test the safety and immunogenicity of inactivated hepatitis A vaccine administered to infants, and to evaluate the correlation between mother and infant anti-HAV antibodies. A total of sixty healthy children, two months of age, were enrolled in this study and immunized with 360 EU of inactivated hepatitis A vaccine (Havrix) according to the two, four and six months of age schedule. Blood sampling was performed prior to the first vaccination and one month after the third vaccination at seven months. Venipuncture was also done on mother on admission. The reactogenicity was expressed as the percentage of reported local and systemic reactions. The most common side effects were erythema on the injection site and fever. Infants with passively transferred maternal anti-HAV antibodies had a reduced anti-HAV GMT after vaccination. On admission, only one infant and his mother were seronegative and seroconversion was only detected in this infant. One month after the third dose seven infants (12.3%) were found to be seronegative. The infant without passively acquired maternal anti-HAV had the protective levels with a GMT of 3176 mIU/ml one month following the third dose. There was a significant positive correlation between the titers of mother and infant anti-HAV antibodies (n = 0.96, p < 0.001) on admission. Hepatitis A vaccine showed no immunogenicity in infants with presence of maternal antibodies. Hepatitis A vaccine is safe but it should be used after the disappearance of maternal antibodies.     

Immunogenicity and reactogenicity of two recombinant hepatitis B vaccines in small infants: a randomized, double-blind comparative study

Hepatitis B infection is very common in infants, especially in countries with limited resources. Hepatitis B vaccination is recommended in the routine immunization schedules in many countries, including India. We compared immunogenicity and reactogenicity of two recombinant hepatitis B (HB) vaccines in healthy infants. A total of 262 evaluable Indian infants received three doses of 10 microg of an Indian (GeneVac-B) or European (Engerix-B) HB vaccine in a double-blind, randomized fashion. The first dose, given at birth, was followed by a dose at age 6 and 14 weeks. All the subjects were initially seronegative for HB surface antigen (HBsAg) and anti-HB antibodies (anti-HBs). The post-vaccination anti-HBs titers were assessed by ELISA at the time of second and third dose, and 1 month after the third dose. Seroconversion and seroprotection were defined as anti-HBs titers > or =1 mIU/ml and > or =10 mIU/ml, respectively. After first dose, the seroconversion rates were 20% and 17%, in Indian and European vaccine recipients, respectively. The second and third dose increased the seroconversion to 84% and 80%, and to 98% and 98%, respectively. Correspondingly, the seroprotection rates after the first dose was 11% and 10%, and consequently 54% and 58%, and 97% and 95%. None of the differences between vaccines reached statistically significant proportions. Geometric Mean Titer after third dose was 383 mIU/ml and 285 mIU/ml, respectively, also this difference remaining insignificant. Adverse events were similar in both vaccine groups. Immunogenicity and reactogenicity of the Indian and European Hepatitis B vaccines were comparable, when immunization was started at birth.     

Hepatitis A vaccination of infants: effect of maternal antibody status on antibody persistence and response to a booster dose

BACKGROUND: Infants with passively transferred maternal antibody (PMA) to hepatitis A virus (HAV) have lower concentrations of antibody to HAV (anti-HAV) after vaccination. We examined the effect of PMA on persistence of anti-HAV and on immune memory. METHODS: We measured anti-HAV concentrations of 6-year-old children who had responded to a three dose hepatitis A vaccine series at ages 2, 4 and 6 months. Group 1 children were born to anti-HAV-negative women; Group 2 children had anti-HAV-positive mothers and PMA at 2 months of age. Children without detectable antibody at 6-year follow-up were offered a booster dose [360 enzyme-linked immunosorbent units (ELU)]. An anamnestic response was defined as a postbooster anti-HAV concentration of > or =400 mIU/ml. RESULTS: At follow-up, before the booster dose, Group 1 subjects had a higher geometric mean concentration (50 mIU/ml vs.18 mIU/ml, P = 0.007), and a larger proportion retained seroprotective concentrations of anti-HAV [21 of 31 (68%) vs.4 of 17 (24%)] compared with Group 2 subjects. The two stage antibody decline curves for the two groups from 8 months old to follow-up testing were parallel. An anamnestic response occurred in all (5 of 5) Group 1 and 67% (4 of 6) of Group 2 children. The geometric mean antibody concentrations after the booster were 1102 and 406 mIU/ml for Groups 1 and 2, respectively (P = 0.10). CONCLUSIONS: Infants with PMA who receive hepatitis A vaccine have significantly lower concentrations of anti-HAV 6 years later than infants with no PMA who receive hepatitis A vaccine. Immune memory may remain functional despite these lower anti-HAV concentrations.     

A two dose schedule for combined hepatitis A and hepatitis B vaccination in children ages one to eleven years

RATIONALE: A combined hepatitis A and B vaccine, Twinrix, containing at least 720 enzyme-linked immunosorbent assay units of hepatitis A antigen and 20 microg of hepatitis B antigen in the adult formulation and half those doses in the pediatric formulation, has been available in many countries since 1997. This vaccine is administered on a three dose schedule: 0, 1 and 6 months. A reduction in the number of doses would add convenience for the vaccinees and reduce administration-associated costs. We investigated the safety and immunogenicity profile of the adult formulation administered at 0 and 6 months in children ages 1 to 11 years. METHODS: A total of 237 children of both sexes were enrolled. Blood sampling was performed at 0 and 1, 2, 6 and 7 months. Seropositivity for anti-hepatitis A virus was defined as > or = 33 mIU/ml and seroprotection against hepatitis B virus as > or =10 mIU/ml. Data on solicited and unsolicited adverse events were collected on diary cards. RESULTS: The vaccine was well-tolerated in all subjects. At Month 7 all subjects had seroconverted for anti-hepatitis A virus antibodies with a high geometric mean concentration (11 543 mIU/ml). We observed a continuous increase in anti-hepatitis B surface antibody (anti-HBs) seroconversion rates and seroprotection rates until Month 6. After the second dose (Month 7), all subjects seroconverted for anti-HBs antibodies with a high geometric mean concentration (8056 mIU/ml) and 98.5% of the subjects were considered seroprotected. CONCLUSION: The two dose adult formulation could be an alternative to prevent hepatitis A and hepatitis B infection in children ages 1 to 11 years.     

Immunogenicity of single dose live attenuated hepatitis A vaccine

A long-term immunogenicity study of a single dose live attenuated H2 strain hepatitis A vaccine is being conducted in healthy Indian children at KEM Hospital, Pune. 131 of the original 143 children vaccinated in 2004, were evaluated for anti-HAV antibodies 30 months post vaccination (2007). Seroprotective antibody levels ≥20 mIU/mL were demonstrated in 87.8% subjects with an overall GMT of 92.02mIU/mL. No hepatitis like illness was recorded in any of the subjects since vaccination     

Hepatitis B vaccine in the EPI schedule

Objective : This study was carried out to evaluate the adequacy of seroconversion when Hepatitis B vaccine is given along with other vaccines at 0, 6 weeks (along with DPT and OPV) and at 9 months (along with measles).Methods: 725 infants born to apparently healthy mothers were enrolled to receive the hepatitis B vaccine at 0, 6 weeks and 9 months (Group A) or at 0, 1 and 6 months as per WHO schedule — (Group B). Baseline HbsAg testing was carried out and the babies were immunized with the first dose of hepatitis B vaccine within 48 hours of birth. BCG and the other EPI vaccines were given as per schedule. Serum samples were collected 4 weeks after the second and the third immunizations. 604 infants (83.3%) completed the study. The testing for HbsAg and Anti Hbs titers were conducted in the Department of Microbiology, Maulana Azad Medical College, New Delhi utilizing standard ELISA kits.Results: The seroconversion rates 4 weeks after the second dose of the vaccine were 90.89% (GMT = 48.23) and 91.82% (GMT = 43.95) (P=0.8) in Group A and Group B respectively. After 4 weeks of the third dose the seroconversion rates were 98.99 (GMT = 161.12) and 98.45 (GMT = 150.12) (p=0.17) in Group A and Group B respectively. The two schedules were comparable on using the Kruskal-Wallis H method for analysis.Conclusion : The schedule of hepatitis B vaccination at 0, 6 weeks and 9 months has the same seroefficacy as the currently recommended schedule of 0, 1 and 6 months.     

Hepatitis B Virus Infection and Vaccination in Children Undergoing Hemodialysis

ABSTRACT. Among 54 patients, between 2 and 18 years of age, submitted to hemodialysis due to severe chronic renal failure, the prevalence of hepatitis B virus markers was 66.7 % and that of HBsAg was 13.0 %. Eighteen children, with no evidence of hepatitis B virus infection, were vaccinated. Following three vaccine injections, only 2 patients did not respond and a third one developed low anti-HBs titers. The vaccine was well tolerated. No relationship was observed between the intensity of the humoral immune response and age, sex, type of renal disease and time on dialysis. Seroconversion rates (87.5 %) and geometric means of anti-HBs titers (>4 000 Ausab Units) of these patients are similar to those observed following vaccination of healthy adults.     

Immunogenicity and safety of a pediatric dose of a virosome-adjuvanted hepatitis A vaccine: a controlled trial in children aged 1-16 years

BACKGROUND: The availability of pediatric formulations of hepatitis A virus (HAV) vaccines would facilitate the introduction of universal mass vaccination against HAV. The objective of this study was to compare a pediatric dose (0.25 mL) of Epaxal, a virosomal, aluminum-free HAV vaccine, to 0.5 mL standard dose, and to alum-adsorbed HAV vaccine. METHODS: Subjects aged 1-16 years, stratified for age, were randomized (2:2:1) into group A (0.25 mL Epaxal), group B (0.5 mL Epaxal), or group C (Havrix Junior). Vaccines were administered at months 0, 6. Seroprotection rates (>or=10 mIU/mL anti-HAV antibodies) were assessed for noninferiority, defined as lower limit of 1-sided 97.5% CI >-10%. Incidence of local solicited adverse events and unsolicited adverse events were recorded. RESULTS: Mean age of 308 enrolled subjects was 8.9 years (range, 1.0-17.0 years). All 3 vaccines were highly immunogenic. Noninferiority of group A versus group B and group C with regard to seroprotection was demonstrated after both vaccine doses for the entire study group and for all age subgroups (11-23 months, 2-4, 5-7, 8-10, 11-13, 14-16 years). One month after first vaccination, geometric mean antibody concentrations were 69.0, 83.5, and 50.5 mIU/mL for the 3 groups, respectively (A versus B, P = 0.0208; A versus C, P = 0.0015). Local injection site pain occurred more frequently in group C than in groups A and B. No subjects withdrew from study or reported any vaccine-related serious adverse event. CONCLUSION: In children aged 1-16 years, 0.25 mL dose of Epaxal is as immunogenic as standard 0.5 mL dose and Havrix Junior. The aluminum-free vaccine compares favorably to comparator vaccine regarding local reactogenicity.     

Hepatitis B virus infection and vaccination in children undergoing hemodialysis

Among 54 patients, between 2 and 18 years of age, submitted to hemodialysis due to severe chronic renal failure, the prevalence of hepatitis B virus markers was 66.7% and that of HBsAg was 13.0%. Eighteen children, with no evidence of hepatitis B virus infection, were vaccinated. Following three vaccine injections, only 2 patients did not respond and a third one developed low anti-HBs titers. The vaccine was well tolerated. No relationship was observed between the intensity of the humoral immune response and age, sex, type of renal disease and time on dialysis. Seroconversion rates (87.5%) and geometric means of anti-HBs titers (greater than 4 000 Ausab Units) of these patients are similar to those observed following vaccination of healthy adults.     

Concomitant administration of a virosome-adjuvanted hepatitis a vaccine with routine childhood vaccines at age twelve to fifteen months: a randomized controlled trial

BACKGROUND: The objectives of this trial were to test for noninferiority of a virosomal hepatitis A virus (HAV) vaccine (Epaxal) coadministered with routine childhood vaccines compared with Epaxal given alone and to an alum-adjuvanted HAV vaccine (Havrix Junior) coadministered with routine childhood vaccines. METHODS: Healthy children 12- to 15-month-old were randomized to receive either a pediatric dose (0.25 mL) of Epaxal coadministered with DTPaHibIPV, oral polio vaccine, and measles-mumps-rubella vaccine (n = 109; group A), or Epaxal given alone (n = 105; group B), or Havrix Junior coadministered with DTPaHibIPV, oral polio vaccine, and measles-mumps-rubella vaccine (n = 108; group C). A booster dose was given 6 months later. Anti-HAV antibodies were tested before and 1 month after each vaccination. Safety was assessed for 1 month after each vaccination. Solicited adverse events were assessed for 4 days after each vaccination. RESULTS:: HAV seroprotection rates (> or =20 mIU/mL) at 1 and 6 months after first dose were: A: 94.2% and 87.5%, B: 92.6% and 80.0%, C: 78.2% and 71.3%, respectively (A versus C: P < 0.001 and P = 0.017 at month 1 and 6, respectively). The respective geometric mean concentrations were: A: 51 and 64 mIU/mL, B: 49 and 59 mIU/mL, C: 33 and 37 mIU/mL (A versus C: P < 0.001 at both time points). All groups achieved 100% seroprotection after the booster dose. The geometric mean concentrations after the booster dose were 1758, 1662, and 1414, for groups A, B and C, respectively (A versus C: P = 0.15). No clinically significant reduction in immune response to all concomitant vaccine antigens was seen. All vaccines were well tolerated. CONCLUSIONS:: Coadministration of pediatric Epaxal with routine childhood vaccines showed immunogenicity and safety equal to Epaxal alone as well as to Havrix Junior. After first dose, Epaxal was significantly more immunogenic than Havrix Junior.     

A combined vaccine against hepatitis A and B in children and adolescents

BACKGROUND: Pediatric monocomponent formulations of vaccines against hepatitis A and B have been proved to be safe and immunogenic in children. OBJECTIVES: To investigate the safety and immunogenicity of a combined hepatitis A/B vaccine in children 1 to 15 years of age. METHODS: Three doses of a combined vaccine containing 360 enzyme-linked immunosorbent assay units of hepatitis A antigen and 10 microg of hepatitis B surface antigen were administered in a 0-, 1-, 6-month schedule to three groups of children: a group of 1- to 6-year-olds (n = 60); and two groups of 6- to 15-year-olds (both n = 60). RESULTS: Reactogenicity, assessed using diary cards, was not affected by the age of the subjects or the vaccine lot and was similar to that described with the monocomponent vaccines. Local and systemic reactions were mostly mild or moderate and resolved spontaneously. One month after the second dose 100 and 98.8% of all three groups had seroconverted against hepatitis A virus and hepatitis B virus, respectively. After the third dose all subjects were seropositive for both components, with geometric mean titers for anti-hepatitis A virus of 6518 to 8907 mIU/ml and for anti-hepatitis B surface antibody of 7255 to 11732 mIU/ml in the three groups. CONCLUSION: The combined pediatric hepatitis A/B vaccine formulation was well-tolerated and highly immunogenic in children 1 to 15 years old.     

Effect of maternal antibody on immunogenicity of hepatitis A vaccine in infants

OBJECTIVE: To determine the effect of maternal antibody on hepatitis A vaccine immunogenicity in infants.Study design Infants of mothers negative for antibody to hepatitis A virus (anti-HAV; group 1) were administered hepatitis A vaccine at 2, 4, and 6 months of age, and infants of anti-HAV-positive mothers were randomized to receive either hepatitis A vaccine (group 2) or hepatitis B vaccine (group 3) on the same schedule. Group 3 infants subsequently received hepatitis A vaccine at 8 and 10 months of age. RESULTS: At 15 months of age, 100% of infants in group 1, 93% in group 2, and 92% in group 3 had protective levels of antibody. However, there were significant differences in the geometric mean concentration (GMC) of anti-HAV between groups. Group 1 GMC was 231 mIU/mL, compared with 85 mIU/mL for group 2 and 84 mIU/mL for group 3 (P<.001, group 1 vs group 3). CONCLUSIONS: Passively acquired maternal anti-HAV resulted in a significantly lower final antibody response when infants were administered hepatitis A vaccine at 2, 4, and 6 months of age or at 8 and 10 months of age.     

Interchangeability of a hepatitis A vaccine second dose: Avaxim 80 following a first dose of Vaqta 25 or Havrix 720 in children in Turkey

Introduction This randomised, observer-blind clinical trial conducted in Turkey evaluated the immunogenicity, safety and interchangeability of three paediatric inactivated hepatitis A vaccines in 424 seronegative children between 1 and 15 years of age. Methods Potential subjects were screened for anti-hepatitis A virus (HAV) antibodies prior to receiving a first dose of Avaxim 80, Havrix 720 or Vaqta 25, followed by a second dose of either the same vaccine or Avaxim 6 months later. Anti-HAV antibody concentrations were measured 2 weeks after the first injection, at 24 weeks (before the second dose) and at 28 weeks for the evaluation of the immune response. Results Nearly 80% of the children between 1 and 5 years of age and half of those between the ages of 6 and 10 in the population from which the subjects were recruited were seronegative for HAV antibodies. Two weeks after the first dose, 98.2% of all subjects had anti-HAV antibody concentrations equal to or higher than 20 mIU/mL, believed to be seroprotective, and all subjects were seroprotected before and after the second dose. Anti-HAV geometric mean concentrations (GMCs) 2 weeks after the first dose and before the second were similar in children who received Avaxim and Vaqta (P = 0.2), but both were higher than Havrix (P < 0.01). There were no significant differences in the anti-HAV GMCs between the study groups that received two doses of the same vaccine compared with two doses of different vaccines. There were no significant differences in the frequency of any local or systemic adverse events among the study groups following either of the two doses. Conclusion All three vaccines are safe and highly immunogenic in healthy children aged 1 to 15 years. Avaxim 80 may also be given as the second dose when Havrix 720 or Vaqta 25 are given as the first dose. The pattern of seroprevalence seen here is similar to that reported in a number of recent evaluations in Turkey, and are supportive of the routine hepatitis A vaccination of young children.     

Long-term immunogenicity and immune memory after two doses of the adult formulation of a combined hepatitis A and B vaccine in children 1 to 11 years of age

Long-term persistence of antibodies against hepatitis A and B (anti-HAV and anti-HBs) were evaluated in 1- to 11-year-old children following 2 doses (0, 6 months) of hepatitis A and B vaccine. Ten years postvaccination, all subjects were anti-HAV seropositive (≥15 mIU/mL), 81.7% had anti-HBs antibody concentrations ≥10 mIU/mL. All subjects with anti-HBs concentrations <10 mIU/mL, mounted a vigorous anamnestic response to an HBV vaccine challenge dose indicating the presence of immunologic memory against hepatitis B.     

Hepatitis A vaccination in chronic carriers of hepatitis B virus.

Because hepatitis A infection may be more severe in patients with chronic liver disease, we vaccinated 33 children who were chronic HBsAg carriers against hepatitis A virus. Anti-hepatitis A virus seroconversion rates after the first, second, and third doses were 90.9%, 96.9%, and 100%, respectively.     

Role of hepatitis B immunoglobulin in infants born to hepatitis B e antigen-negative carrier mothers in Taiwan

BACKGROUND: The efficacy of hepatitis B immunoglobulin (HBIG) in infants of hepatitis B e antigen (HBeAg)-negative hepatitis B surface antigen (HBsAg) carrier mothers in Taiwan is not clear. OBJECTIVE: To describe the responses of infants born to HBeAg-negative carrier mothers receiving HBIG combined with hepatitis B vaccine. METHODS: Term babies born to HBeAg-negative carrier mothers were assigned based on chart number to 1 of the 2 treatment groups. Group A infants (n = 94) received 0.5 ml (145 IU) of HBIG within 24 h of birth and 3 subsequent doses of recombinant hepatitis B virus (HBV) vaccine at 3 to 5 days, 1 month and 6 months of age. Group B infants (n = 122) received 3 doses of vaccines only. Infants (n = 19) born to HBeAg-positive carrier mothers were treated like those in Group A and are referred to as Group C. Sera obtained from infants at 2 and 7 months of age were tested for hepatitis B virus (HBV) markers. RESULTS: There were 2 (1%; one in Group A and one in Group B) subclinical breakthrough hepatitis B infections among studied infants. One (5%) child of Group C had asymptomatic HBV infection at the age of 7 months and became a chronic carrier. The rate of protective anti-hepatitis B surface antibody (anti-HBs) titers achieved (>10 mIU/ml) by 2 months of age was significantly higher in Group A than that in Group B (98% vs. 57%, P < 0.001). However, it was not different by 7 months of age. Infants (Group A) immunized with HBIG and vaccine had a significantly higher geometric mean titer (GMT, milli-International Units/ml) of anti-HBs than those (Group B) with vaccines only at 2 months of age (P < 0.001). Conversely at 7 months of age, the GMT of anti-HBs was significantly higher in infants who received vaccine only (P = 0.001). CONCLUSIONS: A protective level of antibodies was achieved earlier in those infants receiving both passive and active immunizations. However, infants receiving active immunizations alone achieved a higher GMT at 7 months of age. There was no clear benefit of passive-active vs.active immunization alone for chronic HBV infection in infants of HBsAg-positive, HBeAg-negative mothers.     

Diminished antibody response to hepatitis B immunization in children with sickle cell disease

Hepatitis B surface antibody titers were routinely measured in 150 children with sickle cell disease (SCD) after immunization, and the seroconversion rate was found to be lower than that in the general population (89% vs. 97%, P = 0.002). Most of the children who did not seroconvert after the series of 3 immunizations responded to booster injections (93%). Therefore, we recommend the measurement of hepatitis B surface antibody titers after immunization in those children with SCD at greatest risk for hepatitis B infection. An additional dose of hepatitis B vaccine should be administered to those without evidence of seroconversion.     

Immunogenicity and safety of two doses of a paediatric hepatitis A vaccine in thai children: comparison of three vaccination schedules

As fewer children in Thailand are exposed to hepatitis A virus (HAV) and so do not have seroprotective anti-HAV antibodies, they are becoming an important source of HAV transmission. A flexible HAV vaccination schedule would facilitate incorporation of the vaccine into existing immunization programmes, and we compared the immunogenicity and safety of three HAV immunization schedules. An open, randomized, clinical trial was carried out in which healthy children were given a primary dose of the inactivated hepatitis A vaccine, Avaxim 80 paediatric, with a booster dose 6, 12 or 18 months later. Anti-HAV geometric mean concentrations (GMC), seroconversion rates, and GMC ratios (GMCR) of the three schedules were compared and reactogenicity was evaluated. Seroconversion rates were above 98 per cent (per group) up to the booster. The three schedules were equivalent in terms of GMCRs, each eliciting a large booster effect. Local reactions were reported for fewer than 9 per cent of each group after dose one and less frequently after the booster dose. Injection site pain, gastrointestinal tract disorders and fever were the most commonly reported adverse events. No vaccine-related serious adverse events were reported. It was concluded that the hepatitis A vaccine, Avaxim 80 paediatric, is safe and immunogenic when given as a two-dose schedule to healthy seronegative children aged 5-10 years, with the second dose given at either 6, 12 or 18 months after the first.     

Immunogenicity of inactivated hepatitis A vaccine in children with chronic liver disease

One and 6 months after vaccination with hepatitis A virus vaccine (HAVRIX 720 Junior), immunologic responses (anti-hepatitis A virus >/=20 mIU/ml) in children with chronic hepatitis C infection seroprotection were 92% (23/25) and 75% (9/12) in children with chronic hepatitis B infection 87% (21/24) and 88% (15/17) and in healthy children 91% (20/22) at both times. A booster dose induced seroprotection in all children.