Anti-HBs responses in children vaccinated with different schedules of either plasma-derived or HBV DNA recombinant vaccine

Advances in management of end stage liver disease in children

End stage liver disease (ESLD) is an irreversible condition that is a management challenge to the paediatrician. The aetiology and natural history of ESLD in children is not only distinct from adults but also variable depending upon the age of presentation. Children are especially vulnerable to developmental delay, frailty and malnutrition. Nutritional support is the cornerstone of management of these children as it has a significant impact on the clinical course and survival, both before and after transplantation. Further, the complications of ESLD in children including but not limited to, ascites, portal hypertension, spontaneous bacterial peritonitis and encephalopathy raise unique management challenges. In this review we provide a concise review of and highlight recent advances in the management of paediatric ESLD.

Clinical Characteristics of Children With Celiac Disease Not Responding to Hepatitis B Vaccination in India

The immunological response to hepatitis B virus (HBV) vaccine may be suboptimal in children with celiac disease (CD), but the reasons for this are not well defined.

Objectives

This study was undertaken to assess the immune response to HBV vaccine in CD children and to explore the possible factors affecting the immune response.

Methods

The study population consisted of 3 groups-50 newly diagnosed CD children (group 1), 50 previously diagnosed CD children who were on gluten free diet (GFD) >3 months (group 2), and 100 age and gender matched healthy controls (group 3). The patient characteristics were recorded, and the blood samples were analyzed for HBsAg and anti-HBs titers. The nonresponders were given a booster dose of HBV vaccine and reevaluated after 6 weeks.

Results

Positive anti-HBs response was found in 46% in newly diagnosed CD children, 60% in CD children on GFD, and 83% in healthy controls (P < 0.001). The immune response to HBV vaccine in CD children was inferior to that in healthy children (53% vs 83%, P < 0.001). The immune response was found to be significantly affected by age at diagnosis, delay in diagnosis, type of presentation, and compliance to GFD. 44 out of 45 (97.77%) nonresponders from CD group seroconverted after a single booster dose.

Conclusion

Early diagnosis and good compliance to GFD may improve the immune response to HBV vaccine in CD children. Single additional booster dose is sufficient to attain optimal immune response.

From infancy and beyond… ensuring a lifetime of hepatitis B virus (HBV) vaccine-induced immunity

Despite the long-term efficacy and immune persistence observed following HBV vaccination of infants, the need for a booster dose following infant immunization continues to be deliberated. Evidence from HBV booster dose response studies and long-term immunization program reviews are the basis for the recommendation that a vaccine booster is not necessary. However, further studies continue to emerge and highlight the need for standardization among observational studies in order to appropriately compare outcomes. There is an assumption that neonatal and infant (within 12 months of age) vaccine immune responses are equivalent; however, evidence exists for distinct vaccine responses within the first year of life. HBV vaccine programs have evolved over time, particularly regarding the type and dosage of vaccine used. Several universal neonatal immunization programs initially incorporated a 2.5 μg dosage (Recombivax-HB, Merck). This dosage has been shown in multiple long-term studies and meta-analyses to be associated with a lower primary response, decreased antibody persistence over time, and a reduced booster response 10 to 20 years following immunization. Ongoing surveillance of this and other HBV neonatally-vaccinated populations, particularly in low endemic regions, is necessary to understand the impact on long-term protection in order to ensure lifelong protection against hepatitis B infection.

Hepatitis B immunization for indigenous adults, Australia

Objective

To quantify the disparity in incidence of hepatitis B between indigenous and non-indigenous people in Australia, and to estimate the potential impact of a hepatitis B immunization programme targeting non-immune indigenous adults.

Methods

Using national data on persons with newly acquired hepatitis B disease notified between 2005 and 2012, we estimated incident infection rates and rate ratios comparing indigenous and non-indigenous people, with adjustments for underreporting. The potential impact of a hepatitis B immunization programme targeting non-immune indigenous adults was projected using a Markov chain Monte Carlo simulation model.

Findings

Of the 54 522 persons with hepatitis B disease notified between 1 January 2005 and 31 December 2012, 1953  infections were newly acquired. Acute hepatitis B infection notification rates were significantly higher for indigenous than non-indigenous Australians. The rates per 100 000 population for all ages were 3.6 (156/4 368 511) and 1.1 (1797/168 449 302) for indigenous and non-indigenous people respectively. The rate ratio of age-standardized notifications was 4.0 (95% confidence interval: 3.7–4.3). If 50% of non-immune indigenous adults (20% of all indigenous adults) were vaccinated over a 10-year programme a projected 527–549 new cases of acute hepatitis B would be prevented.

Conclusion

There continues to be significant health inequity between indigenous and non-indigenous Australians in relation to vaccine-preventable hepatitis B disease. An immunization programme targeting indigenous Australian adults could have considerable impact in terms of cases of acute hepatitis B prevented, with a relatively low number needed to vaccinate to prevent each case.

Response to anti-HBV vaccine and 10-year follow-up of antibody levels in healthcare workers

BACKGROUND

Despite improvements in public health and antiviral treatments, vaccination is still the most effective means of prevention of hepatitis B virus (HBV) infection. However, little is known about the duration of protection given by the anti-HBV vaccine. Healthcare workers represent a category at risk not only of contracting infection but also of being a source of contagion to patients.

OBJECTIVES

To assess individual responses to the anti-HBV vaccine and duration of protection 10 years after its administration in a cohort of healthcare workers employed by the University Hospital 'G. Martino' in Messina, Italy.

METHODS

One hundred and seventy medical staff who had been vaccinated following an incident carrying risk of HBV infection were included in this study. The group was followed over a 10-year period, and HBV antibody levels were assessed using an automated microparticle enzyme immunoassay.

RESULTS

Protective antibody levels (≥10 mIU/ml) were found in 65% of subjects who had completed the full vaccine schedule (three doses) and in 35% of subjects who had only received one or two doses of anti-HBV vaccine. Moreover, 10 years after vaccination, HBV antibody levels were inversely related to age at vaccination (P < 0.001). No differences were found between males and females.

CONCLUSIONS

This study, in line with the literature, shows the importance of completing the full vaccine schedule (three doses). Moreover, in order to have an effective and durable antibody response and avoid the risk of contracting HBV after an injury at work, it is important to recommend anti-HBV vaccination at a young age, ideally during childhood in accordance with the national vaccination policy.

Effect of inclusion of hepatitis B vaccine in childhood immunization program in India: a retrospective cohort study

OBJECTIVE

To assess the effectiveness of hepatitis B immunization program in a field setting in India.

DESIGN

Serological survey of retrospective cohorts of children, vaccinated or not vaccinated with hepatitis B vaccine.

SETTING

Rural field areas of five districts in Andhra Pradesh state, where childhood hepatitis B immunization began in 2003.

PARTICIPANTS

Children aged 5-11 years who had received HB immunization (n=2674; 1357 boys) or not received such immunization (n=2350; 1236 boys).

MAIN OUTCOME MEASURES

Serum HBsAg, anti-HBc and anti-HBs (quantitative) using automated enzyme-immunoassays in the year 2010.

RESULTS

Anti-HBs positivity was higher among immunized than in unimmunized children (53% vs.18%; P<0.001), and anti-HBc positivity was lower (1.1% vs 10.8%: P<0.01). HBsAg positivity was low in both the groups (0.15% and 0.17%; P=0.855). Anti-HBs positivity rate declined with increasing age.

CONCLUSIONS

Administration of hepatitis B vaccine as part of Universal immunization program led to anti-HBs in a large proportion of children and a reduction in anti-HBc positivity, a marker of hepatitis B virus infection. These data provide evidence supporting efficacy of hepatitis B immunization program in an Indian field setting, justifying the decision to include it in the universal immunization program.

Determinants of Long-term protection after hepatitis B vaccination in infancy: a meta-analysis

BACKGROUND

The duration of protection after hepatitis B vaccination in early infancy is unclear and may be related to vaccination schedule, dosage, vaccine type and population characteristics. Factors potentially influencing waning immunity were assessed.

METHODS

A systematic review was performed. The main outcomes were prevalence of anti-hepatits B antibodies ≥ 10 mIU/mL after primary or booster vaccination. Factors potentially influencing protection were assessed in an adjusted random-effects meta-analysis model by age for both outcomes. Results of both meta-analyses were combined in a prognostic model.

RESULTS

Forty-six studies reporting on the anti-hepatits B antibodies ≥ 10 mIU/mL 5 to 20 years after primary immunization and 29 on booster response were identified. The adjusted meta-analyses identified maternal carrier status (odds ratio [OR]: 2.37 [1.11; 5.08]), lower vaccine dosage than presently recommended (OR: 0.14 [0.06; 0.30]) and gap time between last and preceding dose of the primary vaccine series (OR: 0.44 [0.22; 0.86]) as determinants for persistence of anti-hepatits B antibodies ≥ 10. A lower vaccine dosage was also associated with failure to respond to booster (OR: 0.20 [0.10; 0.38]). The prognostic model predicted long-term protection of 90% [77%; 100%] at the age of 17 years for offspring of noncarrier mothers vaccinated with a presently recommended dose and vaccination schedule.

CONCLUSIONS

Based on meta-analyses, predictors of waning immunity after hepatitis B vaccination in infancy could be identified. A prognostic model for long-term protection after hepatitis B vaccination in infancy was developed.

Hepatitis B vaccine in celiac disease: Yesterday, today and tomorrow

Some studies showed that in celiac patients the immunological response to vaccination is similar to that one found in general population except for vaccine against hepatitis B virus (HBV). The non-responsiveness to HBV vaccine has also been described in healthy people, nevertheless the number of non-responders has been demonstrated to be higher in celiac disease (CD) patients than in healthy controls. Several hypothesis explaining this higher rate of unresponsiveness to HBV vaccine in CD patients have been described, such as the genetic hypothesis, according with CD patients carrying the disease-specific haplotype HLA-B8, DR3, and DQ2, show a lower response to HBV vaccine both in clinical expressed CD patients and in healthy people carrying the same haplotype. On the other hand, it has been demonstrated that the gluten intake during the vaccination seems to influence the response to the same vaccine. Moreover, it has been demonstrated a possible genetic predisposition to hepatitis B vaccine non-responsiveness likely due to the presence of specific human leukocyte antigen haplotypes and specific single nucleotide polymorphism in genes of cytokine/cytokine receptors and toll like receptors, but the pathogenic mechanism responsible for this low responsiveness still remains unclear. The aim of this review is to focus on the possible pathogenic causes of unresponsiveness to HBV vaccine in CD patients and to propose an alternative vaccination schedule in order to improve the responsiveness to HBV vaccine in this at-risk patients.

Immunity to hepatitis B vaccine in Tanzanian under-5 children

BACKGROUND

Hepatitis B vaccine was introduced in Tanzania in 2002 and is administered as DPT-hepatitis B at 4, 8 and 12 weeks of life.

AIM

To determine immunity to hepatitis B virus in children under 5 years attending reproductive and child health (RCH) clinics.

METHODS

A cross-sectional, health facility-based study was conducted between July and December 2007 at Temeke, Amana and Mwananyamala municipal hospitals in Dar es Salaam, Tanzania. Children under 5 years who had received DPT-HB vaccine as evidenced by RCH card number 1 were included. Blood samples were collected to determine hepatitis B surface antigen (HB(s)Ag) and antibodies to hepatitis B surface antigen (anti-HB(s)) and hepatitis B core antigen (Anti-HB(c)). An anti-HB(s) level of > or =10 mIU/ml is regarded as protective. Nutritional and HIV status were also determined.

RESULTS

A total of 296 children under 5 years vaccinated with DPT-HB were recruited, 153 (51.7%) of whom were male. Altogether, 205 (69.3%) children had anti-HB(s) levels > or =10 mIU/ml. The number of DPT-HB vaccine doses, time interval since last DPT-HB dose and HIV status were significant predictors of anti-HB(s) levels. Five children (1.7%) were positive for HB(s)Ag, suggesting possible vertical transmission. No child had anti-HB(c) antibodies.

CONCLUSION

More than two-thirds of children under 5 years had protective anti-HB(s) levels. A change in the hepatitis B immunisation schedule to include a dose immediately after birth should improve immunity.

Mathematical model of the antibody response to hepatitis B vaccines: Implications for reduced schedules

One of the cardinal features of the immune response is immune memory: the size of the secondary antibody response to vaccination reflects the amount of immune memory that has been generated in an individual by the priming dose. We construct a mathematical model of the generation of immune memory and antibody in response to hepatitis B vaccines. The model predictions are compared to post-vaccination antibody titres from eight adult vaccine trials. The model demonstrates significant differences between different vaccines in both the time taken to generate immune memory and the amount of memory generated. The model provides theoretical support for the hypothesis that a single vaccine dose can generate protective immune memory.

Long-term efficacy of hepatitis B vaccine, booster policy, and impact of hepatitis B virus mutants

The long-term efficacy of hepatitis B vaccine, long-term effectiveness of hepatitis B immunisation programmes, immune memory induced by hepatitis B vaccine, current booster policies, and impact of hepatitis B virus mutants on immunisation programmes were reviewed at the Viral Hepatitis Prevention Board (VHPB) meeting in Sevilla, Spain, March 2004. The main focus was on universal vaccination programmes with data being presented from Italy, Saudi Arabia, Singapore, Spain, Taiwan, Thailand, The Gambia, and USA (Alaska).

Duration of hepatitis B immunity in low risk children receiving hepatitis B vaccinations from birth

BACKGROUND

The duration of protection after hepatitis B vaccination of infants is unknown.

METHODS

We determined antibody to hepatitis B surface antigen (anti-HBs) at 4-13 years of age in 363 low risk children who had been vaccinated starting at birth with hepatitis B vaccine. Those with nonprotective titers (<10 mIU/mL) received a booster dose. We similarly followed 16 children of hepatitis B surface antigen (HBsAg)-positive mothers.

RESULTS

Of low risk infants receiving a plasma-derived vaccine, 41% (42 of 102) of those whose primary response was unknown and 24% (4 of 17) who had initially responded retained protective titers (> or = 10 mIU/mL) of anti-HBs at 9 and 13 years, respectively. Of those who did not have protective antibody titers, 61% (33 of 54) and 67% (8 of 12), respectively, responded to a booster dose. In children of HBsAg-positive mothers, 31% retained protective anti-HBs at 12 years, and 90% (9 of 10) with nonprotective titers responded to a booster. In low risk children initially receiving a recombinant vaccine, 12.5% (26 of 208) and none (0 of 36) retained protective anti-HBs titers at 5 and 7 years of age, respectively. Of those who did not have protective titers, 90% (120 of 134) and 91% (32 of 35), respectively, responded to a booster.

CONCLUSIONS

Anti-HBs disappeared by 5 years of age in most children who were vaccinated with hepatitis B vaccine from birth. Although most children showed immunologic memory, one-third failed to demonstrate an anamnestic response to a booster dose. Additional long term studies of low risk infants are needed to determine duration of protection and the necessity for or timing of booster doses.

A liquid hexavalent combined vaccine against diphtheria, tetanus, pertussis, poliomyelitis, Haemophilus influenzae type B and hepatitis B: review of immunogenicity and safety

To reduce the number of injections needed to comply with paediatric vaccination requirements, a liquid, hexavalent vaccine (DTaP-IPV-PRP-T-HBs; Hexavac; Aventis Pasteur MSD) has been developed for primary and booster vaccination of infants and toddlers. In extensive clinical studies, Hexavac has been shown to be highly immunogenic. Seroconversion or seroprotective titres of antibodies against all antigens were achieved in the majority of infants following a primary series of three doses administered at 1-2-month intervals from 2 months of age. Hexavac also induced immunologic memory, as evidenced by the anamnestic response to booster vaccination at 12-18 months of age. These responses were comparable with those seen following concomitant administration of Pentavac (DTaP-IPV//PRP-T) and monovalent hepatitis B vaccine (H-B-Vax II), and were also within the ranges observed for other relevant licensed vaccines. Clinical studies comparing the immunogenicity of Hexavac administered at either 2, 3 and 4 months or 2, 4 and 6 months demonstrated that it can be used by either vaccination schedule. A further study also supported the use of primary doses of Hexavac at 3 and 5 months with a booster at 12 months of age. Hexavac demonstrated a good reactogenicity and tolerability profile. The most frequently reported adverse events after both primary and booster doses were local reactions of redness and swelling/induration and a systemic response of mild fever, irrespective of the vaccine used for priming. Hexavac provided immunity against six important childhood diseases with a single injection at each visit.

Intradermal vaccination of adults with three low doses (2 µg) of recombinant hepatitis B vaccine. II. Persistence of immunity and induction of immunologic memory

Of the 110 dentists who had presented seroconversion 50 days after the intradermal application of three 2 micrograms doses of the Belgian recombinant vaccine against hepatitis B (HB), administered eight years before at an interval of one month between the 1st and 2nd doses and of five months between the 2nd and 3rd doses, 51 were included for the assessment of the persistence of immunity. None of the dentists had hepatitis or had received HB vaccine during this period. All subjects were submitted to serological tests for the detection of the following markers of hepatitis B virus (HBV) infection: HBsAg, anti-HBc, HBeAg, anti-HBe, and anti-HBs, with no HBsAg, anti-HBc, HBeAg or anti-HBe being detected. A microparticle enzyme immunoassay (MEIA) revealed the presence of anti-HBs at protective titers (> or = 10 mIU/ml) in 42 dentists (82.4%), with the anti-HBs titer being higher than 100 mIU/ml in 36 of them (70.6%) (good responders), between 10 and 100 mIU/ml in 6 (11.8%) (poor responders), and lower than 10 mIU/ml in 9 (17.6%) (non-responders). According to clinical data and serological tests, none of the dentists had presented disease or latent HBV infection during the eight years following the first vaccination. A 2 micrograms booster dose was administered intradermally to eight dentists with anti-HBs titers lower than 10 mIU/ml (non-responders) and to six dentists with titers ranging from 10 to 100 mIU/ml (poor responders); the determination of anti-HBs one month later demonstrated the occurrence of seroconversion in the eight non-responders and an increase in anti-HBs titer in the six poor responders. In summary, the present results demonstrated the prolonged persistence of protection against HBV infection and the development of immunologic memory provided by vaccination against HB--with intradermal application of three 2 micrograms doses of the Belgian recombinant vaccine at 0, 1, and 6 months--carried out eight years before in 51 dentists.

Impact of a birth dose of hepatitis B vaccine on the reactogenicity and immunogenicity of diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type b combination vaccination

OBJECTIVES

To assess the impact of a birth dose of hepatitis B vaccine (HepB) on the reactogenicity and immunogenicity of a novel diphtheria-tetanus-acellular pertussis (DTaP)- HepB-inactivated poliovirus (IPV)/ type b (Hib) combination vaccine administered subsequently at 2, 4 and 6 months of age.

METHODS

Neonates ( = 550) were randomized into two groups with regard to receipt of HepB at birth. All subjects in both groups received DTaP-HepB-IPV/Hib at 2, 4 and 6 months of age. Solicited local and general adverse events were recorded for 8 days after each dose. Antibodies to hepatitis B surface antigen were measured 1 month after the third dose of DTaP-HepB-IPV/Hib in a subset of 170 infants; titers of at least 10 mIU/ml were considered protective.

RESULTS

The DTaP-HepB-IPV/Hib combination vaccine was well-tolerated in both groups. Of the infants who received a birth dose of HepB, 22.6% had severe (Grade 3) reactions after any of the three doses of DTaP-HepB-IPV/Hib combination vaccine compared with 23.2% of subjects who did not receive a birth dose of HepB (difference, -0.5%; 90% confidence interval, -7.4 to 6.1). Antibody to hepatitis B surface antigen titers were > or =10 mIU/ml for all tested infants. Geometric mean titers were 2996.2 and 1240.1 mIU/ml with and without a birth dose of HepB, respectively.

CONCLUSIONS

A HepB birth dose does not increase the reactogenicity of a combination DTaP-HepB-IPV/Hib vaccine administered at 2, 4 and 6 months of age, and all tested subjects achieved protective anti-HBs titers (> or =10 mIU/ml), although geometric mean titers were higher when a birth dose of HepB was given.

Persistence of antibody and immunologic memory in children immunized with hepatitis B vaccine at birth

Forty-two healthy children immunized with a course of hepatitis B vaccine beginning at birth were tested at 6 years of age for persistence of anti-hepatitis B antibody (anti-HBs) and then given a booster dose of vaccine. Although nearly one-half had become seronegative, all retained robust immunologic memory and rapidly regained a protective anti-HBs titer of at least 10 mIU/ml after booster vaccination.

Persistence of immunologic memory for 13 years in recipients of a recombinant hepatitis B vaccine

All subjects in this clinical study gave informed written consent, and guidelines of the authors' institution regarding human experimentation were observed in the conduct of the study. A booster dose of vaccine given to 18 adolescents (immunized as children) and 7 older adults immunized 13 years earlier with a 3-dose course of recombinant hepatitis B vaccine induced a strong secondary antibody response, demonstrating that the vaccinees retained immunologic memory for HbsAG. Within one week, booster vaccination induced an 11 to 24-fold rise in the GMT of anti-HBs which continued, reaching 52 to 319-fold after 4 weeks. Significantly even the 5 individuals with less than 10 mIU/ml of anti-HBs prior to the booster all had impressive responses to the booster dose.

Lifelong protection against hepatitis B: the role of vaccine immunogenicity in immune memory

Long-term protection against hepatitis B (HB) disease is dependent on persistence of a strong immune memory. This paper presents and discusses new knowledge that allows a better understanding of the mechanisms of long-term protection following hepatitis B vaccination. Studies have revealed links between specific lymphoproliferation, the in vivo humoral response and immune memory. The strength of immune memory and of a subsequent secondary immune response can therefore be predicted by the antibody response following primary vaccination. Vaccine antigen dose and structure have been identified as important influences in the primary antibody response and development of immune memory. The data and considerations presented support the use of highly immunogenic HB vaccines in order to provide long-lasting protection against HB disease.

DNA vaccines

The premise that DNA coding for antigens produces proteins to stimulate the immune system when inoculated directly into muscle tissues, has the immense attractions of simplicity, versatility and economy. When other vaccination approaches are experiencing practical problems, meeting such challenges as AIDS and malaria, considerable attention has focused on DNA vaccines with entire conferences and a flood of commercial companies devoted to exploring the possibilities. A number of clinical trials for both infectious diseases and cancer have already commenced, even though a number of major issues have to be resolved.

Do we need 3 doses of hepatitis B vaccine?

The hepatitis B virus (HBV) vaccine may provide protection through the clonal expansion of specific memory cells without necessarily having to produce high serum antibody levels. We develop a mathematical model which distinguishes between the accumulation of sensitive memory B and T-helper cells prior to a booster and the high circulating antibody levels present in an individual after a booster. We suggest this immune memory accumulates primarily in an antigen-independent fashion. These phenomena suggest individuals may be immune to infection six months after the priming vaccine dose(s) regardless of whether they receive a booster or not. This hypothesis is supported by immunogenicity data and by two independent vaccine efficacy trials comparing 0, 1 month schedules with 0, 1 and 6 month schedules.