Persistence of specific antibodies after hepatitis B vaccination

The persistence of seroprotective levels of antibodies after vaccination with PreHevbrio, a 3-antigen hepatitis B vaccine

Prevention of hepatitis B virus (HBV) infection by vaccination can potentially eliminate HBV-related diseases. PreHevbrio™/PreHevbri® is a 3-antigen (S, preS1, preS2) HBV vaccine (3A-HBV) recently licensed for adults in the US, EU and Canada. This study evaluated antibody persistence in a subset of fully vaccinated and seroprotected (anti-HBs ≥ 10 mIU/mL) Finnish participants from the phase 3 trial (PROTECT) of 3A-HBV versus single-antigen HBV vaccine (1A-HBV). 465/528 eligible subjects were enrolled (3A-HBV: 244; 1A-HBV: 221). Baseline characteristics were balanced. After 2.5 years, more 3A-HBV subjects remained seroprotected (88.1 % [95 %CI: 84.1,92.2]) versus 1A-HBV (72.4 % [95 %CI: 66.6,78.3)], p < 0.0001) and had higher mean anti-HBs [1382.9 mIU/mL (95 %CI: 1013.8,1751.9) versus 252.6 mIU/mL (95 %CI: 127.5,377.6), p < 0.0001]. In multiple variable logistic regression analysis including age, vaccine, initial vaccine response, sex and BMI, only higher post dose 3 (Day 196) antibody titers significantly reduced the odds of losing seroprotection.

Hepatitis B Vaccination: A Historical Overview with a Focus on the Italian Achievements

Vaccination is the most effective way to control and prevent acute and chronic hepatitis B, including cirrhosis and HCC, on a global scale. According to WHO recommendations, 190 countries in the world have introduced hepatitis B vaccination into their national childhood immunization programs with an excellent profile of safety, immunogenicity, and effectiveness. Following vaccination, seroprotection rates are close to 100% in healthy children and over 95% in healthy adults. Persistence of anti-HBs is related to the antibody peak achieved after vaccination. The peak is higher the longer the antibody duration is. Loss of anti-HBs does not necessarily mean loss of immunity since most vaccinated individuals retain immune memory for HBsAg and rapidly develop strong anamnestic responses when boosted. Evidence indicates that the duration of protection can persist for at least 35 years after priming. Hence, booster doses of vaccines are currently not recommended to sustain long-term immunity in healthy vaccinated individuals. In Italy, vaccination against hepatitis B is met with success. In 2020, Italy became one of the first countries in Europe to be validated for achieving the WHO regional hepatitis B control targets.

The impact of glucose tolerance state on seropositivity rate after hepatitis B vaccination

Immunization is recommended for people with diabetes mellitus (DM), but little information is available on their seropositivity rates. To determine the impact of glucose tolerance state on seropositivity rate after hepatitis B vaccination, we included 7645 adult participants from the National Health and Nutrition Examination Survey 2005-2016 who reported three doses of hepatitis B vaccine and were seropositive for anti-hepatitis B surface antibody (≥ 12.0 mIU/mL), after exclusion of those positive for anti-hepatitis B core antibody and/or hepatitis B surface antigen. We classified the states of glucose tolerance as normal glucose tolerance (NGT, 61.68%), abnormal glucose tolerance (AGT, 26.02%), or DM (13.30%). We observed a stepwise decline in hepatitis B seropositivity rate from NGT (53.64%) to AGT (45.52%) to DM (28.84%) (P < 0.0001). We confirmed these results after standardization for age and BMI (P < 0.0001 for all subgroup analyses) and in subgroup analyses by gender and racial/ethnic group. Dysregulated glucose metabolism is associated with a decreased seropositivity rate after hepatitis B vaccination. Our observations suggest that regular follow-up screening for anti-hepatitis B surface antibody, with additional booster vaccination as necessary, is especially important in patients with DM. Whether a similar phenomenon exits for other vaccines, especially COVID-19, remains to be investigated.

Developments in Vaccine Adjuvants

Vaccines, including subunit, recombinant, and conjugate vaccines, require the use of an immunostimulator/adjuvant for maximum efficacy. Adjuvants not only enhance the strength and longevity of immune responses but may also influence the type of response. In this chapter, we review the adjuvants that are available for use in human vaccines, such as alum, MF59, AS03, and AS01. We extensively discuss their composition, characteristics, mechanism of action, and effects on the immune system. Additionally, we summarize recent trends in adjuvant discovery, providing a brief overview of saponins, TLRs agonists, polysaccharides, nanoparticles, cytokines, and mucosal adjuvants.

Persistence of Anti-Hbs after up to 30 Years in Health Care Workers Vaccinated against Hepatitis B Virus

The burden of hepatitis B virus (HBV) infection is a serious public health problem all over the world. Vaccination remains the most effective prevention measure, and safe and effective HBV vaccines have been available since 1982. Health care workers (HCWs) vaccinated against HBV and prospectively followed up for at least 14 years were classified by their antibody titers after primary vaccination as: poor responders (10–99 mIU/mL); moderate responders (100–999 mIU/mL); and good responders (≥1000 mIU/mL). The incidence of antibody loss was calculated for 1000 person-years and the anti-HBs persistence was calculated. The analysis concerned 539 HCWs: 494 good responders (91.7%); 37 moderate responders (6.9%); and eight poor responders (1.5%). The incidence of anti-HBs loss was 52.1 per 1000 person-years for the poor responders, 11.3 per 1000 person-years for the moderate responders, and 1.4 per 1000 person-years for the good responders. The mean persistence of anti-HBs differed significantly between the three groups, being: 19.2 years (95% CI: 15.6–22.8), 25.4 years (95% CI: 23.0–27.9), and 31.0 years (95% CI: 30.5–31.5) for the poor, moderate and good responders, respectively. In conclusion, our findings demonstrate a good persistence of protective anti-HBs titers in HCWs exposed to occupational risk for up to 30 years after a primary vaccination cycle (even without a booster dose) if their titer was initially higher than 100 mIU/mL.

Development of the CpG Adjuvant 1018: A Case Study

The development of aluminum salts (alum) as vaccine adjuvants was an empirical process with little understanding of the mechanism of action and, with decades of use, it has become clear that there is a need for alternatives where alum-based adjuvants are suboptimal. Oligonucleotides containing unmethylated CpG sequences represent one alternative as they are potent stimulators of the vertebrate innate immune system through activation of Toll-like receptor-9. This chapter outlines the methods used by Dynavax Technologies to progress a CpG-containing oligonucleotide sequence termed 1018 through preclinical and clinical testing as an adjuvant for immunization against hepatitis B virus (HBV). 1018 is a short (22-mer) oligonucleotide sequence containing CpG motifs active in both rodents and primates. Preclinical testing of hepatitis B surface antigen (HBsAg) + 1018 in comparison to HBsAg + alum demonstrated induction of substantially higher antibody titers and a favorable safety profile for 1018. Most importantly, clinical studies with HBsAg vaccination consistently demonstrate more rapid induction of protective antibody titers with 1018 compared to alum in all populations studied, including groups that are harder to immunize such as the elderly and immunocompromised individuals. These studies represent the basis for use of the CpG-motif-containing oligonucleotide 1018 as an improved adjuvant for HBsAg immunogenicity. HBsAg + 1018 (HEPLISAV-B^™) is currently in late-stage clinical testing for prophylactic immunization against HBV.

Hepatitis B immune status in adolescents vaccinated during infancy: A retrospective cohort study from a pediatric practice in Germany

In Germany, vaccination of infants against hepatitis B is recommended since 1995. However, data on long-term immunity is sparse and the necessity of a booster dose remains uncertain. Aims of this study were to assess the long-term persistence of antibodies to the hepatitis B surface antigen (anti-HBs) after immunization during infancy and the effect of a subsequent hepatitis B booster vaccination during adolescence on anti-HBs levels. Patients from a private pediatric practice who had received a full vaccination course of hepatitis B as infants and who were quantitatively tested for anti-HBs during adolescence (pre-booster levels) were included. In those participants who received a hepatitis B booster, post-booster anti-HBs levels were measured. Univariate analyses were conducted to determine factors associated with pre- and post-booster anti-HBs levels, respectively. 106 participants (53% male) were included in the study. At an average of 13.7 y after primary vaccination, 14% of participants had an anti-HBs level of ≥100 IU/l, while 46% were at 10-99 IU/l and 40% had anti-HBs levels of <10 IU/l. In total, 34 received a booster vaccination. Of those, 97% (33/34) had post-booster anti-HBs levels ≥ 100 IU/l, which were independent from pre-booster levels. No other patient characteristics were associated with pre-booster or post-booster anti-HBs≥ 100 IU/l. Although almost half of study participants showed low anti-HBs levels at follow-up, robust responses to booster vaccination suggest that adolescents who received the full vaccination course during infancy are still protected against hepatitis B infection.

Suitable hepatitis B vaccine for adult immunization in China

The aim of this study was to evaluate, in adults, the immunogenicity of six hepatitis B vaccines with different doses or different manufacturers in the Chinese market and to provide evidence to support adult hepatitis B vaccination. Participants were randomly divided into six groups (I–VI). Six vaccines (4 at 10 μg/dose and 2 at 20 μg/dose) were administered intramuscularly to healthy adults at 0, 1 and 6 month intervals. All participants (16–50 years) who were negative for any hepatitis B virus serological markers were vaccinated. Anti-HBs levels were assessed 1 month and 1 year after the third vaccination. The anti-HBs seroconversion rate (anti-HBs >10mIU/ml) was 99.4 % (99.9 % for 10 μg dose groups and 97.9 % for 20 μg dose groups) 1 month after the third vaccination, and the anti-HBs seroreversion rate was 77.0 % (75.3 and 82.6 %) 1 year after the third vaccination (n = 1036). One month after completing the vaccinations, the seroconversion rates were not significantly different (100.0, 100.0, 99.6, 100.0 %) for the four 10 μg dose and two 20 μg dose groups (99.1, 96.9 %). One year after the third vaccination, the group II positive rate was significantly higher than the other three 10 μg dose groups, and the group VI positive rate was significantly higher than the other 20 μg dose group. Groups II and VI showed a significantly higher positive rate and anti-HBs geometric mean titer (GMT) than the other groups. The anti-HBs level declined with increasing age, and the seroreversion rate and GMT decreased over time. All six vaccines had high anti-HBs seroconversion rates and good immunization effects. The 10 μg dose vaccine (Dalian High-Tech) and the 20 μg dose vaccine (GlaxoSmithKline) are recommended for adults.

Durability of antibody response against hepatitis B virus in healthcare workers vaccinated as adults

BACKGROUND

Follow-up studies of recipients of hepatitis B vaccine from endemic areas have reported loss of antibody to hepatitis B surface antigen (anti-HBs) in a high proportion of persons vaccinated at birth. In contrast, the long-term durability of antibody in persons vaccinated as adults in nonendemic areas is not well defined. We aimed to assess the durability of anti-HBs among healthcare workers (HCWs) vaccinated as adults and response to a booster among those without protective levels of antibody.

METHODS

Adult HCWs aged 18-60 at the time of initial vaccination were recruited. All were tested for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc), and anti-HBs level. HCWs with anti-HBs <12 mIU/mL were offered a booster and levels were measured 1, 7, and 21 days afterward.

RESULTS

Anti-HBs levels were <12 mIU/mL in 9 of 50 (18%), 13 of 50 (26%), and 14 of 59 (24%) HCWs 10-15, 16-20, and >20 years postvaccination, respectively, (P = ns). Four HCWs were anti-HBc positive; none had HBsAg. By logistic regression, older age at vaccination was the only predictor of inadequate anti-HBs level (P = .0005). Thirty-four of 36 subjects with inadequate anti-HBs levels received a booster and 32 (94%) developed levels >12 mIU/mL within 3 weeks.

CONCLUSIONS

Anti-HBs levels decrease after 10-31 years and fall below a level considered protective in approximately 25% of cases. The rapid and robust response to a booster vaccine suggests a long-lasting amnestic response. Hepatitis B vaccination provides long-term protection against hepatitis B and booster vaccination does not appear to be necessary in HCWs. Clinical Trials Registration. NCT01182311.

Seroepidemiology of hepatitis B virus infection among adults in Singapore: a 12-year review

We undertook a national hepatitis B seroprevalence study to assess the seroprevalence of hepatitis B virus (HBV) markers in the adult population in Singapore in 2010 and make comparisons with the seroprevalence in 1998 and 2004. The study involved residual sera from national health surveys conducted every six years since 1998. The tests for HBV markers were carried out using commercial chemiluminescent microparticle immunoassay. In 2010, the prevalence of hepatitis B surface antigen (HBsAg) among 3293 Singapore residents aged 18-79 years was 3.6% (95% confidence interval [CI] 2.9-4.2%). Hepatitis B e antigen (HBeAg) was detected in 4.2% of those who were HBsAg positive. About 22.5% (95% CI 21.1-23.9%) were positive for antibody to hepatitis B core antigen (anti-HBc). The overall population immunity to HBV, as determined by antibody to hepatitis B surface antigen (anti-HBs)≥ 10 mIU/mL, was 43.9% (95% CI 42.2-45.6%). Among young adults below 30 years of age, HBsAg prevalence (1.1%) was half that in 1998 and 2004, and in those positive for HBsAg, none was positive for HBeAg in 2010, compared to 20.8% in 1998 and 15.8% in 2004. In this age group, anti-HBc prevalence also decreased significantly from 22.1% in 2004 to 4.4% in 2010, while anti-HBs (≥ 10 mIU/mL) prevalence increased significantly from 27.9% in 1998 to 43.3% in 2010 (p<0.001). The national childhood HBV immunisation and catch-up programmes implemented in 1987 and 2001-2004, respectively, had a significant impact in reducing HBV infection and in raising the immunity of the adult population 18-29 years of age.

An assessment of the performance of self-reported vaccination status for hepatitis B, National Health and Nutrition Examination Survey 1999-2008

OBJECTIVES

We sought to assess the performance of self-reported vaccination with hepatitis B vaccine (HepB) compared with serological status for hepatitis B markers in the general US civilian population.

METHODS

Using 1999 through 2008 National Health and Nutrition Examination Survey data, we calculated 3 measures of agreement between self-reported HepB vaccination status and serological status: percent concordance, and positive (PPV) and negative predictive values (NPV) of self-report. Logistic regression was used to identify factors associated with agreement between self-report and serological status.

RESULTS

Overall agreement was 83% (95% CI = 82.3, 83.7), NPV of self-report was high (0.95; 95% CI = 0.93, 0.95) and PPV was low (0.53; 95% CI = 0.51, 0.54). Birth year relative to the 1991 recommendation for universal infant HepB vaccination had a strong association with agreement, however, the association was positive for those who reported receiving at least 3 doses and negative for those who reported receiving no doses.

CONCLUSIONS

Although the low PPV in our study could be attributable in part to waning of vaccine-induced anti-HBs over time, national adult HepB vaccination coverage may be lower than previously estimated because national estimates usually depend on self-report of vaccine receipt.

Immunological effects of a 10-μg dose of domestic hepatitis B vaccine in adults

OBJECTIVE

To evaluate the immunological effects of three types of domestic 10-µg/dose hepatitis B vaccines in adults compared with a foreign vaccine, and to provide scientific evidence in support of adult hepatitis B vaccination.

METHODS

Adults from five counties (Deqing, Changxing, Nanxun, Wuxing, Anji) in Huzhou City, Shaoxing County and Tongxiang County, Zhejiang Province, China were selected. Blood samples were taken to assess serum HBsAg, anti-HBs, and anti-HBc using a chemiluminescence immunoassay. Adults, aged 16 to 49 years and who were anti-HBs negative at baseline, received hepatitis B immunizations at 0, 1, and 6 months. Anti-HBs levels were assessed one month after the third and final vaccination.

RESULTS

A total of 1872 adults were immunized and the average positive rate was 89.5%. Four types of hepatitis B vaccine were used, including three from Chinese companies (Shenzhen Kangtai, Dalian High-Tech, and North China Pharmaceutical) and one from a UK company (GlaxoSmithKline). Their seroconversion rates were 81.67%, 95.05%, 89.64%, and 86.81%, respectively. There was a significant difference between the anti-HBs positive conversion rates of the four types (P<0.005) but the seroconversion rates among the different vaccines were not significantly different (χ(2)=2.123, P=0.145). The average anti-HBs geometric mean titers (GMTs) of non-immune adults immunized with each of the four vaccines were 177.28, 473.23, 246.13, and 332.20 mIU/ml, respectively. There were no statistically significant differences in the GMTs between the three types of domestic vaccine and the foreign vaccine (t=-1.575, P=0.116).

CONCLUSIONS

Domestic recombinant hepatitis B vaccines can achieve immunization effects comparable to those of a foreign vaccine.

Brazilian hepatitis B vaccine: a six-year follow-up in adolescents

The protective anti-HBs titres were examined six-year post-immunisation with the Brazilian recombinant hepatitis B vaccine. After the primary vaccination, all adolescents (n = 89) responded with protective anti-HBs titres and had a geometric mean titre (GMT) of 4031.8 mIU/mL. In 2010, 94.5% maintained protective anti-HBs (> 10 mIU/mL) antibodies, with a GMT of 236.0 mIU/mL. A positive correlation was observed between the anti-HBs titres after the primary vaccination and the titres at the six-year follow-up (p < 0.01). Eleven subjects showed anti-HBs titres suggestive of a natural booster. Prostitution and tattoos/piercings were marginally associated with natural boosters in the multivariate analysis. This study showed the first data on anti-HBs persistence following the Brazilian hepatitis B vaccine in sexually active individuals and highlights its effectiveness in the medium term.

Seroprevalence of hepatitis B virus infection among children and adolescents in Singapore, 2008-2010

A national pediatric survey was undertaken to determine the prevalence of hepatitis B virus markers in Singapore. The aim was to assess the impact of the national childhood immunization program against hepatitis B implemented for all newborns since 1987. The survey involved prospective collection of residual sera from Singapore residents aged 1-17 years attending inpatient services or day surgery in two public hospitals between August 2008 and July 2010. A total of 1,200 sera were collected comprising 400 in each of the three age groups of 1-6, 7-12, and 13-17 years. The sera were tested for hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). Four of the 1,200 samples tested positive for HBsAg, giving an overall prevalence of 0.3%. One and three in the 7-12 years and 13-17 years age groups, respectively, were positive for HBsAg. About 40% possessed anti-HBs (≥10 mIU/ml); the antibody prevalence decreased significantly from 63.8% in children aged 1-6 years to 32.8% in 7-12 year olds, and 23.5% in 13-17 year olds (P < 0.0005). The successful implementation of the national childhood hepatitis B immunization program over the last two decades has resulted in a low prevalence of HBsAg among children and adolescents. Singapore has achieved the World Health Organization Western Pacific Region's goal in reducing the prevalence of chronic HBV infection to below 2% among children aged 5 years and older by 2012 and to below 1% by 2017.

Demonstration of safety and enhanced seroprotection against hepatitis B with investigational HBsAg-1018 ISS vaccine compared to a licensed hepatitis B vaccine

Adults 40 years of age and older have been shown to be hypo-responsive immunologically to the currently available hepatitis B virus (HBV) vaccines. Three intramuscular doses of a Toll-like receptor 9 agonist, 1018 immunostimulatory sequence (1018 ISS) adjuvant, combined with recombinant hepatitis B surface antigen (HBsAg) demonstrated faster, superior, and more durable seroprotection than three doses of a licensed comparator HBV vaccine (Engerix-B(®)). This investigational vaccine, HBsAg-1018 ISS, was well tolerated with a safety profile similar to the comparator vaccine. These results suggest that HBsAg-1018 may be more effective in this hypo-responsive population.

Persistence of long-term immunity to hepatitis B among adolescents immunized at birth

The long-term duration of recombinant hepatitis B vaccine-induced immunity among persons vaccinated starting at birth is still not well understood. Waning of vaccine-induced immunity could leave young adults at risk of hepatitis B virus infection due to behavioral or occupational exposures. We followed a cohort of children immunized starting at birth with a 3-dose regimen of recombinant hepatitis B vaccine (5 mcg, 2.5 mcg, 2.5 mcg). They were challenged with a booster dose of the hepatitis B vaccine 10 and 15 years after vaccination to assess anamnestic response as a measure of persistence of protection. Among 108 participants who had lost protective antibody levels against hepatitis B, the majority (>70%) had an anamnestic response to the booster dose; response rates did not decline significantly between 10 and 15 years follow-up periods. A high antibody concentration following primary vaccination was independently associated with an anamnestic response later on in life. Nonetheless, ~20-30% of participants were unable to mount an immune response after boosting. Hepatitis B revaccination might be required for persons vaccinated starting at birth if opportunities for hepatitis B virus exposure exist. Future vaccine recommendations should be based on studies ascertaining protection against clinically significant disease.

Persistence of immune response to HPV-16/18 AS04-adjuvanted cervical cancer vaccine in women aged 15-55 years

The HPV-16/18 AS04-adjuvanted vaccine (Cervarix®, GlaxoSmithKline Biologicals) has been shown to induce a robust immune response in women aged 15-55 years (103514/NCT00196937). This follow-up study is the first report of persistence of immune response and safety profile through 48 months after vaccination in women aged 15-55 years. In this open-label, age-stratified Phase III study in Germany and Poland (105882/NCT00196937), healthy women aged 15-55 years received 3 doses of HPV-16/18 AS04-adjuvanted vaccine at 0, 1, and 6 months. Anti-HPV-16/18 seropositivity rates and geometric mean antibody titers (GMTs) were assessed by enzyme-linked immunosorbent assay (ELISA) in women aged 15-25 (n=168), 26-45 (n=186) and 46-55 years (n=177) from the time of first vaccination through 48 months. At Month 48, all subjects were seropositive for anti-HPV-16 antibodies and 99.4% were seropositive for anti-HPV-18. Antibody kinetics were as previously reported, with peak response at Month 7 followed by a gradual decline tending towards a plateau in all age groups. Anti-HPV-16/18 GMTs were sustained at Month 48 in all age groups, including women aged 46-55 years in whom GMTs were respectively 11-fold and 5-fold higher than natural infection levels. The vaccine exhibited a clinically acceptable safety profile in all age groups. In summary, the HPV-16/18 AS04-adjuvanted vaccine induces high and sustained immune responses in women aged 15-55 years, with antibody levels remaining several-fold higher than natural infection levels for at least 4 years after the first vaccine dose.

Comparison of a bacteriophage-delivered DNA vaccine and a commercially available recombinant protein vaccine against hepatitis B

A bacteriophage lambda DNA vaccine expressing the small surface antigen (HBsAg) of hepatitis B was compared with Engerix B, a commercially available vaccine based on the homologous recombinant protein (r-HBsAg). Rabbits (five per group) were vaccinated intramuscularly at weeks 0, 5 and 10. Antibody responses against r-HBsAg were measured by indirect enzyme-linked immunosorbent assay, by limiting dilutions and by subtyping. Specific lymphocyte proliferation in vitro was also measured. After one vaccination, three of the five phage-vaccinated rabbits showed a strong antibody response, whereas no r-HBsAg-vaccinated animals responded. Following two vaccinations, all phage-vaccinated animals responded and antibody levels remained high throughout the experiment (220 days total). By 2 weeks after the second vaccination, antibody responses were significantly higher (P<0.05) in the phage-vaccinated group in all tests. After three vaccinations, one out of five r-HBsAg-vaccinated rabbit still failed to respond. The recognized correlate of protection against hepatitis B infection is an antibody response against the HBsAg antigen. When combined with the fact that phage vaccines are potentially cheap to produce and stable at a range of temperatures, the results presented here suggest that further studies into the use of phage vaccination against hepatitis B are warranted.

The worldwide impact of vaccination on the control and protection of viral hepatitis B

Viral hepatitis B is a leading cause of acute and chronic liver disease worldwide, including cirrhosis and hepatocellular carcinoma. Vaccination is the most effective measure for controlling and preventing hepatitis B and its severe long-term sequelae. According to the World Health Organization (WHO), by the end of 2008 177 countries had introduced hepatitis B vaccination into their national routine neonatal, infant and/or adolescent immunisation programmes, and Italy was one of the first countries to implement a universal strategy of hepatitis B vaccination. The implementation of such vaccination programmes has globally resulted in a marked decrease in disease burden, in the carrier rate and in hepatitis B-related morbidity and mortality. Despite this success, work remains to be done to fully achieve the WHO goal of control of hepatitis B and HBV-related diseases on a global scale.

Safety and immunogenicity of an investigational adjuvanted hepatitis B vaccine (HB-AS02V) in healthy adults

HB-AS02 is an investigational adjuvanted hepatitis B virus (HBV) vaccine for potential use in patients with renal insufficiency and other immunocompromized individuals. In this Phase III lot-to-lot consistency study, 450 healthy adult volunteers who had not previously been vaccinated against HBV were randomized to one of three production lots of HB-AS02 at 0 and 1 month and followed until one month after the last vaccine dose. Lot-to-lot consistency was established. High seroprotection rates were already achieved after the first vaccine dose (75.9%). All subjects were seroprotected (anti-HBs antibody concentrations ≥10 mIU/ml) after two doses, with all but one subject achieving anti-HBs antibody concentrations ≥100 mIU/ml (99.7%). Geometric mean anti-HBs antibody concentration was 4594.5 mIU/ml. Local and general symptoms were reported after 80.7% and 45.5% of doses, respectively. However, these were mainly of mild or moderate severity and no subject withdrew from the study due to adverse events.

Randomized trial to determine safety and immunogenicity of two strategies for hepatitis B vaccination in healthy urban adolescents in the United States

BACKGROUND

Multiple studies have shown excellent response rates after hepatitis B immunization in youth; however, one previous study conducted in urban youth demonstrated poor responses.

METHODS

Urban youth, ages 12 to 17 years, at participating Adolescent Medicine Trials Network for HIV/AIDS Interventions Clinical/Research sites were randomized to receive either 2 doses of Recombivax HB (10 microg hepatitis B surface antigen) or Twinrix (20 microg hepatitis B surface antigen and 720 EL.U hepatitis A antigen) at 0 and 24 weeks. Safety data were collected and antibody measures performed at 0, 28, and 76 weeks.

RESULTS

A total of 123 subjects were enrolled and 102 had week 28 serum samples available for antibody measure. A positive response (serum antibody > or =10 mIU/mL) to hepatitis B antigen was documented in 41 of 47 (87.2%; 95% confidence interval [CI] 74.3%-95.2%) Recombivax HB recipients and in 52 of 55 (94.6%; 95% CI, 84.9%-98.9%) Twinrix recipients (P = 0.295). In an adjusted analysis, those identified as Hispanic ethnicity (N = 86) were more likely to have a positive response (odds ratio 7.38, 95% CI, 1.56-34.95; P = 0.0018); whereas those who identified as not heterosexual (N = 9) were less likely to respond (odds ratio = 0.12, 95% CI, 0.02-0.74). The majority of youth in the Twinrix arm were hepatitis A antibody positive at baseline (26/51; 51%); however, 24 of 25 hepatitis A antibody negative youth responded to the hepatitis A component. Both vaccines were safe.

CONCLUSIONS

Response rate to 2 doses of Recombivax HB in urban youth is lower than previous studies suggest. The factors associated with diminished response are not known.

Immunization of guinea pigs with novel hepatitis B antigen as nanoparticle aggregate powders administered by the pulmonary route

Novel nanoparticle-aggregate formulations containing recombinant hepatitis B surface antigen (rHBsAg) were administered to the lungs of guinea pigs and antibodies generated to this antigen evaluated. Preparations of dry powders of: (a) rHBsAg encapsulated within poly(lactic-co-glycolic acid) (PLGA)/polyethylene glycol (PEG) nanoparticles (antigen nanoparticles, AgN(SD)), (b) rHBsAg in a physical mixture with blank PLGA/PEG nanoparticles (antigen nanoparticle admixture (AgNA(SD)), and (c) rHBsAg encapsulated in PLGA/PEG nanoparticles plus free rHBsAg (antigen nanoparticles and free antigen), were generated by spray drying with leucine. Control groups consisted of alum with adsorbed rHBsAg (AlumAg); reconstituted suspensions of spray-dried rHBsAg-loaded PLGA/PEG nanoparticles with leucine; and rHBsAg-loaded PLGA/PEG nanoparticles (AgN). Control preparations were administered by intramuscular injection; AgN was also spray instilled into the lungs. The IgG titers were measured in the serum for 24 weeks after the initial immunization; IgA titers were measured in the bronchio-alveolar lavage fluid. While the highest titer of serum IgG antibody was observed in guinea pigs immunized with AlumAg administered by the IM route, animals immunized with powder formulations via the pulmonary route exhibited high IgA titers. In addition, guinea pigs immunized with AgNA(SD) via the pulmonary route exhibited IgG titers above 1,000 mIU/ml in the serum (IgG titers above 10 mIU/ml is considered protective). Thus, the disadvantages observed with the existing hepatitis B vaccine administered by the parenteral route may be overcome by administering them as novel dry powders to the lungs. In addition, these powders have the advantage of eliciting a high mucosal immune response in the lungs without traditional adjuvants.

Immune response induced by a linear DNA vector: influence of dose, formulation and route of injection

Previously, minimalistic, immunogenetically defined gene expression (MIDGE) vectors were developed as effective and sophisticated carriers for DNA vaccination. Here we evaluate the influence of dose, formulation and delivery route on the immune response after vaccination with MIDGE-Th1 vectors encoding hepatitis B virus surface antigen (HBsAg). An HBsAg-specific IgG1 and IgG2a antibody response was induced in a dose-dependent manner, whereas the IgG2a/IgG1 ratio was independent of the injected DNA dose. Formulation of MIDGE-HBsAg-Th1 with the cationic pyridinium amphiphile SAINT-18 significantly increased antibody levels of IgG1 and IgG2a compared to the unformulated vector. In contrast, SAINT-18 had neither a significant effect on the IgG2a/IgG1 ratio nor on the type and strength of cellular immunity. Overall, the strongest immune response was generated after intradermal injection, followed by intramuscular and subcutaneous (s.c.) injection. The results show that the formulation of MIDGE-Th1 with SAINT-18 increased the efficacy of the MIDGE-Th1 DNA vaccine and is therefore a suitable approach to improve the efficacy of DNA vaccines also in large animals and humans.

Low hepatitis B immunogenicity of a hexavalent vaccine widely used in Germany: results of the German Health Survey for Children and Adolescents, 2003–2006

The success of childhood vaccination against hepatitis B relies on persistence of immunity into adolescence and adulthood. In 2000, two hexavalent vaccines with a hepatitis B component (Hexavac®, Infanrix hexa®) were introduced in Germany. Hexavac was withdrawn in 2005 amidst concerns about its long-term hepatitis B protection. We compared hepatitis B surface antibody (anti-HBs) levels in children fully vaccinated with Hexavac or Infanrix hexa (n=477) in a secondary data analysis of a large cross-sectional health survey in Germany. On average 2·4 years after vaccination, 25·3% of Hexavac vaccinees had anti-HBs levels <10 mIU/ml (95% CI 19·0–32·8) compared to 4·7% of Infanrix hexa vaccinees (95% CI 2·4–8·9). These findings suggest that short-term hepatitis B immunogenicity in Hexavac vaccinees may also be weaker. Further studies are warranted to assess whether Hexavac vaccinees should be re-vaccinated or receive a booster vaccination before these birth cohorts reach adolescence.

Rapid, enhanced, and persistent protection of patients with renal insufficiency by AS02(V)-adjuvanted hepatitis B vaccine

The adjuvanted hepatitis B vaccine, HB-AS04, elicits more rapid and persistent protective antibody concentrations than double doses of conventional recombinant vaccines in patients with renal insufficiency. We compared the immunogenicity, reactogenicity, and safety of the AS02(V)-adjuvanted hepatitis B vaccine HB-AS02 with that of HB-AS04. In this phase III, open, randomized study, 151 hepatitis B vaccine-naïve pre-dialysis, peritoneal dialysis, and hemodialysis patients aged 15 years and older received three doses of HB-AS02 at 0, 1, and 6 months. Another 149 similar patients received four doses of HB-AS04 at 0, 1, 2, and 6 months, and all were followed up for 12 months. HB-AS02 elicited more rapid and persistent seroprotection than HB-AS04, with rates of 77 and 39%, respectively, 1 month after the second vaccine dose, and 94 and 79%, respectively, at 12 months. Superiority of HB-AS02 over HB-AS04 in anti-hepatitis B geometric mean concentrations was found at all time points. HB-AS02 was more reactogenic than HB-AS04, but adverse events were mainly transient, of mild to moderate intensity with no reportable vaccine-related serious events. We conclude that a three-dose primary course of HB-AS02 induced more rapid, enhanced, and persistent protection in patients with renal insufficiency than the licensed four-dose primary schedule of HB-AS04. This adjuvanted vaccine affords greater protection with reduced need for booster doses in patients at high risk of hepatitis B infection.

The global impact of vaccination against hepatitis B: a historical overview

Hepatitis B virus (HBV) infection is a world wide public health problem of major concern. HBV infection may lead to chronic liver disease, including cirrhosis and hepatocellular carcinoma (HCC). Vaccination is the most effective measure to control and prevent hepatitis B and its long-term serious sequelae on global scale, both in terms of cost-effectiveness and benefit-cost ratios. According to the WHO recommendations, universal vaccination has been currently implemented in 168 countries world wide with an outstanding record of safety and efficacy. The effective implementation of such programmes of vaccination has resulted in a substantial decrease in disease burden, in the carrier rate and in hepatitis B-related morbidity and mortality. A future challenge is to overcome the social and economic hurdles which still hamper the introduction of hepatitis B vaccination on a global scale.

A non-randomized vaccine effectiveness trial of accelerated infant hepatitis B immunization schedules with a first dose at birth or age 6 weeks in Côte d'Ivoire

Most African countries do not initiate hepatitis B vaccination at birth. We conducted a non-randomized controlled trial comparing hepatitis B vaccination given at age 0, 6, and 14 weeks versus the current Côte d'Ivoire schedule of 6, 10, and 14 weeks. Pregnant women were enrolled at four health centers in Abidjan. At age 9 months, 0.5% of infants in both the birth and 6-week cohorts were positive for HBsAg and all were born to HBeAg-positive women. Among infants of HBeAg-positive mothers, 9 of 24 (37.5%) in the birth cohort and 10 of 17 (58.8%) in the 6-week cohort were HBsAg positive (adjusted OR, 2.7; 95% CI: 0.7-11.0). While both vaccine schedules prevented most cases of infant HBV transmission, both also had high failure rates among infants of HBeAg-positive mothers. African infants may benefit from a birth dose but additional studies are needed to verify this hypothesis.

A review of the long-term protection after hepatitis A and B vaccination

Vaccine-preventable viral hepatitis continues to be a cause of considerable morbidity and mortality: on worldwide basis, approximately 1.4 million cases of hepatitis A are reported every year. The true incidence, however, has been estimated to be 3-10 times higher. Regarding hepatitis B, more than a third of the world's population has been infected. The World Health Organization has estimated (2000) that there are 367 million chronic carriers of hepatitis B worldwide, and approximately 1 million deaths per year as a consequence of chronic complications and acute fulminant disease. Hepatitis B vaccines have been licensed since 1982, and hepatitis A vaccines since 1992. In 1996, a combined hepatitis A and B vaccine became available. An update on the long-term protection conferred by hepatitis A and hepatitis B vaccines as well as the combined hepatitis A and B vaccine is offered in this paper. Long-term efficacy and booster policy for hepatitis B vaccines have often been a topic of discussion. Based on current data and field experience there is, in general, no necessity for booster doses for fully vaccinated immunocompetent individuals. Long-term protection has been demonstrated by the rapid (5-7 days) development of anamnestic antibody responses among vaccinees who no longer have detectable anti-HBs. Anamnestic responses correlate with lymphoproliferative T-cell responses following challenge with hepatitis B vaccine. Furthermore, employing Spot-ELISA techniques, circulating B-cells were shown to be able to produce anti-HBs in vaccinees who lost their detectable antibodies. The accumulated data from a large number of studies indicate that despite antibody decline or loss, immune memory exhibits long-term persistence. There is somewhat less information available for hepatitis A vaccines, yet an increasing number of studies indicate that the findings for hepatitis B vaccines are also applicable to hepatitis A vaccines. The necessity to provide a booster dose was based on early projections of observed antibody levels. However, recent follow-up studies with up to 12 year observation, as well as studies employing mathematical models predict that following primary vaccination, antibodies will persist for at least 25 years. In addition, experimental studies confirm that vaccination against hepatitis A induces immunological memory. Therefore hepatitis A booster vaccination is presently considered as unnecessary in fully vaccinated individuals. The above findings are of importance in the context of administering combined hepatitis A and B vaccine for which similar long-term data have been observed. All available data on monovalent and combined hepatitis A and hepatitis B vaccines indicates that there is no support for a hepatitis A or hepatitis B booster when a complete primary vaccination course is offered to immunocompetent individuals.

Long-term immunogenicity of hepatitis B vaccination in a cohort of Italian healthy adolescents

In 1992, 620 adolescents were vaccinated against hepatitis B. Anti-HBs concentrations were measured in 480 (77.4%) adolescents 1 month after completion of the primary course of vaccination. To assess the persistence of anti-HBs, 347 and 228 of such vaccinees were retested for anti-HBs in 1999 and for anti-HBs and anti-HBc in 2003. More than 10 years after vaccination, individuals with anti-HBs >or=10 mIU/ml were considered protected while those with antibody <10 mIU/ml were given a booster dose and retested 2 weeks later. Check performed in 2003 showed that 208/228 (91.2%) vaccinees retained protective concentrations of anti-HBs. All vaccinees were anti-HBc negative. 11 of the 12 (91.7%) individuals who were given a booster dose of vaccine showed a vigorous anamnestic response while the remaining one showed a weak response (10.6 mIU/ml). These data suggests that hepatitis B vaccination can confer long-term immunity and that immunological memory can outlast the loss of antibody. Hence, the use of routine booster doses of vaccine does not appear necessary to maintain long-term protection in successfully vaccinated immunocompetent individuals.

Antibody persistence and immune memory elicited by combined hepatitis A and B vaccination in older adults

Response to hepatitis A and B vaccines has been reported to decline with age. This open, prospective, single-site study examined the long-term response to the combined hepatitis A/B vaccine Twinrix in 98 primary responders aged 45-67 years. Levels of antibody against hepatitis A virus (HAV) and hepatitis B surface antigen (HBs) were tested 30 months after initial vaccination. At this stage, all participants remained seropositive for anti-HAV and 70% for anti-HBs. A booster vaccination was offered to those who had responded to the first vaccination but then lost protective levels of anti-HBs. An anamnestic response was observed in all cases.

Vaccines for preventing hepatitis B in health-care workers

BACKGROUND

Hepatitis B virus (HBV) causes acute and chronic liver diseases. Hepatitis B vaccination is recommended for health-care workers.

OBJECTIVES

To assess the beneficial and harmful effects of hepatitis B vaccination in health-care workers.

SEARCH STRATEGY

We searched the trial registers of The Cochrane Hepato-Biliary Group, The Cochrane Library, MEDLINE, and EMBASE to February 2003.

SELECTION CRITERIA

Randomised trials comparing any dose, injection route, injection site, or schedule of hepatitis B plasma-derived vaccines (PDV) or recombinant vaccines (RV) versus placebo, no intervention, or another hepatitis B vaccine in health-care workers.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted the data independently. The reviewers assessed the methodological quality of the trials regarding generation of the allocation sequence, allocation concealment, double blinding, and follow-up. The results were presented as relative risk (RR) with 95% confidence intervals (CI).

MAIN RESULTS

We identified 21 randomised trials, all with one or more methodological weaknesses. Four trials demonstrated that PDV versus placebo significantly decreased hepatitis B events at maximum follow-up (RR 0.51, 95% CI 0.35 to 0.73). RV did not differ significantly from PDV in eliciting a protective hepatitis B surface antibody (anti-HBs) level in two trials. Both vaccines were well tolerated. Low-dose vaccine (1 or 2 microg) by the intradermal route resulted in significantly more participants without protective anti-HBs level compared with high-dose (10 or 20 microg) by the intramuscular route (RR 1.41, 95% CI 1.13 to 1.76). The intradermal route caused significantly more local adverse events, while the intramuscular route caused significantly more systemic adverse events. The gluteal injection produced significantly more participants without protective anti-HBs level than the deltoid injection. The prevalence of anti-HBs seroconversion by rapid vaccination (0, 1, and 2 months) was significantly lower than that by standard vaccination (0, 1, and 6 months). Booster vaccinations with different RV doses (2.5, 5, 10, 20, or 40 microg) produced similar prevalence of anti-HBs seroconversion in three trials assessing participants who did not respond to previous HBV vaccination.

AUTHORS' CONCLUSIONS

PDV significantly prevents hepatitis B events. RV seems to be able to elicit similar protective anti-HBs levels. The intramuscular route with 20 microg RV was significantly more effective compared with the intradermal route with 2 microg RV as was the standard schedule compared with a rapid schedule and deltoid intramuscular injection compared with the gluteal intramuscular injection. It is unclear if booster vaccination of non-responders offers higher anti-HBs seroconversion and hepatitis B vaccine prevents the infection of hepatitis B mutants in health-care workers.

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).

A review of licensed viral vaccines, some of their safety concerns, and the advances in the development of investigational viral vaccines

Viral vaccines could be considered among the most important medical achievements of the 20th century. They have prevented much suffering and saved many lives. Although some curative antiviral drugs exist, we desperately depend on efforts by academic, governmental and industrial scientists in the advancement of viral vaccines in the prevention and control of infectious diseases. In the next decade, we hope to see advancement in the development of current and investigational viral vaccines against childhood and adult infections. In this article, we will review the licensed viral vaccines, some of their safety concerns, and the advances in the development of investigational viral vaccines.

Vaccines and immunotherapies for the prevention of infectious diseases having cutaneous manifestations

Although the development of antimicrobial drugs has advanced rapidly in the past several years, such agents act against only certain groups of microbes and are associated with increasing rates of resistance. These limitations of treatment force physicians to continue to rely on prevention, which is more effective and cost-effective than therapy. From the use of the smallpox vaccine by Jenner in the 1700s to the current concerns about biologic warfare, the technology for vaccine development has seen numerous advances. The currently available vaccines for viral illnesses include Dryvax for smallpox; the combination measles, mumps, and rubella vaccine; inactivated vaccine for hepatitis A; plasma-derived vaccine for hepatitis B; and the live attenuated Oka strain vaccine for varicella zoster. Vaccines available against bacterial illnesses include those for anthrax, Haemophilus influenzae, and Neisseria meningitidis. Currently in development for both prophylactic and therapeutic purposes are vaccines for HIV, herpes simplex virus, and human papillomavirus. Other vaccines being investigated for prevention are those for cytomegalovirus, respiratory syncytial virus, parainfluenza virus, hepatitis C, and dengue fever, among many others. Fungal and protozoan diseases are also subjects of vaccine research. Among immunoglobulins approved for prophylactic and therapeutic use are those against cytomegalovirus, hepatitis A and B, measles, rabies, and tetanus. With this progress, it is hoped that effective vaccines soon will be developed for many more infectious diseases with cutaneous manifestations.

Ten-year persistence of antibody to hepatitis B surface antigen in healthcare workers vaccinated against hepatitis B virus, and response to booster vaccination

This study estimated the number of HCWs with protective antibody levels 5 and 10 years after HBV vaccination. Kaplan-Meier probabilities of protective levels were 0.95 at 60 days after vaccination, 0.87 at 5 years, and 0.79 at 10 years. Those without protective levels displayed good response 7 and 30 days after a booster.

Long-term persistence of anti-HBs after vaccination against HBV: an 18 year experience in health care workers

The aim of the present study was to evaluate the long-term persistence of seroprotection after hepatitis B virus (HBV) vaccination. A total of 422 health care workers (HCWs) were evaluated 4.8-18.8 years after primary immunization (mean follow-up 11.8 years); 241 of them had received plasma-derived vaccines and 181 had been given yeast-derived vaccines; 107 subjects received a booster dose of yeast-derived vaccine 6 years after primary immunization with either plasma-derived or yeast-derived vaccines. Seroprotection was assumed when the anti-HBs titers were >10 mIU/ml. The overall response after primary immunization was 98.8%. Among subjects who reached a 10 year follow-up, those treated with plasma-derived vaccine had a seroprotection rate of 87.8 compared to 81.6% of those vaccinated with yeast-derived vaccines (P<0.001). Anti-HBs geometric mean titers (GMTs) after primary immunization were similar in the two groups, but were significantly lower at 10 years follow-up in the group that had received a yeast-derived vaccine (104 mIU/ml versus 244 mIU/ml in those who used a plasma-derived vaccine, P<0.05). Anti-HBs GMTs in the 107 subjects given the booster dose were 242 mIU/ml pre-booster titer, and rose to 35,171 mIU/ml after the booster dose. A mean 10.1 years after the booster dose, GMTs were 952 mIU/ml. Overall, the anti-HBs seroprotection rate was 95.4% (102 subjects). Based on GMT results, no booster dose is necessary in healthy adults for at least 10 years after primary immunization.

Analysis of anti-HBs levels in healthcare workers over 10 years following booster vaccination for hepatitis B virus

In this study, we analyzed anti-HBs levels in 104 Japanese healthcare workers who received three booster HBV surface antigen (HBsAg) vaccines because 80 became anti-HBs-negative at a mean of 2.4 years after the primary vaccination and 24 did not respond to primary vaccination. Of the re-vaccinees, 96% achieved a level of 10 mIU/ml or more of anti-HBs (i.e. seroprotected), 1 month after booster vaccination. Although anti-HBs levels of re-vaccinees decreased as rapidly as those of primary immunized vaccinees, at 10 years post-booster, 64% of re-vaccinees maintained anti-HBs levels at 10 mIU/ml or higher. Our results suggest that the additional three-dose protocol of booster HBsAg vaccination is beneficial in maintaining a seroprotective level of anti-HBs until new immunogenic vaccination protocols are established.

Long term antibody response to hepatitis B vaccination beginning at birth and to subsequent booster vaccination

BACKGROUND

Few studies have examined the long term persistence of antibody after hepatitis B immunization beginning at birth and the response to a subsequent challenge with a booster dose of vaccine.

METHODS

Two groups of children received hepatitis B vaccine on a schedule of birth and 1 and 6 months of age. Group 1 received recombinant vaccine and a booster dose at 5 years of age. Group 2 received plasma-derived vaccine and a booster dose at 9 years of age. Group 1 children were tested for antibody after the primary vaccine series. All children were tested for antibody before administration of the booster dose and at 2 and 4 weeks and 1 year after the booster. In addition all children were tested for markers of hepatitis B virus infection.

RESULTS

Antibody testing conducted after the primary series for children in Group 1 (n = 70) showed that 90% had protective antibody concentrations at 13 months of age, and testing before the booster dose showed that 41% had protective antibody concentrations. All children with protective antibody concentrations after the primary series had an anamnestic antibody response to the booster dose. In Group 2 (n = 41) 39% of children had protective antibody concentrations before the booster dose, and 93% had an anamnestic antibody response to the booster dose. One year after the booster dose there were 26-fold and 11-fold declines in antibody concentration in Groups 1 and 2, respectively.

CONCLUSIONS

A primary vaccination series with either plasma-derived or recombinant hepatitis B vaccine affords long term protection for children when vaccinated beginning soon after birth.

Development of antibody to hepatitis B surface antigen after liver transplantation for chronic hepatitis B

Patients with chronic hepatitis B virus (HBV) infection have a defective HBV-specific immune response, and the spontaneous development of antibody against hepatitis B surface antigen (anti-HBs) after liver transplantation has not been observed. We report the spontaneous production of anti-HBs in 21 of 50 (42%) patients receiving lamivudine monoprophylaxis after liver transplantation. Seroconversion to anti-HBs status (>10 mIU/mL) was found at a median of 8 days (range, 1 to 43 days) after transplantation. In each case, serial serum samples showed a >100% increase in antibody titer as compared with that of day 7 after transplantation in the absence of any blood product transfusion. The anti-HBs titer increased to a maximum within 3 months, and the peak titer was <100 mIU/mL in 10 patients, 100 to 1000 mIU/mL in 5 patients, and >1,000 mIU/mL in 6 patients. In 12 patients, anti-HBs disappeared from serum at a median of 201 days (range, 24 to 414 days), whereas the other 9 patients remained positive for anti-HBs at a median of 221 days (range, 94 to 1,025 days) after transplantation. Patients in whom anti-HBs in serum developed had a more rapid clearance of serum hepatitis B surface antigen (HBsAg) (log rank test, P =.011). Using logistic regression analysis, the only predictor of anti-HBs production was an HBV-immune donor (odds ratio, 18.9; 95% confidence interval, 3.2 to 112.4; P =.001). In conclusion, patients who undergo liver transplantation for chronic hepatitis B using lamivudine prophylaxis may develop anti-HBs spontaneously. The antibody is likely to be of donor origin, suggesting the possibility of adoptive immunity transfer through a liver graft.

Hepatitis B vaccine -- do we need boosters?

This review analyses the cumulated data from a number of long-term follow-up studies among infants, children and adults vaccinated against hepatitis B in industrialised and developing countries. Despite low or undetectable antibody responses years after vaccination, the development of HBsAg was a rarity and, if present, only transient. Some vaccinees developed anti-HBc responses but none developed an HB carrier state or clinical manifestations of disease. Studies demonstrating anamnestic responses among those with low or undetectable anti-HBs levels following challenge with HB vaccine, together with the production of anti-HBs in circulating B-cells by spot ELISA, confirmed the presence of immune memory among vaccinees. Anamnestic anti-HBs responses all correlate close in kinetics and magnitude with proliferative T-cell responses. The accumulated data from studies assessed in this Review indicate that protection is dependent on immune memory, rather than declining anti-HBs responses and add additional weight to the European Consensus recommendations (12) that following a complete course of vaccination, booster doses are unnecessary in immunocompetent persons. If implemented, this recommendation will have considerable cost benefits world-wide.

Some questions to be raised about the hepatitis B vaccine

The author consider some questions to be more carefully studied about the hepatitis B vaccine: route of injection (subcutaneous or intramuscular), amount of antigen (Ag), adjuvant (necessary or not), antigenic and molecular structure of HBsAg. What is important is to get high seroconversion rates, but not to get very high antibody titers (protective immunity is not dependent of antibody titers). Two types of vaccine could be used, and further studied. Why not use in healthy adults and children low dose vaccines (with 1.5-2.5 microg of HBsAg), possibly without adjuvant, and to be injected subcutaneously? And the 20 microg dose of vaccine could be used intramuscularly only for low- or non-responders, in high risk groups.

Stress, coping, and hepatitis B antibody status

OBJECTIVE

The present study investigated the association between exposure to stressful life events, coping style, and antibody status after hepatitis B vaccination.

METHODS

Two hundred sixty medical school undergraduates, who had received the three-dose hepatitis B vaccine before recruitment to this study, completed questionnaires measuring exposure to stressful life events during the past year, customary coping strategies, and health behaviors. Antibodies against hepatitis B surface antigen were determined; levels <100 mIU/ml were deemed inadequate.

RESULTS

Two participant cohorts were identified: those vaccinated within the last year and those vaccinated earlier. In the early vaccination cohort, participants with greater-than-average stress exposures had a more than two-fold increased risk of having an inadequate antibody titer. Coping by accepting the reality of stressful situations proved protective, whereas coping by substance use increased the risk of having an inadequate antibody count in this cohort. These associations remained significant after adjustment for possible mediators. Furthermore, the effects of stress and coping were largely independent of one another. Neither stress nor coping was significantly associated with antibody status in the recently vaccinated cohort.

CONCLUSIONS

The present study confirms that the immune system is sensitive to variations in psychological factors. Stressful life events and coping strategy seem to have a continuing impact on hepatitis B antibody status.

Variants of two major T cell epitopes within the hepatitis B surface antigen are not recognized by specific T helper cells of vaccinated individuals

Several naturally occurring variants of immunogenic T cell epitopes were identified within the hepatitis B surface antigen (HBsAg). The effect of these variants on the cellular immune response was studied in individuals vaccinated against HBV. Class-II restricted T-cell responses of 30 vaccinees were analyzed after stimulation of peripheral blood mononuclear cells (PBMCs) with 4 synthetic peptides representing the 4 T-cell epitopes of HBsAg known as of yet. The 2 epitopes P1 (aa 16-33) and P4 (aa 213-226) could be identified as the dominant ones in our vaccinees by proliferation assays and enzyme-linked immunospot assays. Responses to these epitopes were compared with responses to their naturally occurring variants found in HBV isolates of chronic virus carriers. Three of 11 variants of epitope P4 led to a complete loss of T-cell reactivity in 4 of 10 donors, all of whom reacted well to the corresponding wild-type sequence. The remaining 6 donors recognized these variants as well as the vaccine epitope. Similarly, 3 P1-variants of the 12 found induced only a significantly reduced reactivity in 4 of 10 donors, whereas they led to a normal response in the other 6 individuals. Stimulation of T cells also induced the secretion of antibody to HBsAg (anti-HBs) by specific B cells; however, those peptides that failed to activate T cells were also unable to cause any significant anti-HBs production. In conclusion, our results suggest an immune escape of certain mutant strains of HBV in vaccinated individuals could exist at the T-cell level.