WHO strategy for the global elimination of new cases of hepatitis B

Breastfeeding and chronic HBV infection: Clinical and social implications

Mother-to-child transmission of hepatitis B virus (HBV) is among the most important causes of chronic HBV infection and is the commonest mode of transmission worldwide. Currently, the presence of HBsAg, HBeAg and HBV DNA in breast milk is confirmed. Several studies have reported that breastfeeding carries no additional risk that might lead to vertical transmission. Beyond some limitations, the surveys have not demonstrated any differences in HBV transmission rate regarding feeding practices in early childhood. Promotion of breastfeeding is substantial, especially for low-income individuals and regions with uncertain, unfeasible, and unsafe water supplies. Lactoferrin, minimal inflammation or activation within the infant gut during exclusive breastfeeding, and nonspecific biological molecules in the milk are identified as major factors of breast-milk defense. This review discusses preemptive antiviral therapy during pregnancy and lactation. Long-term follow up of breast-milk HBV concentrations and correlation with serum viral load; nucleos(t)ide analogue concentrations in breast milk in HBV-positive mothers in the setting of chronic HBV infection; safety of antiviral therapy during pregnancy and lactation; and the difference in viral load in the milk in exclusive or non-exclusive breastfeeding are still open questions. The paper reviews the current data and outlines the course of further investigation into this often underestimated issue.

Pregnancy and chronic hepatitis B virus infection

The combination of chronic hepatitis B virus (HBV) infection and pregnancy presents unique management questions. Aspects of care that need to be considered include effects of hepatitis B on pregnancy, effects of pregnancy itself on the course of hepatitis B infection, treatment of hepatitis B during pregnancy and prevention of mother-to-infant transmission. Chronic HBV infection is usually mild in pregnant women, but may flare shortly after delivery. Effect of HBV infection on pregnancy outcomes are generally favorable, but may depend on severity of liver disease. Mother-to-infant transmission can be minimized by current immunoprophylaxis strategies, however, high levels of viremia in mothers may be a factor in the small but reproducible failure rate of current immunoprophylaxis strategies. Use of antivirals during pregnancy needs to be individualized. Careful planning and management of pregnancy must be done among patients with chronic HBV infection.

Lamivudine in late pregnancy to prevent perinatal transmission of hepatitis B virus infection: a multicentre, randomized, double-blind, placebo-controlled study

This randomized, double-blind, placebo-controlled study evaluated whether lamivudine given during late pregnancy can reduce hepatitis B virus (HBV) perinatal transmission in highly viraemic mothers. Mothers were randomized to either lamivudine 100 mg or placebo from week 32 of gestation to week 4 postpartum. At birth, infants received recombinant HBV vaccine with or without HBIg and were followed until week 52. One hundred and fifty mothers, with a gestational age of 26-30 weeks and serum HBV DNA >1000 MEq/mL (bDNA assay), were treated. A total of 141 infants received immunoprophylaxis at birth. In lamivudine-treated mothers, 56 infants received vaccine + HBIg (lamivudine + vaccine + HBIg) and 26 infants received vaccine (lamivudine + vaccine). In placebo-treated mothers, 59 infants received vaccine + HBIg (placebo + vaccine + HBIg). At week 52, in the primary analyses where missing data was counted as failures, infants in the lamivudine + vaccine + HBIg group had a significant decrease in incidence of HBsAg seropositivity (10/56, 18%vs 23/59, 39%; P = 0.014) and in detectable HBV DNA (11/56, 20%vs 27/59, 46%; P = 0.003) compared to infants in the placebo + vaccine + HBIg group. Sensitivity analyses to evaluate the impact of missing data at week 52 resulting from a high dropout rate (13% in the lamivudine + vaccine + HBIg group and 31% in the placebo + vaccine + HBIg group) remained consistent with the primary analysis in that lower transmission rates were still observed in the infants of lamivudine-treated mothers, but the differences were not statistically significant. No safety concerns were noted in the lamivudine-treated mothers or their infants. Results of this study suggest that lamivudine reduced HBV transmission from highly viraemic mothers to their infants who received passive/active immunization.

Elective caesarean section versus vaginal delivery for preventing mother to child transmission of hepatitis B virus--a systematic review

Background

Caesarean section before labor or before ruptured membranes ("elective caesarean section", or ECS) has been introduced as an intervention for preventing mother-to-child transmission (MTCT) of hepatitis B virus (HBV). Currently, no evidence that ECS versus vaginal delivery reduces the rate of MTCT of HBV has been generally provided. The aim of this review is to assess, from randomized control trails (RCTs), the efficacy and safety of ECS versus vaginal delivery in preventing mother-to-child HBV transmission.

Results

We searched Cochrane Pregnancy and Childbirth Group's Trials Register (January, 2008), the Cochrane Central Register of Controlled Trials (the Cochrane Library 2008, issue 1), PubMed (1950 to 2008), EMBASE (1974 to 2008), Chinese Biomedical Literature Database (CBM) (1975 to 2008), China National Knowledge Infrastructure (CNKI) (1979 to 2008), VIP database (1989 to 2008), as well as reference lists of relevant studies. Finally, four randomized trails involving 789 people were included. Based on meta-analysis, There was strong evidence that ECS versus vaginal delivery could effectively reduce the rate of MTCT of HBV (ECS: 10.5%; vaginal delivery: 28.0%). The difference between the two groups (ECS versus vaginal delivery) had statistical significance (RR 0.41, 95% CI 0.28 to 0.60, P < 0.000001). No data regarding maternal morbidity or infant morbidity according to mode of delivery were available.

Conclusion

ECS appears to be effective in preventing MTCT of HBV and no postpartum morbidity (PPM) was reported. However, the conclusions of this review must be considered with great caution due to high risk of bias in each included study (graded C).

Improving outcomes for patients with chronic hepatitis B

A focused meeting on hepatitis B virus (HBV) infection was held at the United States National Institutes of Health in Washington, DC, in April 2006. This meeting focused on new and historical data and served as a review for basic scientists and clinicians, as well as representatives from the pharmaceutical industry. Understanding HBV disease must include up-to-date information concerning virology, immunology, animal models, natural history, prevalence, and transmission risk, as well as an understanding of the evolving therapies for this life-threatening infection. Serious outcomes such as advanced fibrosis, cirrhosis, liver failure and hepatocellular carcinoma from hepatitis B infection appear to be closely tied to both historical and current serum levels of HBV DNA, and elevated serum levels of liver enzymes. Decreasing risk events and vaccinating susceptible individuals are key steps in managing this global scourge. New oral treatments for patients withchronic hepatitis B infection characterized by more potent antiviral effects, less toxicity, and minimal or no risk of resistance were reviewed and emphasized. Entecavir and pegylated interferons have recently been approved for treatment of chronic hepatitis B. Further expansion of our information about lamivudine and adefovir were highlighted. Several other new anti-HBV agents are also in phase II or III clinical trials or have been submitted for licensing including LdT (telbivudine). The NIH review meeting is summarized in this review and new and emerging areas of information are highlighted.

Evaluation of immunogenicity and reactogenicity of recombinant DNA hepatitis B vaccine produced in India

AIM

(1) To gain information on immune responses to an accelerated schedule of 0, 1, and 2 mo in paramedical staff and BDS students who are at an increased risk of getting hepatitis B infection and come under high risk groups. (2) To assess the efficacy and safety of Enivac-HB in different age groups, using genetically modified yeast strain Pichia pastoris, a new recombinant hepatitis B vaccine developed and manufactured in India.

METHODS

A prospective, comparative, and single blinded trial of rapid (0, 1, and 2 mo) hepatitis B immunization schedule was reported. A total of three hundred and seven (212 females and 95 males) healthy volunteers divided into three age groups (18-29, 30-39, and 40-49) were enrolled after screening for markers of hepatitis B. All the volunteers received 20 mg of the vaccine intramuscularly at 0, 1, and 2 mo.

RESULTS

Geometric mean titers were calculated pre and post vaccination. Before immunization the GMT was 0.0124 mIU/mL. One month after the administration of the third dose of recombinant vaccine 296/307 (96.5%) subjects achieved seroprotective levels of anti-HBs. The geometric mean anti-HBs titers achieved after one month of the third dose was 2 560.0 mIU/mL. The geometric mean anti-HBs titer of males was 2 029.0 mIU/mL, while that of the females was 2 759.0 mIU/mL. In the age group of 18-29 years, anti-HBs titer was 3 025.0 mIU/mL, while that in the age group of 30-39 years was 2 096.0 mIU/mL. In third age group of 40-49 years, anti-HBs titer was 1 592.0 mIU/mL. Hyper-responses (anti-HBs> or =100 mIU/mL) were shown in 88.0% (271/307) of subjects. Eleven (3.5%) subjects responded poorly to the vaccine in the age group of 40-49 years. There was only mild pain at the site of injection otherwise there were no other adverse drug reactions (ADRs).

CONCLUSION

This vaccine (Enivac-HB) is safe and efficacious, providing significant protection after the third dose and rapid hepatitis B immunization schedule of 0, 1, and 2 mo can be recommended whenever rapid protection is the goal.

Deficiency in virion secretion and decreased stability of the hepatitis B virus immune escape mutant G145R

Hepatitis B virus with a G145R mutation in the small surface protein is considered the quintessential immune escape mutant because it frequently is found in vaccinated individuals with breakthrough infections and liver transplant recipients under anti-hepatitis B surface antigen (HBsAg) immunoglobulin prophylaxis. Nowadays the prevalence of the variant progressively increases. However, because spread of a virus depends not only on immune pressure but also on the viral phenotype, we investigated the biologic properties of the G145R variant. The G145R mutation was introduced into wild-type (Wt) virus genome by in vitro mutagenesis. After transfection into human hepatoma cells, the DNA, RNA, and protein synthesis and viral secretion ability of the mutant were studied. Furthermore, cotransfection studies were performed with the G145R variant and a Wt virus S-protein expressing construct and vice versa. Production and stability of viral messenger RNAs (mRNAs), DNA, and proteins were not affected by the G145R mutation. In contrast, secretion of mutant virions was reduced significantly. Only 20% of virions were found in the medium of G145R variant-transfected cells compared with Wt virus. Furthermore, mutant virions were more sensitive to detergent treatment suggesting a diminished stability. In cotransfection studies, Wt virus S-protein rescued secretion of mutant virions, whereas mutant S-protein had a transdominant negative effect on secretion of Wt virus. Both mechanisms may support persistence of the defective mutant in a mixed population with Wt virus. In conclusion, the significant defect of the G145R mutant for secretion of infectious virions and the diminished stability of mutant virions may limit global spread of the mutant.

Selection of a secretion-incompetent mutant in the serum of a patient with severe hepatitis B

BACKGROUND AND AIMS

A secretion-incompetent, highly replicating hepatitis B variant was previously found as the dominant viral population in the serum of a liver transplant recipient with severe hepatitis B reinfection. The secretion block resulted from mutations in the S protein, including the Gly145Arg substitution known to emerge under antibody to hepatitis B surface antigen immunoglobulin treatment. Here we investigated the mechanisms that allow selection of a secretion-incompetent virus as the predominant strain in the serum.

METHODS

To reproduce the interaction of viral quasispecies occurring in vivo, cotransfection experiments were performed with full-length genomes containing wild-type or mutant sequences. In addition, the relevance of mutations in the common S part of the surface proteins for the competence of L and S protein to support viral secretion was studied.

RESULTS

A small amount of wild-type virus or of a wild-type S protein-expressing variant rescued secretion of the defective mutant. In the secreted virions, the high-replicating mutant genome was predominant. Selection of the defective mutant was further supported by a transdominant negative effect of mutant S protein on wild-type virion secretion. In contrast, mutant L protein with the same c-terminal mutations as mutant S protein efficiently supported virion formation and secretion.

CONCLUSIONS

Interaction of the variant with a small amount of wild-type virus can reverse its secretion-defective phenotype. Mutations in the common region of S and L protein have different consequences for the ability of the envelope proteins to support virion assembly and secretion.

Compliance with hepatitis B vaccination in 1175 heroin users and risk factors associated with lack of vaccine response

AIMS

To investigate the feasibility of hepatitis B vaccination among heroin users, assessing adherence to the vaccination schedules and identifying factors associated with antibody response.

DESIGN AND PARTICIPANTS

A large cohort study in nine public centres for drug users (PCDUs) in north-eastern Italy, with data collected between January 1989 and December 1998. A total of 1175 heroin users were selected and vaccinated with a recombinant vaccine using two schedules (0-1-6 months and 0-1-2 months).

FINDINGS

Eighty-eight per cent of patients completed the vaccination series and a protective antibody response occurred in 77% of subjects. Completion of the vaccination series was not related to the length of the vaccination schedule or whether the patient was still in drug abuse treatment at the end of the series, but was related strongly to the number of patients enrolled at each PCDU (Spearman correlation = - 0.93, P < 0.001). Four variables were significantly associated with lack of seroconversion in response to vaccination: older age (AOR = 0.91 per year, 95% CI 0.88-0.94, P < 0.001), 2-month vaccination schedule (AOR = 3.10, 95% CI 2.06-4.68, P < 0.001), HCV seropositivity (AOR = 0.69, 95% CI 0.47-0.99, P = 0.04), HIV seropositivity (AOR = 0.27, 95% CI 0.10-0.77, P = 0.01).

CONCLUSIONS

A large-scale, multi-site hepatitis B vaccination programme for heroin users proved feasible and effective. The factors associated with a lack of antibody response may be useful in identifying patients who would benefit most from routine post-vaccination testing, with booster doses for non-responders. These results suggest that hepatitis B vaccination for drug users should become a routine public health practice.

Rapid seroprotection against hepatitis B following the first dose of a Pre-S1/Pre-S2/S vaccine

BACKGROUND/AIMS

Will immunization with an experimental Pre-S1/Pre-S2/S hepatitis B vaccine (Bio-Hep-B) induce faster seroprotection using fewer doses as compared with a yeast derived S vaccine (Engerix B).

METHODS

Healthy volunteers, n = 36, mean age 23 y, randomized to receive 2 or 3 doses of both vaccines given months 0 and 6, or 0, 1 and 6.

RESULTS

Following primary immunization, seroprotection occurred in 6, 39, 53 and 60% in the Bio-Hep-B group at weeks 1, 2, 3 and 4, compared with 0, 12, 18 and 12.5% in the Engerix-B vaccinees, respectively. Six months following injection of the first dose, seroprotection was 70 and 25% in Pre-S/S and S vaccinees respectively. Area under the curve in vaccinees of Bio-Hep-B; versus Engerix-B showed mean anti-HBs level of 365 +/- 166 and 85 +/- 48 mIU/ml x day respectively (P = 0.012). At month 7, 100% seroprotection was achieved in both groups while anti-HBs rose from 81 to 28,800 mIU/ml and from 12 to 923 mIU/ml in recipients of Bio-Hep-B and Engerix-B respectively (P < 0.025).

CONCLUSIONS

Bio-Hep-B induces rapid seroprotection against hepatitis B in 60-70% of vaccinees, within 4-24 weeks after the first dose. Two instead of the conventional three doses of the Pre-S/S vaccine may be sufficient to induce adequate seroprotection.

Predictors of positivity for hepatitis B and the derivation of a selective screening rule in a Canadian sexually transmitted disease clinic

OBJECTIVES

To determine the prevalence of hepatitis B surface antibody (anti-HBs) and antigenemia (HBsAg), the risk factors for seropositivity and the effectiveness of a selective serologic screening rule among sexually transmitted diseases (STD) clinic attendees.

STUDY DESIGN

Clients in the Hamilton STD Clinic were surveyed from October 1992 to July 1993 on sociodemographic, past medical, and behavioural data, were tested for several STDs and were offered serological testing and vaccination against hepatitis B. Predictors of seropositivity were determined by single variable analysis. A selective serologic screening rule was derived using logistic regression modelling.

RESULTS

The seroprevalence of anti-HBs was 6.8% (21/310) in the 310 of 385 clients (80.5%) who agreed to be tested and interviewed. There were no HBsAg carriers. Five independent risk factors were identified by logistic regression: (1) age greater than 35 years; (2) birth outside Canada and histories of; (3) syphilis; (4) gonorrhoea; or (5) injection drug use. If clients with at least one of these predictors had been tested, 34.5% would have been selected for serologic testing and 85.7% of all positives would have been detected. The screening rule was more effective for men than for women.

CONCLUSION

In this low prevalence setting, selecting STD clinic clients based on the presence of any one of five risk predictors appears to be an effective strategy for hepatitis B serologic screening in the context of a Canadian vaccination program.

Molecular analysis of the a determinant of HBsAg in children of HBeAg-positive mothers upon failure of postexposure prophylaxis

OBJECTIVE

To investigate the a determinant of hepatitis B virus (HBV) S gene for the presence of mutations responsible for vaccine failure.

METHODS

The a determinant of HBV S gene was amplified in sera obtained from 11 HBV-positive infants and children born to asymptomatic HBeAg-positive mothers by nested polymerase chain reaction (PCR) and subsequently subjected to direct sequencing. The sequences obtained were translated into the corresponding amino acids and compared to amino acid sequences of HBV subtype adr. All infants under investigation had received recombinant hepatitis B vaccine within 24 hours after delivery and had completed the recommended vaccination course, consisting of three to four doses administered at defined intervals.

RESULTS

The usual divergence regarding genotype and subtype was identified among the 11 samples tested. Only two exhibited a point mutation within the a determinant, one of which consisted of a substitution of glycine with alanine at position 145, and the other of a substitution of glutamine with arginine at position 129.

CONCLUSION

Eleven neonates were positive for HBV infection, and two of them showed point mutations that might have rendered the virus resistant to the vaccine, possibly due to a change in the S protein's secondary structure. Yet, this remains a matter of speculation, since the other seven cases positive for hepatitis B viral DNA merely demonstrated the usual genotype and subtype. The presence of escape mutants of HBV can be considered rather negligible with respect to vaccination programs, especially as the vaccine has been shown to reduce hepatitis B, as well as hepatocellular carcinoma efficiently.

Targeted hepatitis B vaccination--a cost effective immunisation strategy for the UK?

OBJECTIVE

To compare the potential cost effectiveness of vaccination against hepatitis B virus (HBV) targeted at genitourinary clinic (GU) attendees with that of universal infant vaccination.

DESIGN

A mathematical model of sexual and perinatal transmission of HBV was used to compare the effectiveness among heterosexual and homosexual populations of programmes of mass infant vaccination and targeted immunisation of genitourinary medicine (GU) clinic attendees. Each was applied to 90% of the eligible population with differing assumptions about rates of compliance and seroconversion - problems of delivery (obtaining high compliance) was considered a significant drawback of targeted vaccination. Observed relationships between GU clinic attendance and sex partner change rates for heterosexuals and for homosexuals were used to define the rates of vaccination uptake within sexual activity risk groups.

SETTING

England and Wales.

RESULTS

Model results showed that for heterosexuals universal infant vaccination became more effective than clinic based vaccination only approximately 40 years after the start of the programme and that the predicted cost effectiveness of GU clinic vaccination was greater at all times. For homosexuals, clinic vaccination was always more effective over the time frame considered, but by 50 years if it were carried out without prior screening it had become appreciably less cost effective than a mass infant programme. With prior screening in GU clinics this cost effectiveness deficit was only marginal.

CONCLUSIONS

Targeted vaccination might have a much greater potential than is realised at present, particularly if it were possible to improve compliance of clinic attendees. A fuller comparison between mass infant and targeted vaccination must await the specific inclusion in the model of other risk groups such as intravenous drug users. An important determinant of the relative merits of the two approaches is the relationship between rates of attendance and of changing sexual partners. Further research on this is required.

Epidemiological patterns of hepatitis B virus (HBV) in highly endemic areas

This paper uses meta-analysis of published data and a deterministic mathematical model of hepatitis B virus (HBV) transmission to describe the patterns of HBV infection in high endemicity areas. We describe the association between the prevalence of carriers and a simple measure of the rate of infection, the age at which half the population have been infected (A50), and assess the contribution of horizontal and perinatal transmission to this association. We found that the two main hyper-endemic areas of sub-Saharan Africa and east Asia have similar prevalences of carriers and values of A50, and that there is a negative nonlinear relationship between A50 and the prevalence of carriers in high endemicity areas (Spearman's Rank, P = 0.0086). We quantified the risk of perinatal transmission and the age-dependent of infection to allow a comparison between the main hyper-endemic areas. East Asia was found to have higher prevalences of HBeAg positive mothers and a greater risk of perinatal transmission from HBeAg positive mothers than sub-Saharan Africa, though the differences were not statistically significant. However, the two areas have similar magnitudes and age-dependent rates of horizontal transmission. Results of a simple compartmental model suggest that similar rates of horizontal transmission are sufficient to generate the similar patterns between A50 and the prevalences of carriers. Interrupting horizontal transmission by mass immunization is expected to have a significant, nonlinear impact on the rate of acquisition of new carriers.

The transmission dynamics of hepatitis B in the UK: a mathematical model for evaluating costs and effectiveness of immunization programmes

Complex hepatitis B (HBV) epidemiology makes it difficult to evaluate and compare effectiveness of different immunization policies. A method for doing so is presented using a mathematical model of HBV transmission dynamics which can represent universal infant and adolescent vaccination strategies and those targeted at genito-urinary (GU) clinic attenders and infants born to infectious mothers. Model structure, epidemiological underpinning, and parameterization, are described. Data from the UK National Survey of Sexual Attitudes and Lifestyles is used to define patterns of sexual activity and GU clinic attendance; data deficiencies are discussed, in particular that of UK seroprevalence of HBV markers stratified by age, sex, and risk factors. General model predictions of endemic HBV marker prevalence in homosexual and heterosexual populations seem consistent with published UK data. The simulations exhibit non-linearities in the impact of different vaccination strategies. Estimated number of carriers prevented per vaccine dose for each strategy provides a measure of costs and benefits, varying temporally over the course of a programme, and with level of vaccine coverage. Screening before vaccination markedly increases payback per dose in homosexuals but not in heterosexuals; mass infant vaccination gives the poorest effectiveness ratio and vaccination of infants after antenatal screening the best; in general, increasing vaccine coverage yields lower pay-back per dose. The model provides a useful framework for evaluating costs and benefits of immunization programmes, but for precise quantitative comparison more UK epidemiological data is urgently needed.

Epidemiology of childhood hepatitis B in India: vaccination related issues

It has been estimated that presently hepatitis B kills more people every day than AIDS kills in a year world-wide. Infection with hepatitis B produces a wide range of manifestations ranging from asymptomatic carriers to persistent infections leading to chronic liver diseases and hepatocellular carcinoma. Availability of effective and safe vaccine has made all this preventable. To formulate on appropriate vaccination strategy for India the epidemiology of hepatitis B needs to be defined. This report critically reviews the available data. The burden of long term sequelae of HBV infection is probably under-diagnosed and under-reported in India. Prevalence studies of HBV markers indicate that India falls under the area of intermediate endemicity. Limited data on age-specific prevalence of HBV markers suggests that the majority of the infection seems to take place below 15 years of age, and most of it under one year. Perinatal transmission appears to contribute significantly to the carrier pool. Childhood vaccination for HB among the general population is the obvious strategy of choice. But more information is required to decide on the timing of the first dose.

Simultaneous administration of hepatitis B vaccine with other E.P.I. vaccines

Development of recombinant DNA vaccine against hepatitis B grown on cultured yeast cell has made it possible to mount a world-wide effort to control and eradicate Hepatitis B infection. However, the currently recommended schedules (0, 1 & 2 months, and 0-1 and 6 months) do not coincide with the scheduled visits for other E.P.I. vaccines, and necessitate additional visits for Hepatitis B vaccination. This study was therefore carried out to find out if adequate seroconversion occurs to Hepatitis B vaccine when given with other EPI vaccines or not? Thirty nine infants born to Australia antigen positive mothers from among 850 screened pregnant mothers were recruited to receive Hepatitis B vaccine (Engerix B-10 micro gram each) at 0, 6 and 14 wks (group A) or at 0, 1 and 2 months (group B). Thirty-one infants were recruited in group A and 8 in group B. The cord blood was collected and the first dose of vaccine was given within 48 hours of birth. Simultaneous B.C.G. was given at the left deltoid. Other E.P.I. vaccines were given qt 6, 10 and 14 wks in group A and at 2, 3 and 4 months in group B. Repeat blood samples were collected prior to giving each dose of Hepatitis B vaccine, and 4 weeks after the last dose. All blood samples were assayed for HBsAg and HBsAb at the National Institute Of Communicable Diseases, utilizing standard ELISA kits. The seroconversion rates following one, two and three doses of Hepatitis B vaccine were 3.33%, 55.5%, 96.15% and 0%, 62.5% and 100% in group A and B respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunogenicity of 20 micrograms of recombinant DNA hepatitis B vaccine in healthy neonates: a comparison of three different vaccination schemes

The immunogenicity of a full dose (20 micrograms) of recombinant DNA yeast-derived hepatitis B vaccine (Engerix-B) was assessed in healthy neonates in order to compare three candidate vaccination schemes. After randomization 162 newborns of hepatitis B surface antigen (HBsAg) negative mothers entered the study. Neonates received hepatitis B vaccine according to a four-dose vaccination scheme starting either at month 3 (scheme I: months 3, 4, 5, and 11) or at birth (scheme III: months 0, 1, 2, and 11). Another group of neonates received hepatitis B vaccine according to a three-dose scheme starting at birth (scheme II: months 0, 1, and 6). Serious adverse reactions were not observed; 2.5% of the vaccinated newborns suffered mild transient local symptoms. The vaccine was highly immunogenic irrespective of vaccination scheme; all infants developed anti-HBs levels > or = 10 IU/L, 97% > or = 100 IU/L. The immunogenicity of hepatitis B vaccine after primary and booster vaccinations, administered in the four-dose scheme started at birth, was significantly higher (P < 0.05) than in the three-dose scheme started at birth. Hepatitis B vaccination according to the four-dose scheme started at month 3 produced significantly higher (P < 0.05) antibody levels in comparison to the four-dose scheme started directly after birth. This study showed that a four-dose hepatitis B vaccination scheme starting at month 3 resulted in the highest antibody levels of the three schemes investigated and can be recommended for incorporation in the Expanded Programme on Immunization in The Netherlands.

A double sandwich monoclonal enzyme immunoassay for detection of hepatitis B surface antigen

An enzyme immunoassay for detection of hepatitis B surface antigen based on the use of 3 monoclonal antibodies (mAbs) was developed: an IgM as capture and 2 IgG1 for detection. The system biotin-streptavidin was compared with direct conjugation of mAbs to peroxidase and was preferred because of its higher signal to noise ratio. The possibility of simultaneous addition of human serum and biotin-mAb was discarded because of an evident prozone effect with some sera containing high HBsAg levels. The conjugation of biotin to IgG1 mAbs through a spacer arm (amidocaproyl) and the use of a highly sensitive substrate (tetramethylbenzIdine) improved the assay detection limit by about 10 times.

Control of hepatitis B through routine immunization of infants: the need for flexible schedules and new combination vaccine formulations

Universal immunization of infants is essential to the control of hepatitis B in areas of high endemicity where infection commonly occurs in infants and children. It is also an attractive strategy for ultimately reducing hepatitis-B-associated acute and chronic liver disease in areas of lower endemicity where infections occur primarily in adolescents and adults. Integration of hepatitis B vaccine with other routine paediatric immunizations, using flexible scheduling, will enhance compliance while minimizing the need for additional resources. Clinical studies demonstrate that a very high proportion of healthy infants and adults develop a protective level of antibody when given hepatitis B vaccine using a wide range of schedules. Compliance with universal vaccination of infants against hepatitis B may be enhanced by the development of new combination vaccines (e.g. diphtheria-tetanus-pertussis-Haemophilus influenzae b-hepatitis B) that allow complete immunization against several antigens with a minimal number of injections.

A hepatitis B vaccination programme for inner metropolitan Sydney neonates

OBJECTIVE; To review the effectiveness of a hepatitis B vaccination programme for high risk infants within a mobile urban population.

DESIGN

A follow-up study of 1429 infants enrolled consecutively in the programme from September 1987 to December 1988.

SETTING

The programme was established in early childhood centres within inner metropolitan Sydney, an area where 30% of residents were born in non-English speaking countries and where doubts had previously been expressed about the efficacy of vaccination.

PARTICIPANTS

Neonates born to mothers who were surface antigen positive, born in selected countries with a 5% prevalence of surface antigen carriage, Aboriginal or intravenous drug users.

OUTCOME MEASURES

Documented vaccination given by early childhood centre nurses. Some adjustment was made for parents' reports of vaccination given elsewhere.

RESULTS

Two vaccinations were given to 87% and three to 73% of these infants. If we include vaccinations apparently given elsewhere we estimate that 92% may have been fully protected.

CONCLUSION

The programme produced high rates of compliance with vaccinations within a population where the delivery of such a service was thought to be difficult. Experience with the current State policy for hepatitis B vaccination indicates that it may not optimally reduce the pool of surface antigen carriers within our community.

Vaccine preventable viral diseases in developing countries

There are several viral infectious diseases with a high impact on developing countries which can be prevented by immunization with existing vaccines. The most important are poliomyelitis, measles, hepatitis B and yellow fever. Vaccines against poliomyelitis and measles used within the framework of the WHO/Expanded Programme on Immunization prevent about 1.4 million deaths from measles and 360,000 cases of paralytic polio per year in developing countries, but about 1.5 million measles' deaths and 200,000 cases of paralytic polio still occur. Hepatitis B infection and its sequelae are responsible for over 50 million infections and one million deaths annually. Highly effective hepatitis B vaccines are now available and the price of these vaccines for the developing world has fallen dramatically. Despite the availability of a safe and efficacious yellow fever vaccine since 1937, 5400 cases of this disease with 3200 deaths were reported in Africa and South America from 1986 to 1988. Because of the efficacy of existing vaccines and the lack of animal reservoirs or vectors, systematic vaccination programmes within the framework of the Expanded Programme on Immunization (EPI) could theoretically eliminate and even eradicate poliomyelltis, measles and hepatitis B. Many different obstacles need to be overcome before these goals are realized.