Comparative immunogenicity under field conditions of two recombinant hepatitis B vaccines in 8-10-year-old children

24 year outcomes of hepatitis B vaccination in Hangzhou, China

To evaluate the impact of the universal infant HepB vaccination program on hepatitis B virus infection in Hangzhou, China. Hepatitis B incidences and HepB vaccination rates of Hangzhou from 1990 to 2003 were acquired from the historical paper-documents, while which were derived from China Information System for Diseases Control and Prevention and Zhejiang Information System for Immunization Program respectively from 2004 to 2013. A serology survey among person aged 0-59 y was conducted in Hangzhou in 2006. Participants were selected by stratified, multi-stage random sampling. Serum specimens were tested for HBsAg, anti-HBs , anti-HBc , HBeAg and anti-HBe by ELISA. For the past 24 years, hepatitis B incidence and mortality of Hangzhou declined dramatically (χ(2) = 3.2 × 10(4); χ(2) = 172.443; both P for trend < 0.001). Both urban and rural incidence descended (χ(2)urban = 1.904 × 10(4); χ(2)rural = 1.633 × 10(4) ; both P for trend < 0.001).Hepatitis B patients mainly concentrated in 20-40 y old; workers and farmers were the main infection occupations, which was varies in different years (χ(2) = 1.619 × 10(3), P < 0.001). Significant association was found between incidence of hepatitis B and HepB vaccination rate (r = 0 .946, χ(2) = 11.813, Pfor trend = 0.001). A total of 5605 participants aged 0-59 y included in this serological survey. The prevalence of HBsAg, anti-HBs, anti-HBc, HBeAg and anti-HBe were 6.19%, 45.83%, 57.25%, 0.62%, and 4.37%, respectively. Hangzhou has successfully integrated the HepB into routine immunization programs and this has had a significant impact on decreasing the incidence of hepatitis B infection.

Long-term persistence of immunity after vaccination of pre-adolescents with low doses of a recombinant hepatitis B vaccine

BACKGROUND AND AIMS

Recent studies have shown no detectable antibodies and no response to a challenge dose of vaccine 10-20 y after receiving low doses (2.5-5 µg) of recombinant hepatitis B vaccine during first months of life. Little information is available on long-term persistence of immunity after vaccinating pre-adolescents with low doses of hepatitis B vaccine.

RESULTS

The results of 560 subjects were included in this analysis. All subjects had a seroprotective antibody titer (≥10 IU/L) one month post-primary vaccination; 5, 10 and 15 y post-vaccination 95%, 95% and 87% had detectable antibodies, and 82%, 86%, and 68% had a seroprotective antibody titer; GMTs were 73 IU/L, 89 IU/L, and 28 IU/L, respectively. More than 99.4% of subjects had an anamnestic response to a challenge dose of vaccine given 5, 10, or 15 y post-vaccination. Five and ten years post-booster dose 97% and 95% of subjects still have a seroprotective anti-HBs titer with GMTs 16-18-fold higher when compared with those observed 5-10 y post-primary vaccination.

MATERIALS AND METHODS

This randomized trial was initiated in 1996 with the main objective to assess the persistence of antibodies and immune memory 5, 10 and 15 y after vaccinating 8-10 y-old children with three doses of Recombivax 2.5 µg, as well as the short and long-term effect of a booster dose given at different intervals.

CONCLUSIONS

Virtually all children vaccinated at the age of 8-10 y with low doses of hepatitis B vaccine still have an excellent immune memory up to age of 25 y. The results of this study do not support the use of booster doses.

Antibody persistence and the effect of a booster dose given 5, 10 or 15 years after vaccinating preadolescents with a recombinant hepatitis B vaccine

The persistence of antibody obtained post-vaccination of preadolescents with three doses of Engerix-B and the effect of a booster administered 5, 10 or 15 years later were monitored in 663 vaccinees. Five, 10 and 15 years post-vaccination >94% of subjects had detectable antibodies and 88.2%, 86.4% and 76.7% had a titre ≥10 IU/L; GMTs were 269 IU/L, 169 IU/L and 51 IU/L, respectively; 99.1-100% vaccinees reached a titre ≥10 IU/l post-booster. GMTs were 118012 IU/L, 32477 IU/L, and 13946 IU/L when the booster was administered 5, 10 or 15 years post-vaccination, respectively. We conclude that vaccination induces immunity in the great majority of vaccinees for at least 15 years. The response to a booster dose suggests persistence of immune memory in almost all vaccinees. Although a booster dose increases substantially anti-HBs titres, the clinical relevance of such an increase remains unknown. These results do not support the need of a booster for at least 15 years when vaccinating preadolescents with Engerix-B.

Comparison of long-term immunogenicity (23 years) of 10 μg and 20 μg doses of hepatitis B vaccine in healthy children

To compare the long-term immunogenicity and seroprotection rates in healthy children following 23 years of vaccination with 10 μg or 20 μg doses of plasma-derived hepatitis B vaccine, we revisited all participants from our previous randomized controlled trial. At year 23, 81 participants were tested for HBV serological markers and HBV-DNA, and a booster dose was given to those with anti-HBs titer < 10 mIU/mL. After eliminating the interference of a Year 11 booster dose and vaccines received outside of the trial, around 50% of participants still maintained anti-HBs titers ≥ 10 mIU/mL in both 10 μg and 20 μg groups (p > 0.05). The peak immune response of vaccination (anti-HBs antibody levels at 12 mo after 1st vaccine dose) and Year 11 anti-HBs levels were significantly associated with Year 23 seroprotection rates. Most of the participants in both groups, regardless of their prior immune status, developed a rapid and robust anamnestic antibody response after the booster dose at year 23. No case of clinically significant HBV infection was observed during the entire study period of 23 y with only one transient HBsAg seroconversion in 10 μg vaccine group. We concluded that seroprotection provided by 10μg or 20 μg doses of hepatitis B vaccine persists for 23 years in more than half of vaccinated individuals in highly HBV-endemic areas, irrespective of 10 μg or 20 μg vaccine doses. Future studies with larger sample sizes comparing long-term efficacy of various doses of plasma-derived and recombinant HBV vaccines are recommended.

Antibody kinetics among 8-10 years old respondents to hepatitis B vaccination in a low endemic country and the effect of a booster dose given 5 or 10 years later

Few data are available concerning the persistence of anti-HBs and the effect of booster doses given several years post-vaccination against hepatitis B during preadolescence. The objective of this open-labelled clinical trial was to evaluate the persistence of antibodies after vaccination with three paediatric doses of Engerix-B at the age of 8-10 years and the effect of a booster dose given 5 (Group Y5) or 10 (Group Y10) years later. Anti-HBs were measured before and one month post-primary vaccination, then 5 and 10 years later, before the booster dose, as well as one month and 1 year post-booster. The anamnestic response was defined as a >or=fourfold increase of anti-HBs post-booster (>or=10 IU/L) when compared to pre-booster. Ten years post-primary vaccination, 559 of the 652 initially randomized subjects (86%) were eligible for analysis. Group Y5, 5 years post-booster results: 99% of subjects had detectable levels of antibodies and 96% a titer >or=10 IU/L. The anti-HBs GMTs decreased from 114,489 IU/L one month post-booster to 3354 IU/L 5 years later. Group Y10 results: 10 years post-primary vaccination 96% of subjects had a detectable level of anti-HBs and 85% were above the threshold of 10 IU/L. The GMTs one month post-booster were 31,030 IU/L. The challenge with a booster demonstrated an anamnestic response in 99% of subjects in group Y5 and 100% of subjects in group Y10. All subjects were anti-HBc negative. The booster doses were well tolerated. The excellent anamnestic response observed after the booster dose demonstrates the persistence of immunity in virtually all young adults vaccinated at the age of 8-10 with three paediatric doses of Engerix-B.

Comparative efficacy of two dosages of recombinant hepatitis B vaccine in healthy adolescents in India

BACKGROUND

Inclusion of hepatitis B vaccine in the Universal Programme of Immunization of all Asian and African countries is hampered by the economic burden on the health budget because of the cost of hepatitis B vaccines. Here we evaluated the immunogenicity, safety, efficacy, and the persistence of antibody to hepatitis B surface antigen (anti-HBs) titers of a new and a low cost recombinant hepatitis B vaccine GeneVac B, with 2 different dosages in healthy adolescents in India.

METHODS

GeneVac-B, a recombinant hepatitis B vaccine (Serum Institute of India, Pune, India), was administered in 10 or 20 microg dose intramuscularly to 2 groups of 100 healthy school-going adolescents at 0-, 1-, and 6-month intervals, who were followed up for 1 year. Group I received 20 mug doses whereas Group II received 10 mug doses. Blood samples were collected 1 month after each dose and 1 year after the third dose. The anti-HBs titers were assayed using commercially available kits to assess the immunogenicity of the 2 dosage schedules. Safety studies were also carried out.

RESULTS

The geometric mean titer value of the anti-HBs titer 1 month after the third dose was 2629 (mlU/mL) in Group I and 1373 mlU/mL for Group II subjects. One year after the third dose, the persistence of anti-HBs in those who had received 20 mug was 2262 mlU/mL whereas it was 1039 mlU/mL in the group receiving 10 microg doses. All the subjects in both the groups were seroprotected at 1 year after vaccination. None of the vaccinees exhibited serious adverse reactions throughout the study period.

CONCLUSIONS

The study demonstrated the immunogenicity of the recombinant hepatitis B vaccine, and confirms that the 0.5 mL (10 microg) dose of GeneVac B can be administered with satisfactory safety and immunogenicity to adolescents up to 19 years of age, reducing the cost to less than U.S. $1.00 per dose making it acceptable for the Universal Programme of Immunization of developing and under developed countries.

Impact of the quebec school-based hepatitis B immunization program and potential benefit of the addition of an infant immunization program

Ten years after a school-based hepatitis B immunization program was implemented, we conducted a study to assess the impact of the program, vaccine failures, risk factors and the number of cases potentially preventable by the addition of an infant vaccination program. The preteen vaccination program is highly effective. An infant immunization program would bring additional benefits.

Immunogenicity of two paediatric doses of monovalent hepatitis B or combined hepatitis A and B vaccine in 8–10-year-old children

Hepatitis A and B vaccines are highly immunogenic in three-dose schedules. To obtain an equivalent result in children with two paediatric doses would be of significant benefit. The purpose of this study was to measure the immunogenicity of a two-dose schedule in children with two licensed recombinant HBsAg containing vaccines given at paediatric doses, one of them combined with hepatitis A. Seven-hundred and four healthy school children aged 8-10 years were recruited in an open label study to receive either Twinrix Pediatric (360 El.U HAV antigen; 10 microg HBsAg) or Recombivax (2.5 microg HBsAg) vaccine intramuscularly 6 months apart. The seroconversion (>/=1 mIU/ml for anti-HBs antibodies and >/=33 mIU/ml for anti-HAV antibodies), seroprotection (anti-HBs >/=10 mIU/ml) rates and the geometric mean titers (GMTs) were determined 4-8 weeks after the second dose. The anti-HBs seroconversion rate was 97.1% with Twinrix and 97.2% with Recombivax. The seroprotection rates were 96.5 and 94.4%, respectively (P = 0.17). The GMT was higher with Twinrix than with Recombivax (3248 mIU/ml versus 742 mIU/ml, P < 0.0001). All the children vaccinated with Twinrix seroconverted to HAV and the GMT was 5168 mIU/ml. The obtained results suggest that two paediatric doses of hepatitis vaccines are highly immunogenic in 8-10-year-old children. This schedule could facilitate a greater vaccine acceptance and the addition of hepatitis A vaccine to existing adolescent universal hepatitis B virus immunization programs.

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).

Comparative long term immunogenicity of two recombinant hepatitis B vaccines and the effect of a booster dose given after five years in a low endemicity country

BACKGROUND

Few data are available concerning the long term immunogenicity of the pediatric doses of hepatitis B vaccines given to preteenagers. The long term effect of the booster dose in teenagers is unknown. We evaluated the immunogenicity of 2 pediatric hepatitis vaccines after primary vaccination and after a booster dose.

METHODS

A prospective 15-year follow-up study of the immunogenicity of 2 hepatitis B vaccines was initiated in 1995 in Quebec City, Canada. One year apart, 1129 children 8-10 years old received Engerix-B 10 microg (EB), and 1126 received Recombivax-HB 2.5 microg (RB) vaccine after a 0-, 1-, 6-month schedule. After 5 years, one-third of the 2 cohorts were randomly selected. A booster dose of EB 10 microg or RB 5 microg was administered according to the vaccine used in the primary immunization. Antibodies were measured before, 1 month after and 1 year after the booster injection.

RESULTS

Before the booster dose, anti-HB surface antibody (HBs) was detected in 94.7% of the EB subjects and in 95.2% of the RB subjects (P = 0.85). The geometric mean titer (GMT) was higher in the EB than in the RB group (252 mIU/mL versus 66 mIU/mL, P < 0.0001). One month after the booster, 99.7% of subjects in the EB group and 99.6% in the RB group had a detectable anti-HBs, and 99.0 and 99.3%, respectively, had anti-HBs > or =10 mIU/mL. The anti-HBs GMT was 113,201 mIU/mL in the EB and 16,623 mIU/mL in the RB groups (P < 0.0001). One year after the booster, 99.3% of subjects in the EB group and 100% in the RB group had detectable anti-HBs, and 97.9 and 98.5% respectively, had anti-HBs > or =10 mIU/mL. The anti-HBs GMT was 14,028 mIU/mL in the EB and 3437 mIU/mL in the RB group (P < 0.0001).

CONCLUSIONS

The immunity persists for at least 5 years after the primary vaccination with both pediatric vaccines in 99% of children vaccinated at the age of 8-10 years. It confirms that no booster is needed at that point.

Recombinant hepatitis B vaccine (Engerix-B): a review of its immunogenicity and protective efficacy against hepatitis B

Engerix-B (Hep-B[Eng]) is a noninfectious recombinant DNA vaccine containing hepatitis B surface antigen (HBsAg). It is produced from genetically engineered yeast (Saccharomyces cerevisiae). Intramuscular Hep-B(Eng) [0-, 1-, 6-month schedule] has excellent immunogenicity in healthy neonates and infants, children, adolescents and adults, with seroprotection rates of 85-100% seen approximate, equals 1 month after the final dose of vaccine; seroprotection was defined as an antibody against HBsAg (anti-HBs) titre of > or =10 IU/L. The use of alternative Hep-B(Eng) immunisation schedules (e.g. a 0-, 1-, 2-, 12-month schedule in neonates and infants, 0-, 12-, 24-month or two-dose schedules in children and adolescents, and accelerated schedules in adults) have also been associated with high rates of seroprotection. Seroprotection rates were generally similar with Hep-B(Eng) and the recombinant vaccine Recombivax HB (Hep-B[Rax]) or plasma-derived vaccines (PDVs) approximate, equals 1 month after the final dose (although anti-HBs geometric mean titres were significantly higher with Hep-B[Eng] than with Hep-B[Rax]). One month after the final dose, adults had significantly higher seroprotection rates with the recombinant triple-antigen vaccine Bio-Hep-B (Hep-B[Bio]) than with Hep-B(Eng), although seroprotection rates in healthy infants were similar with Hep-B(Eng) and Hep-B(Bio). Hep-B(Eng) had excellent immunogenicity in several groups considered at high risk of acquiring hepatitis B (e.g. neonates born to hepatitis B carrier mothers and healthcare workers). The immunogenicity of Hep-B(Eng) was reduced in patients with conditions associated with impaired immune function (e.g. patients undergoing haemodialysis or being treated for malignancy), although it had good immunogenicity in patients with diabetes mellitus.Hep-B(Eng) had excellent protective efficacy against HBsAg carriage in healthy infants and children, and in neonates born to hepatitis B carrier mothers (protective efficacy of 95-99%). Hep-B(Eng) also demonstrated good protective efficacy in a number of other high-risk groups. Hep-B(Eng) is generally well tolerated with a tolerability profile similar to that of Hep-B(Rax), Hep-B(Bio) and PDVs. In conclusion, Hep-B(Eng) is a well established, highly immunogenic hepatitis B vaccine with good tolerability and excellent protective efficacy; it offers flexibility through a variety of immunisation schedules. In addition, it appears that Hep-B(Eng) confers immunity for at least 10 years. Hep-B(Eng) has an important role in mass vaccination campaigns against hepatitis B, as well as in groups considered at high risk of acquiring hepatitis B.

Effectiveness and cost comparison of two strategies for hepatitis B vaccination of schoolchildren

CONTEXT

In 1994, immunization against hepatitis B was implemented in schools in Quebec, targeting grade 4 students. In 1996-1997 and 1997-1998, one Local Community Service Centre (CLSC) replaced the school-based program in its district with vaccination offered in community clinics after school hours. The aim of the current study was to compare the effectiveness and costs of school-based and clinic-based programs.

METHODS

Vaccination coverage data were collected in the CLSC with the clinic-based program (CBP), and in three matched CLSCs with a school-based program (SBP), from 1994 to 2000. Surveys were conducted to estimate costs to parents, to schools and to CLSCs in 1997-1998.

RESULTS

With the implementation of the CBP, the vaccination coverage fell to 73%, compared with over 90% in the SBPs. Coverage increased to 90% when the CBP was abandoned. Costs to the CLSC were not much lower in the CBP. Societal costs were $63 per student vaccinated in the CBP, and < or = $40 in the SBPs.

CONCLUSION

Results demonstrate the advantage of a SBP over a CBP for the immunization of schoolchildren.

Preadolescent non- and hyporesponders following three doses of hepatitis B vaccine need only one more dose

A small proportion of healthy children fail to develop antibodies against hepatitis B after three doses of vaccine. Few data are available regarding the optimal re-immunization strategy. We measured the immune response 1 month after a single supplementary dose of recombinant hepatitis B vaccines in 18 young preadolescents who were non- or hyporesponsive after a regular primary course of three doses of recombinant hepatitis B vaccines. Among them, 100% seroconverted and 89% reached the seroprotective titer of 10 milli-International Units (mIU)/ml. Most healthy children, particularly if they are hyporesponders, will have reached the seroprotective level after one dose and will not need further injections.

Anti-HBs response to standard hepatitis B vaccination in children and adolescents with diabetes mellitus

Patients with type 1 diabetes mellitus are expected to respond poorly to hepatitis B (HB) vaccination. In this study we tested this hypothesis for the standard vaccination schedule. Ninety-nine patients (age 10.8 +/- 3.5 years) were vaccinated against HB (10 pg/dose at 0, 1, and 6 months) using a vaccine containing no pre-S2 antigen (Engerix Bs). The sero-conversion and -protection rates after the completion of three doses, the relation of anti-HBs titers to clinical parameters, and comparison with those of healthy counterparts (51 children, aged 9.7 +/- 4.4 years) were analyzed. The vaccine used was pre-S2 antigen containing (Genhevac B) in 23 and Engerix B in 28; both types yielded a similar response. The geometric mean of the anti-HBs titer was 322.9 vs 1476.8 IU/l (non-significant), sero-convertion rate 96.9% vs 100%, and seroprotection rate 93.9% vs 99% in the diabetic and control groups, respectively. In the diabetic group, there was no correlation between anti-HBs titer and clinical characteristics except for age. We concluded that the standard vaccination schedule is less effective but still effective enough in children and adolescents with type 1 diabetes mellitus.

Most ten-year-old children with negative or unknown histories of chickenpox are immune

To evaluate the proportion of children to vaccinate against varicella in a catch-up program targeting 9- to 10-year-old children, a study was conducted among children age 10 years to assess the age-specific incidence of varicella and document the immunity against varicella in those with negative or unknown chickenpox history. Of the latter 62% were seropositive for varicella.

Serologic response to hepatitis B vaccine in HIV infected and high-risk HIV uninfected adolescents in the REACH cohort. Reaching for Excellence in Adolescent Care and Health

PURPOSE

To evaluate hepatitis B (HBV) vaccine response rates in HIV infected and high-risk HIV uninfected youth and examine associations with responsiveness in the HIV infected group.

METHODS

Cohorts within the Reaching for Excellence in Adolescent Care and Health (REACH) study population were defined based on receipt of HBV vaccine both retrospectively and prospectively. Sero-responsiveness was determined by HBsAb measurements. Testing was done for HBsAg, HBsAb, and HBcAb. For HBsAb, a value of > 10 International Units per liter was considered a positive response, and the data were collected as either positive or negative from each of the reporting laboratories. Covariates of responsiveness were explored in univariate and multivariate models for each cohort.

RESULTS

Sixty-one subjects had received a three-dose vaccination course at the time of entry into REACH. HIV uninfected subjects had significantly higher rates of response by serology compared with HIV infected subjects (70% vs. 41.1%; chi(2) = .05; RR = .586, 95% CI: .36-.96). By the time of an annual visit 43 subjects had received three vaccinations with at least one occurring in the study period. The rates of response were similar for the HIV infected and uninfected groups (37.1% vs. 37.5%) in this cohort. Univariate and multivariate analysis in the prospective HIV infected group (N = 35) found an association between elevated CD8(+)/CD38(+)/HLA-DR(+) T cells and lack of HBV vaccine responsiveness (6.7% vs. 60%; chi(2) = .03; RR = .12, 95% CI: .02- .55).

CONCLUSIONS

The poor HBV vaccine response rate in the HIV uninfected high-risk adolescents was unexpected and suggests that HBV vaccination doses have not been optimized for older adolescents. This is the first report of decreased responsiveness in HIV infected subjects being associated with elevated CD8(+)/CD38(+)/HLA(-)DR(+) T cells and suggests that ongoing viral replication and concomitant immune system activation decreases the ability of the immune system in HIV infected subjects to respond to vaccination.

High seroprotection rate induced by low doses of a recombinant hepatitis B vaccine in healthy Iranian neonates

Low-dose vaccination has been proposed as a cost-saving strategy to implement mass vaccination of neonates with hepatitis B (HB) vaccine, world-wide, particularly in developing countries. The effectiveness of low vaccine doses, however, needs to be evaluated and verified in newborns from different ethnic backgrounds. In this study, a recombinant HB vaccine (Heberbiovac) was administered in three different doses, including the standard 10 microg together with 5 and 2.5 microg to three groups of healthy Iranian neonates. Each group, consisting of 230-260 subjects, received triple doses of vaccine given i.m. at 0, 1.5 and 9 month intervals. Serum samples were collected 2-4 weeks after completion of vaccination, and anti-HBs antibody was quantitated by a sandwich ELISA. Seroprotection (anti-HBs>10 IU/L) was detected in 92, 97.4 and 96.1% of 2.5, 5 and 10 microg vaccine dose recipients, with geometric mean titer (GMT) of 4502, 5824 and 6104 IU/L, respectively. No significant differences were observed in seroprotection rate and GMT between the 10 and 5 microg dose recipients. Both parameters, however, were significantly lower in neonates vaccinated with a 2.5 microg vaccine dose (P<0.05 and P<0.001, respectively). These findings indicate induction of a strong protective immune response in healthy Iranian neonates by a low dose (5 microg) of the recombinant HB vaccine.

Opinions of Quebec parents and vaccinators on the usefulness of chickenpox vaccine

BACKGROUND

A chickenpox vaccine was recently licensed in Canada. Because this vaccine has caused some controversy within the health care profession, studies among Quebec parents and vaccine providers were carried out, surveying their opinions concerning chickenpox vaccination.

METHODS

Three studies among parents of preadolescents, parents of two-year-old children completely or incompletely vaccinated and vaccinators were completed. The studies asked for opinions concerning the usefulness of vaccinating children against chickenpox.

RESULTS

The majority of parents of preadolescents (56%), and parents of two-year-old children completely (64%) and incompletely vaccinated (60%) favoured chickenpox vaccination. Among vaccinators, 53% of paediatricians, 37% of general practitioners and 33% of nurses considered universal vaccination of young children to be useful. A greater proportion of health care professionals were in favour of a policy of vaccinating groups at risk, such as susceptible adolescents (86%, 75% and 58%, respectively). There was a positive association between the perceived severity of chickenpox and the potential usefulness of the vaccine.

CONCLUSION

Quebec parents are more favourably disposed to chickenpox vaccine than vaccine providers. In contrast, strategies targeting susceptible groups would be generally well received by health care professionals. A considerable amount of work will be needed to convince vaccinators of the benefits of a universal childhood vaccination against chickenpox.

Hepatitis B vaccines: assessment of the seroprotective efficacy of two recombinant DNA vaccines

BACKGROUND

In universal vaccination programs, when there is no postvaccination sero-1 logic assessment of response, there must be confidence that the vaccines used provide a high degree of seroprotection.

OBJECTIVE

This parallel analysis of 2 recombinant hepatitis B vaccines (Engerix B and Recombivax/HB-Vax II) was conducted to review the seroprotective efficacy of each vaccine in defined populations.

METHODS

Clinical studies of the 2 vaccines published as manuscripts or conference abstracts in the public domain between January 1986 and April 1999 were identified retrospectively by unrestricted screening of journals through BIOSIS, MEDLINE, and EMBASE and the Internet. Unpublished or internal company data were excluded to maintain impartiality. The studies were reviewed and analyzed. The studies were not assessed for quality other than a judgment of their eligibility for inclusion in the analysis. The primary outcome measure was the proportion of subjects in defined populations who showed an early seroprotective response to currently licensed vaccination schedules. Summary statistical analyses of seroprotective response rates and 95% CIs were calculated for each vaccine for each population. Seroprotective response was defined by an anti-hepatitis B surface antigen titer > or =10 IU/L measured between 1 and 3 months after the final vaccination. Because the study was designed specifically to review published immunogenicity data, safety data were not assessed. The study was not designed to demonstrate superiority of one vaccine over the other.

RESULTS

A total of 181 clinical studies representing 32,904 vaccinated subjects were reviewed and analyzed, of whom 24,277 had been vaccinated with Engerix B and 8627 vaccinated with Recombivax/ HB-Vax II. Seroprotection was achieved in 20,060 subjects (95.8%) with Engerix B and in 7774 subjects (94.3%) with Recombivax/HB-Vax II in the normal population vaccinated according to currently licensed 3-dose schedules. In a subgroup analysis, response rates in health care workers were 6492 subjects (94.5%) for Engerix B and 3245 subjects (92.2%) for Recombivax/HB-Vax II. Children and adolescents (1-19 years) showed the highest response rates to vaccination (4612 [98.6%], Engerix B; 2292 [98.9%], Recombivax/HB-Vax II). A total of 2875 infants (<1 year) (95.8%) achieved seroprotection with Engerix B; 701 (88.5%) achieved seroprotection with Recombivax/ HB-Vax II.

CONCLUSIONS

Hepatitis B vaccination programs using either Engerix B or Recombivax/HB-Vax II can achieve high seroprotective response rates, particularly in childhood and adolescence. Ideally, younger populations should be a primary target in current universal vaccination programs.

Antibody-response to three recombinant hepatitis B vaccines: comparative evaluation of multicenter travel-clinic based experience

The immunogenicity of three currently used hepatitis B vaccines was compared in an unselected study population in an every day travel clinical setting. Five hundred and eighteen vaccinees received Engerix-B (EB), 990 received Twinrix (TWX), and 366 were immunised with Gen-HB-Vax (GHB). Overall, 88.6% of the vaccinees, tested within the first 6 months after completion of the vaccination series, developed protective levels of anti-HBs (> or = 10 mIU/ml). However, GHB recipients showed significantly lower seroprotection rates (SPR) than EB and TWX recipients (79.3% vs. 87.7% vs. 92.3%, P < 0.000001). GMTs for anti-HBs, tested within 6 months after the third vaccination, showed the lowest results in the GHB group, followed by EB and TWX (142 vs. 523 vs. 1008 mIU/ml, P < 0.000001). TWX vaccinees, however, showing a higher antibody decline rate than EB recipients within the first years after completion of the full immunisation course (30% vs. 25%; P = 0.0538). This study confirms an overall good immune response to the 20 microg-dose vaccine, in the course of a regular clinical setting. The significant difference in SPRs and GMTs to the 10 microg-dose vaccine, however, may influence future immunisation practices for the elderly.

Importance of attributable risk in monitoring adverse events after immunization: hepatitis B vaccination in children

OBJECTIVES

Most vaccine safety data present only the postvaccination incidence of all adverse events rather than an estimate of attributable risk. This study sought to illustrate the difference between the 2 estimates with data from a hepatitis B immunization program.

METHODS

The incidence of health problems occurring before and after each dose of hepatitis B vaccine in a cohort of 1130 children were compared.

RESULTS

Although 47.5% of all children reported an adverse event during the 4 weeks following each of the 3 doses, adverse events attributable to immunization occurred in only 10.6% of children.

CONCLUSIONS

Postimmunization incidence systematically overestimates the risk of adverse events. Estimating actual attributable risk is necessary to avoid false beliefs regarding immunization.