Long-term persistence of antibodies induced by vaccination and safety follow-up, with the first combined vaccine against hepatitis A and B in children and adults

Post-treatment human papillomavirus antibody kinetics in cervical cancer patients

Antibodies to the E6 and E7 oncoproteins of high-risk human papillomavirus (HPV) types are strongly associated with HPV-driven cancer, while antibodies against the capsid protein L1 are considered cumulative exposure markers. To test the hypothesis that L1 antibody levels are stable over time, whereas E6 and E7 levels undergo decay after cervical cancer (CxCa) treatment, we performed multiplex serology for HPV16 and 18 antigens E6, E7 and L1 in a post-treatment study of 184 patients with invasive CxCa that were characterized with a median follow-up time of 725 days, and 2-12 sera per patient. Antibody titers significantly decreased within the first six months for HPV16 E6 and E7 but not L1, and stabilized for the following 12 months on a high level, with few patients showing seroreversion. Of 67 patients seropositive for HPV16 E6 at diagnosis, 28 (41.8%) showed a decrease in antibody titers of at least 50% within the first 18 months. Similarly, of 50 HPV16 E7 seropositives, 33 (66.0%) showed decreasing antibody levels, whereas antibody decay was less frequent for HPV16 L1 (12 of 47, 25.5%). Using a power-law mathematical model to characterize antibody decay kinetics, the mean (±s.e.) durations to a 50% reduction in antibody titers within individual patients were estimated to be 56.9 (±26.1) and 56.3 (±19.0) days for HPV16 E6 and E7, respectively. In summary, HPV16 E6 and E7 antibodies undergo a slow but significant decrease in antibody titers within the first 6-18 months following CxCa treatment. However, larger studies are needed to confirm the utility of serology for prediction of disease progression and time to relapse based on antibody decay kinetics. This article is part of the theme issue 'Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses'.

Quantification of plasma cell dynamics using mathematical modelling

Plasma cells (PCs) are the main antibody-producing cells in humans. They are long-lived so that specific antibodies against either pathogens or vaccines are produced for decades. PC longevity is attributed to specific areas within the bone marrow micro-environment, the so-called 'niche', providing the cells with required growth and survival factors. With antigen encounters, e.g. infection or vaccination, new PCs are generated and home to the bone marrow where they compete with resident PCs for the niche. We propose a parametrized mathematical model describing healthy PC dynamics in the bone marrow. The model accounts for competition for the niche between newly produced PCs owing to vaccination and resident PCs. Mathematical analysis and numerical simulations of the model allow explanation of the recovery of PC homoeostasis after a vaccine-induced perturbation, and the fraction of vaccine-specific PCs inside the niche. The model enables quantification of the niche-related dynamics of PCs, i.e. the duration of PC transition into the niche and the impact of different rates for PC transitions into and out of the niche on the observed cell dynamics. Ultimately, it provides a potential basis for further investigations in health and disease.

Persistence of antibodies 20 y after vaccination with a combined hepatitis A and B vaccine

Vaccination is the most effective and well-tolerated method of conferring long-term protection against hepatitis A and B viruses (HAV; HBV). Long-term studies are required to characterize the duration of protection and need for boosters. Following primary immunization of 150 and 157 healthy adults with 3-doses of combined hepatitis A/hepatitis B vaccine (HAB; Twinrix™, GSK Vaccines, Belgium) at 0-1-6 months in 2 separate studies, we measured vaccine-induced antibody persistence against HAV and HBV annually for 20 y (Study A: NCT01000324; Study B: NCT01037114). Subjects with circulating anti-HAV antibodies < 15 mIU/mL or with anti-hepatitis B surface antigen < 10 mIU/mL were offered an additional monovalent hepatitis A and/or B vaccine dose (Havrix™/Engerix™-B, GSK Vaccines, Belgium). Applying the immunogenicity results from these studies, mathematical modeling predicted long-term persistence. After 20 y, 18 and 25 subjects in studies A and B, respectively, comprised the long-term according-to-protocol cohort for immunogenicity; 100% and 96.0% retained anti-HAV antibodies ≥ 15 mIU/mL, respectively; 94.4% and 92.0% had anti-HBs antibodies ≥ 10 mIU/mL, respectively. Between Years 16–20, 4 subjects who received a challenge dose of monovalent hepatitis A vaccine (N = 2) or hepatitis B vaccine (N = 2), all mounted a strong anamnestic response suggestive of immune memory despite low antibody levels. Mathematical modeling predicts that 40 y after vaccination ≥ 97% vaccinees will maintain anti-HAV ≥ 15 mIU/mL and ≥ 50% vaccinees will retain anti-HBs ≥ 10 mIU/mL. Immunogenicity data confirm that primary immunization with 3-doses of HAB induces persisting anti-HAV and anti-HBs specific antibodies in most adults for up to 20 y; mathematical modeling predicts even longer-term protection.

Immunogenicity, effectiveness and safety of combined hepatitis A and B vaccine: a systematic literature review

BACKGROUND

Hepatitis A and B are two of the most common vaccine-preventable diseases and vaccination for Hepatitis A virus (HAV) and hepatitis B virus (HBV) is recommended for those at risk of contracting HAV and/or HBV through their occupation, travel or lifestyle.

OBJECTIVE

To describe the vaccine efficacy, immunogenicity, effectiveness and safety of the combined vaccine against hepatitis A and hepatitis B.

METHODS

A systematic review of the literature published between 1990 and 2015.

RESULTS

Anti-HAV seropositivity rates ranged from 96.2% to 100% and anti-HBs seroprotection rates from 82% to 100%. Antibodies persisted up to 15 years and geometric mean concentration (GMC) remained above the seropositivity cut-off value for both. Anti-HAV and anti-HBs immune responses were lower in less immunocompetent individuals one month after completion of the immunization schedule. The safety profiles of Twinrix(TM) and monovalent hepatitis A and B vaccines were similar.

CONCLUSION

The vaccine offers satisfactory long-term immunogenicity rates, expected duration of protection and safety profile similar to the monovalent hepatitis A or B vaccines.

Immunogenicity of quadrivalent HPV and combined hepatitis A and B vaccine when co-administered or administered one month apart to 9-10 year-old girls according to 0-6 month schedule

BACKGROUND

No immunogenicity data has been reported after a single dose of the quadrivalent HPV vaccine (qHPV-Gardasil®) and no data are available on co-administration of this vaccine with the HAV/HBV vaccine (Twinrix-Junior®). Two pre-licensure studies reported similar anti-HPV but lower anti-HBs titers when co-administering HPV and HBV vaccines.

OBJECTIVES

To assess the immunogenicity of the qHPV and HAV/HBV vaccine when co-administered (Group-Co-adm) or given one month apart (Group-Sep) and to measure the persistence of HPV antibodies three years post-second dose of qHPV vaccine in both study groups.

METHODS

416 9-10 year-old girls were enrolled. Vaccination schedule was 0-6 months. Anti-HAV and anti-HBs were measured in all subjects 6 months post-first dose and 1 month post-second dose. Anti-HPV were measured 6 months post-first dose in Group-Co-adm and in all subjects 1 and 36 months post-second dose.

RESULTS

Six months post-first dose: 100% of subjects had detectable anti-HAV and 56% and 73% had detectable anti-HBs in Group-Co-Adm and Group-Sep, respectively. In Group-Co-adm 94, 100, 99 and 96% had detectable antibodies to HPV 6, 11, 16 and 18, respectively. One month post-second dose of qHPV and HAV/HBV vaccine, in both study groups 99.5-100% of subjects had an anti-HAV titer ≥ 20IU/L, 97.5-97.6% an anti-HBs level ≥ 10IU/L, and 100% had an anti-HPV titer ≥ 3LU. Thirty-six months post-second dose of qHPV all but four subjects (99%) had antibodies to HPV18 and 100% had antibodies to HPV6, 11 and 16. The great majority (97-100%) had an anti-HPV titer ≥ 3 LU. Post-second dose administration of qHPV and HAV/HBV, no meaningful difference was observed in the immune response in the two study groups to any component of vaccines.

CONCLUSIONS

The results indicate that qHPV and HAV/HBV can be given during the same vaccination session. Two doses of of qHPV and HAV/HBV vaccines induce a strong immune response. Three years post-second dose of qHPV, the great majority of subjects had antibodies to HPV types included in the vaccine. A two-dose schedule for pre-adolescents might be a reasonable alternative to the currently approved three-dose schedules.

Long-term antibody persistence in children after vaccination with the pediatric formulation of an aluminum-free virosomal hepatitis A vaccine

BACKGROUND

The pediatric dose of the virosomal hepatitis A vaccine Epaxal, Epaxal Junior, is safe and immunogenic in children from 1 to 17 years of age. The present study investigated the long-term immunogenicity of Epaxal Junior. The standard doses of Epaxal and aluminum-adsorbed hepatitis A vaccine (Havrix Junior) were used as comparators.

METHODS

A total of 271 children who had completed a 0/6-month immunization schedule (priming and booster dose) participated in this follow-up study. Anti-hepatitis A virus (HAV) antibody levels were measured using a microparticle enzyme immunoassay (HAVAB 2.0 Quantitative; Abbott Diagnostics, Wiesbaden, Germany) starting at 18 months following the second dose, and then yearly until 66 months (ie, 5.5 years) after the second dose.

RESULTS

All subjects tested at Month 66 still had protective anti-HAV antibodies (≥10 mIU/mL). Antibody titers were generally lower in subjects 1-7 years old than in subjects 8-17 years old and higher in females 11-17 years old than in males 11-17 years old. In addition, an age-dependent decay was observed, that is, antibody decreased more rapidly in younger than in older children.

CONCLUSIONS

Vaccination of children with two doses of Epaxal Junior confers a real-time protection of at least 5.5 years. This protection is estimated to last approximately 25 years. Younger children showed lower antibody titers and a faster antibody decline than older children. Additional follow-up studies are needed beyond 5.5 years to further assess the long-term immunogenicity of Epaxal Junior.

Vaccine Adjuvant Systems containing monophosphoryl lipid A and QS-21 induce strong humoral and cellular immune responses against hepatitis B surface antigen which persist for at least 4 years after vaccination

BACKGROUND

Recombinant hepatitis B surface antigen (HBsAg) was used as a model antigen to evaluate persistence of cellular and humoral immune responses when formulated with three different Adjuvant Systems containing 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and QS-21, in an oil-in-water emulsion (AS02B and AS02V), or with liposomes (AS01B).

METHODS

This is an open, 4-year follow-up of a previous randomised, double-blind study. Healthy subjects aged 18-40 years received three vaccine doses on a month 0, 1, 10 schedule and were initially followed for 18 months. A total of 93 subjects (AS02B: n=30; AS02V: n=28; AS01B: n=35) were enrolled in this follow-up and had an additional blood sample taken at Year 4 (NCT02153320). The primary endpoint was the frequency of HBsAg-specific CD4(+) and CD8(+) T-cells expressing cytokines upon short-term in vitro stimulation of peripheral blood mononuclear cells with HBsAg-derived peptides. Secondary endpoints were anti-HBs antibody titres and frequency of HBsAg-specific memory B-cells.

RESULTS

A strong and persistent specific CD4(+) T-cell response was observed at Year 4 in all groups. HBsAg-specific CD4(+) T-cells expressed mainly CD40L and IL-2, and to a lesser extent TNF-α and IFN-γ. HBsAg-specific CD8(+) T-cells were not detected in any group. A high, persistent HBsAg-specific humoral immune response was observed in all groups, with all subjects seroprotected (antibody titre ≥10mIU/mL) at Year 4. The geometric mean antibody titre at Year 4 was above 100,000mIU/mL in all groups. A strong memory B-cell response was observed post-dose 2, which tended to increase post-dose 3 and persisted at Year 4 in all groups.

CONCLUSION

The MPL/QS-21/HBsAg vaccine formulations induced persistent immune responses up to 4 years after first vaccination. These Adjuvant Systems offer potential for combination with recombinant, synthetic or highly purified subunit vaccines, particularly for vaccination against challenging diseases, or in specific populations, although additional studies are needed.

New hepatitis B vaccine formulated with an improved adjuvant system

A new hepatitis B vaccine (FENDrix, GlaxoSmithKline Biologicals) containing as active substance 20 microg of recombinant hepatitis B virus surface antigen produced in Saccharomyces cerevisiae has recently been licensed in Europe. It is prepared with a novel adjuvant system: aluminum phosphate and 3-O-desacyl-4 -monophosphoryl lipid A. It is intended for use in adults from the age of 15 years onwards for active immunization against hepatitis B virus infection for patients with renal insufficiency (including prehemodialysis and hemodialysis patients). It is applied in a four-dose scheme: day 0, month 1, 2 and 6 after day 0. Due to the improved adjuvant system it induces higher antibody concentrations that reach protective levels in a faster fashion. Furthermore, due to higher titers reached after the primary immunization course, protective levels are retained for a longer period of time. Vaccination with FENDrix induces more transient local symptoms, with pain at the injection site being the most frequently reported solicited local symptom. Other symptoms such as fatigue, gastrointestinal disorders and headaches were also frequently observed but resolved without sequelae. The higher risk of hepatitis B transmission in patients with end-stage renal disease and the often immunocompromised status of these patients afford a tailored vaccination strategy that, up to now, has consisted of injecting double doses of ordinary hepatitis B vaccines. With the introduction of FENDrix there now exists an efficient alternative with superior immunogenicity that is, despite comparatively higher reactogenicity, well tolerated.

Response to hepatitis A and B vaccination after pediatric heart transplant

The determination of optimal immunization protocols for immunocompromised patients is important given limited data, the potential for decreased vaccine response, and the increased threat of infection. This retrospective study assessed the response to HA and/or HB vaccination in a cohort of 13 PHTx recipients. Descriptive statistics were applied to the data, and univariate analysis was utilized to identify possible factors associated with vaccine response. HA vaccination occurred in 12 (92%) patients of whom three (25%) became HA IgG positive post-vaccination. Eight (62%) patients had previously received HB vaccination. HB vaccination occurred in 10 (77%) patients of whom five (50%) were anti-HBS IgG positive post-vaccination. Median age at HA and HB vaccination was 10.0 yr, and median time post-PHTx was 8.2 yr. Looking at the entire patient cohort, a previous history of HB vaccination was associated with increased probability of HB vaccine success (7/8 [88%] vs. 1/5 [20%], p = 0.03). Vaccine response in this cohort of PHTx recipients was well below the rates of healthy children. Only a previous history of HB vaccination was significant for increased likelihood of vaccine response. Further study is needed to identify the optimal approach to vaccination for PHTx recipients.

Changes in seroprevalence to hepatitis A in Victoria, Australia: a comparison of three time points

Serological data provide an important measure of past exposure and immunity to hepatitis A virus (HAV) infection in a population. National serosurveys from developed countries have typically indicated a decline in HAV seroprevalence over time as sanitation levels improve. We examined trends in the seroepidemiology of HAV antibodies in Victoria, Australia, drawing on cross-sectional samples taken at three time points over a 20-year period. Stored sera from 1988 (n=753), 1998 (n=1091), and 2008 (n=791) from persons aged 1-69 years were obtained from the state of Victoria, Australia. The within-year population adjusted results show a significant trend of increasing population HAV seroprevalence over time from 34.3% (95% CI 31.7-36.9) in 1988, to 40.0% (95% CI 37.1-42.8) in 1998 and 55.1% (95% CI 52.1-58.1) in 2008, P<0.0001. A particularly noticeable rise in population seroprevalence was observed between 1998 and 2008 for those aged 5-39 years. The increase in HAV seropositivity over time is in contrast to the declining rates of disease notification in Australia. Based on comparisons with other Australian data, it appears the increase in population seroprevalence over the last two decades is unlikely to be due to endemic transmission of infection. Instead, other factors, including increases in travel to HAV endemic regions, migration to Australia from HAV endemic regions and vaccine uptake are more likely causes. Ongoing monitoring of serological HAV profiles in the population is required to determine future policy direction to prevent increased burden.

HIV-1 gp120 vaccine induces affinity maturation in both new and persistent antibody clonal lineages

Most antibodies that broadly neutralize HIV-1 are highly somatically mutated in antibody clonal lineages that persist over time. Here, we describe the analysis of human antibodies induced during an HIV-1 vaccine trial (GSK PRO HIV-002) that used the clade B envelope (Env) gp120 of clone W6.1D (gp120(W6.1D)). Using dual-color antigen-specific sorting, we isolated Env-specific human monoclonal antibodies (MAbs) and studied the clonal persistence of antibodies in the setting of HIV-1 Env vaccination. We found evidence of V(H) somatic mutation induced by the vaccine but only to a modest level (3.8% ± 0.5%; range 0 to 8.2%). Analysis of 34 HIV-1-reactive MAbs recovered over four immunizations revealed evidence of both sequential recruitment of naïve B cells and restimulation of previously recruited memory B cells. These recombinant antibodies recapitulated the anti-HIV-1 activity of participant serum including pseudovirus neutralization and antibody-dependent cell-mediated cytotoxicity (ADCC). One antibody (3491) demonstrated a change in specificity following somatic mutation with binding of the inferred unmutated ancestor to a linear C2 peptide while the mutated antibody reacted only with a conformational epitope in gp120 Env. Thus, gp120(W6.1D) was strongly immunogenic but over four immunizations induced levels of affinity maturation below that of broadly neutralizing MAbs. Improved vaccination strategies will be needed to drive persistent stimulation of antibody clonal lineages to induce affinity maturation that results in highly mutated HIV-1 Env-reactive antibodies.

Living on three time scales: the dynamics of plasma cell and antibody populations illustrated for hepatitis a virus

Understanding the mechanisms involved in long-term persistence of humoral immunity after natural infection or vaccination is challenging and crucial for further research in immunology, vaccine development as well as health policy. Long-lived plasma cells, which have recently been shown to reside in survival niches in the bone marrow, are instrumental in the process of immunity induction and persistence. We developed a mathematical model, assuming two antibody-secreting cell subpopulations (short- and long-lived plasma cells), to analyze the antibody kinetics after HAV-vaccination using data from two long-term follow-up studies. Model parameters were estimated through a hierarchical nonlinear mixed-effects model analysis. Long-term individual predictions were derived from the individual empirical parameters and were used to estimate the mean time to immunity waning. We show that three life spans are essential to explain the observed antibody kinetics: that of the antibodies (around one month), the short-lived plasma cells (several months) and the long-lived plasma cells (decades). Although our model is a simplified representation of the actual mechanisms that govern individual immune responses, the level of agreement between long-term individual predictions and observed kinetics is reassuringly close. The quantitative assessment of the time scales over which plasma cells and antibodies live and interact provides a basis for further quantitative research on immunology, with direct consequences for understanding the epidemiology of infectious diseases, and for timing serum sampling in clinical trials of vaccines.

Vaccination of travelers: how far have we come and where are we going?

Vaccine recommendations are a prominent part of health preparations before international travel. We review progress made in the past decade regarding vaccines used primarily by persons traveling from high-income countries to low- and middle-income countries. The combined hepatitis A-B vaccine, the recently licensed Vero cell-derived Japanese encephalitis vaccine and conjugated quadrivalent meningococcal vaccines are discussed. This article provides updates on yellow fever vaccine-associated visceral and neurologic adverse events, indications for influenza vaccine in travelers, the rapid immunization schedule for tick-borne encephalitis vaccine, schedules for postexposure rabies prophylaxis, and new insights about oral cholera vaccines following the outbreak in Haiti. The future should bring vaccines for serogroup B Neiserria meningitidis, dengue and malaria, as well as an inactivated yellow fever vaccine.

Randomized trial: immunogenicity and safety of coadministered human papillomavirus-16/18 AS04-adjuvanted vaccine and combined hepatitis A and B vaccine in girls

PURPOSE

This randomized, open, controlled, multicenter study (110886/NCT00578227) evaluated human papillomavirus (HPV)-16/18 AS04-adjuvanted vaccine (HPV-16/18 vaccine) coadministered with inactivated hepatitis A and B (HAB) vaccine. Coprimary objectives were to demonstrate noninferiority of hepatitis A, hepatitis B, and HPV-16/18 immune responses at month 7 when vaccines were coadministered, compared with the same vaccines administered alone.

METHODS

Healthy girls (9-15 years) were age-stratified (9, 10-12, and 13-15 years) and randomized to receive HPV (n = 270), HAB (n = 271), or HPV + HAB (n = 272). Vaccines were administered at months 0, 1, and 6. Immunogenicity was evaluated at months 0 and 7.

RESULTS

The hepatitis A immune response was noninferior for HPV + HAB, versus HAB, for seroconversion rates (100% in each group) and geometric mean antibody titers (GMTs) (95% CI) (4,504.2 [3,993.0-5,080.8] and 5,288.4 [4,713.3-5,933.7] mIU/mL, respectively). The hepatitis B immune response was noninferior for HPV + HAB, versus HAB, for anti-HBs seroprotection rates (98.3% and 100%); GMTs were 3,136.5 [2,436.0-4,038.4] and 5,646.5 [4,481.3-7,114.6] mIU/mL, respectively. The HPV-16/18 immune response was noninferior for HPV + HAB, versus HPV, for seroconversion rates (99.6% and 100% for both antigens) and GMTs (22,993.5 [20,093.4-26,312.0] and 26,981.9 [23,909.5-30,449.1] EL.U/mL for HPV-16; 8,671.2 [7,651.7-9,826.6] and 11,182.7 [9,924.8-12,600.1] EL.U/mL for HPV-18, respectively). No subject withdrew because of adverse events. No vaccine-related serious adverse events were reported. Immune responses and reactogenicity were similar in girls aged 9 years compared with the entire study population.

CONCLUSIONS

Results support coadministration of HPV-16/18 vaccine with HAB vaccine in girls aged 9-15 years. The HPV-16/18 vaccine was immunogenic and generally well tolerated in 9-year-old girls.

Antibody persistence and immune memory in adults, 15 years after a three-dose schedule of a combined hepatitis A and B vaccine

A combined hepatitis A and B vaccine is available since 1996. Two separate open-label primary studies evaluated the immunogenicity and safety of this hepatitis A and B vaccine (720 EI.U of HAV and 20 µg of HBsAg) in 306 healthy subjects aged 17-43 years who received three doses of the vaccine following a 0, 1, and 6 months schedule. These subjects were followed up annually for the next 15 years to evaluate long-term persistence of anti-HAV and anti-HBs antibodies. The subjects whose antibody concentrations fell below the cut-offs between Year 11 and Year 15 (anti-HAV: <15 mIU/ml; anti-HBs: <10 mIU/ml) were offered an additional dose of the appropriate monovalent hepatitis A and/or B vaccine. In subjects who received the additional vaccine dose, a blood sample was collected 1 month after vaccination. At the Year 15 time point, all subjects in Study A and Study B were seropositive for anti-HAV antibodies and 89.3% and 92.9% of subjects in the respective studies had anti-HBs antibody concentrations ≥10 mIU/ml. Four subjects (two in each study) received an additional dose of monovalent hepatitis B vaccine and mounted anamnestic responses to vaccination. No vaccine-related serious adverse events were reported. This study confirms the long-term immunogenicity of the three-dose regimen of the combined hepatitis A and B vaccine, as eliciting long-term persistence of antibodies and immune memory against hepatitis A and B for up to at least 15 years after a primary vaccination.

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

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

Evaluation of an inactivated Ross River virus vaccine in active and passive mouse immunization models and establishment of a correlate of protection

Ross River Virus has caused reported outbreaks of epidemic polyarthritis, a chronic debilitating disease associated with significant long-term morbidity in Australia and the Pacific region since the 1920s. To address this public health concern, a formalin- and UV-inactivated whole virus vaccine grown in animal protein-free cell culture was developed and tested in preclinical studies to evaluate immunogenicity and efficacy in animal models. After active immunizations, the vaccine dose-dependently induced antibodies and protected adult mice from viremia and interferon α/β receptor knock-out (IFN-α/βR(-/-)) mice from death and disease. In passive transfer studies, administration of human vaccinee sera followed by RRV challenge protected adult mice from viremia and young mice from development of arthritic signs similar to human RRV-induced disease. Based on the good correlation between antibody titers in human sera and protection of animals, a correlate of protection was defined. This is of particular importance for the evaluation of the vaccine because of the comparatively low annual incidence of RRV disease, which renders a classical efficacy trial impractical. Antibody-dependent enhancement of infection, did not occur in mice even at low to undetectable concentrations of vaccine-induced antibodies. Also, RRV vaccine-induced antibodies were partially cross-protective against infection with a related alphavirus, Chikungunya virus, and did not enhance infection. Based on these findings, the inactivated RRV vaccine is expected to be efficacious and protect humans from RRV disease.

Comparative immunogenicity of two vaccination schedules of a combined hepatitis A and B vaccine in healthy volunteers

In 1996, a combined vaccine against both hepatitis A and B was licensed and commercialized and has been recommended for healthcare personnel in Belgium. This study compares the immunogenicity against hepatitis B virus (HBV) and safety of two vaccination schedules (0-1-12 months and 0-1-6 months) with this vaccine. This is a randomized, stratified and controlled study in healthy adult workers, who are not occupationally exposed to HBV. Seroconversion (≥1 IU/L) and seroprotection (≥10 IU/L) rates were compared using Fisher's exact test; geometric mean concentrations (GMCs) of anti-HBs were compared using one-way ANOVA. All statistical analyses were carried out with SPSS 11 on Apple Macintosh. A total of 399 subjects were enrolled in the study, and 356 were analysed according to the protocol. The rate of ≥10 IU/L at 6 months was 70.6% in the group 0-1-12 and 79.9% in the group 0-1-6; this rate decreased to 55.9% at 12 months in the first group. Seroconversion and seroprotective rates against HBV measured at month 13 in group 0-1-12 (98.9% and 95.6%) and measured at month 7 in group 0-1-6 (99.4% and 97.1%) were not statistically significantly different. GMC of anti-HBs after the 0-1-12 schedule was more than two fold higher than after 0-1-6 schedule (P < 0.001). Reported side effects were comparable in both groups with a slight tendency to fewer side effects in the 0-1-12 group after the third dose. The results from our study show that the completed schedule 0-1-12 offers at least equal protective immunogenicity against HBV as the completed 0-1-6 schedule. People not receiving their third dose at 6 months can be given this dose up to 12 months after the first dose. The drawback of this flexibility, however, is the longer time period before the protection becomes effective.

Travelling with cystic fibrosis: recommendations for patients and care team members

There are no European Guidelines on issues specifically related to travel for people with cystic fibrosis (CF). The contributors to these recommendations included 30 members of the ECORN-CF project. The document is endorsed by the European Cystic Fibrosis Society and sponsored by the Executive Agency of Health and Consumers of the European Union and the Christiane Herzog Foundation. The main goal of this paper is to provide patient-oriented advice that complements medical aspects by offering practical suggestions for all aspects involved in planning and taking a trip. The report consists of three main sections, preparation for travel, important considerations during travel and at the destination, and issues specific to immunocompromised travellers. People with CF should be encouraged to consult with their CF centre prior to travel to another country. The CF centre can advise on the necessary preparation for travel, the need for vaccinations, essential medications that should be brought on the trip and also provide information relating to CF care in the region and plan of action in case of an emergency.

Combined hepatitis A and B vaccine: providing a bright future for preventing hepatitis

The first combined hepatitis A and B vaccine has been available in the United States since 2001. The vaccine provides protection against viral hepatitis with rapid seroprotection and lasting immunogenicity. This review outlines the product's components, clinical efficacy and opportunities for use in special circumstances. The vaccine has a good safety profile and has good tolerability. The combined hepatitis A and B vaccine is a well studied vaccine that provides rapid seroconversion with a good safety profile.

Hepatitis B vaccination strategies tailored to different endemicity levels: some considerations

Hepatitis B is a serious public health problem. Worldwide three different levels of hepatitis B endemicity (high, intermediate and low) can be distinguished. Areas with different levels of endemicity require tailored vaccination strategies to fit the needs for individuals at risk and/or countries, depending on the infection risk per age group, vaccination rate, duration of protection after vaccination, cost effectiveness of vaccination strategies and ease of implementation in the national immunization schedules.This opinion paper evaluates these factors and proposes a combination of infant risk group and universal adolescent vaccination for low endemic countries thus targeting the different groups at risk. A universal infant vaccination schedule starting with a newborn vaccination within 24h after birth is more appropriate in intermediate- and high-endemic regions.

Use of an accelerated immunization schedule for combined hepatitis A and B protection in the corporate traveler

Increased international business travel to moderate or high endemic areas of hepatitis A and B may leave many business travelers at risk for infection if not vaccinated. Many international business travelers depart for hepatitis A and B endemic areas within 2 months of the decision to travel. Many of these travelers do not seek pretravel medical advice and are unaware of the risks and modes of acquiring hepatitis A and B. Monovalent vaccines and a combined hepatitis A and B vaccine are available and can be administered on an accelerated schedule. Because many areas endemic for hepatitis A are also endemic for hepatitis B, accelerated administration of the combined vaccine can offer protection for many international business travelers destined for areas endemic for both diseases and should be part of corporate travel immunization programs.

Bivalent inactivated hepatitis A and recombinant hepatitis B vaccine

Hepatitis A and B remain serious global public health problems. Monovalent vaccines against hepatitis A and B have been available for many years. Since 1996, licenses have been gradually introduced for different formulations and immunization schedules of the first combined vaccines against both diseases. Twinrix Adult (with conventional and accelerated schedules) is available for the immunization of individuals aged 16 years or older in Europe and 18 years or older the USA. Twinrix Pediatric, with its three-dose schedule, and AmBirix, with its two-dose schedule, are licensed in Europe for ages 1-15 years. These vaccines offer a single injection for satisfactory protection against hepatitis A and B and an excellent safety and reactogenicity profile in comparison with monovalent vaccines. This article focuses on immunogenicity of the vaccines and proposes expert opinion and future directions in this field.

Long-term antibody persistence induced by a combined hepatitis A and B vaccine in children and adolescents

Two cohorts, comprising of subjects aged 1-6 years and 6-15 years were vaccinated with Twinrix according to a 0-, 1- and 6-month schedule. The 1-6 years cohort was followed up for 7.5 years and the 6-15 years cohort for 10 years. At the latest follow-up time point, all subjects were seropositive for anti-HAV antibodies, while 86.5% (32/37) and 95.5% (21/22) had anti-HBs >or= 10 mIU/ml in the 1-6 years and in the 6-15 years cohort. The geometric mean concentrations (GMCs; mIU/ml) were 233 and 680 for anti-HAV antibodies, and 147 and 165 for anti-HBs antibodies, in the 1-6 years and 6-15 years cohorts, respectively. The high persistence of circulating anti-HAV and anti-HBs antibodies in children and adolescents demonstrates the long-term protection offered by Twinrix in these age groups.

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.

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.

Ten-year antibody persistence induced by hepatitis A and B vaccine (Twinrix) in adults

BACKGROUND

Hepatitis A and B infections are prevalent worldwide and cause significant morbidity and mortality. A combined vaccine providing dual protection against hepatitis A and B is available (Twinrix, GlaxoSmithKline Biologicals).

METHOD

Two cohorts of adults aged 17-43 years were vaccinated with Twinrix according to a 0, 1, 6 months schedule and followed up for 10 years.

RESULTS

One month after the primary vaccination course (Month 7), all subjects were seropositive for anti-HAV and all had anti-HBs> or = 10 mIU/ml. At month 120, 100% of subjects (N=34; N=29) in both cohorts were seropositive for anti-HAV; 94.1% and 86.2% of subjects had anti-HBs > or = 10 mIU/ml. The geometric mean concentrations (GMC; mIU/ml) were 373.9 and 674.6 in the two cohorts for anti-HAV, and 103.8 and 320.0, respectively, for anti-HBs. None of the serious adverse events reported throughout the follow-up period were considered by the investigator to be causally related to vaccination.

CONCLUSIONS

Combined hepatitis A and B vaccine, Twinrix, is safe, well-tolerated and has demonstrated a highly immunogenic profile. Persistence of anti-HAV and anti-HBs antibodies in adults remains high for at least 10 years after primary vaccination.

Primary Hepatitis A vaccination failure is a rare although possible event: results of a retrospective study

A case of Hepatitis A occurred in a traveller in spite of a complete course of immunization with a combined HAV and HBV vaccine [Taliani G, Sbaragli S, Bartoloni A, Santini MG, Tozzi A, Paradisi F. Hepatitis A vaccine failure: how to treat the threat. Vaccine 2003;21(31):4505-6]. A retrospective study was performed to evaluate whether the failure was primary or could be attributed to a specific lot of vaccine or to its inadequate handling and/or storage. Two distinct populations of vaccinees were selected in a 1:2 proportion. The case group (N=31) included subjects who were vaccinated in the same period and with the same lot and batch of vaccine as the case. The control group (N=62) included subjects who received different lot and batch of the same vaccine as the case group. A persisting antibody response to HAV vaccine was found among all subjects (anti-HAV >20mIU/ml). The overall anti-HBs seropositivity rate (anti-HBs >10mIU/ml) was 74%, without significant difference between the case (77%) and the control group (73%; P>0.05). The reported Hepatitis A case can be attributed to a rare primary vaccine failure rather than to inefficacy of a specific lot of vaccine or to inappropriate vaccine handling or storage. Our study supports the indications for use of combined Hepatitis A+B immunization in travellers at risk for both infections, but stresses the need for information on correct hygienic behaviours while abroad.

Hepatitis A/B vaccination of adults over 40 years old: Comparison of three vaccine regimens and effect of influencing factors

Challenged by contrasting data on low immune responses in the elderly with a combined hepatitis A/B vaccine, a randomised, controlled study was conducted to assess the immunogenicity of three hepatitis A and B vaccination regimens (group 1: combined hepatitis A/B vaccine Twinrix [GSK]; group 2: co-administered hepatitis A vaccine, Havrix [GSK]+hepatitis B vaccine Engerix -B [GSK], group 3: co-administered hepatitis A vaccine, Vaqta [Sanofi-Pasteur MSD]+hepatitis B vaccine HB VAX PRO [Sanofi-Pasteur MSD]) and the effect of influencing factors in subjects >40 years. On completion of the full vaccination course, anti-HBs seroprotection (SP) rates were 92, 80 and 71% in groups 1, 2 and 3, respectively; anti-HAV seropositivity (S+) rates were 97, 99 and 99%, respectively. In group 1, anti-HBs SP rate was non-inferior as well as superior and anti-HAV S+ rate was non-inferior to that in groups 2 and 3. Anti-HBs response was most significantly influenced by the vaccine regimen, followed by age, gender and BMI (stepwise multiple regression analysis). BMI had the most significant influence on HAV response followed by age, gender and vaccine regimen. In conclusion, Twinrix induced superior hepatitis B SP rates and similar hepatitis A S+ rates compared to concomitant administration of monovalent vaccines in subjects aged >40 years.

Experience with hepatitis A and B vaccines

The lengthy history of efforts to understand the pathogenesis and means of preventing and controlling both hepatitis A and B is noteworthy for many exceptional scientific achievements. Among these are the development of vaccines to prevent the spread of infection through induction of active immunity to hepatitis A virus (HAV) and hepatitis B virus (HBV). The first plasma-derived hepatitis B vaccine was licensed in the United States in 1981 and was replaced by recombinant hepatitis B vaccines in 1986 and 1989. Vaccines to prevent HAV infection were licensed in the United States in 1995 and 1996. Subsequently, combination vaccines that included both hepatitis A and B vaccine components, or the hepatitis B component in combination with other commonly administered vaccines, were licensed in the United States. Despite significant reductions in hepatitis-related morbidity and mortality that have resulted from widespread use of these vaccines, vaccine-preventable morbidity and mortality still occur. The purposes of this article are to review clinical trial and other experience with hepatitis A and B vaccines in healthy individuals as well as in those with chronic liver disease, infected with the human immunodeficiency virus, or requiring hemodialysis; describe the impact that these vaccines and national recommendations for vaccination have had on reducing the incidence of HAV and HBV infection; and recommend expansion of these recommendations to include universal vaccination of adults as a means of further reducing the burden of viral hepatitis.

Hepatitis A and B Booster Recommendations: Implications for Travelers

Hepatitis A and B are serious vaccine-preventable diseases with a predominantly overlapping epidemiological distribution. Travelers, a term encompassing a range of individuals, are at risk of contracting these diseases if they are unvaccinated. Although the benefits of the primary vaccination course of hepatitis A and B vaccines are clear, the administration of hepatitis A and B boosters varies worldwide. Recommendations on the need for booster vaccinations have recently been published, and the implications of these recommendations for travelers are discussed in this review. Until a greater understanding is reached on the immunogenicity of hepatitis A and B vaccines in certain special groups (e.g., immunocompromised persons), there will be a need to monitor antibody levels to assess whether booster vaccinations are required. However, for the majority of immunocompetent travelers, the full primary vaccination course will provide protection from both hepatitis A and B infection in the long term, without the need for boosters.

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.

Immunisation in the current management of cystic fibrosis patients

Although no special recommendations exist, clearly patients with cystic fibrosis (CF) can benefit from immunisation. We reviewed the literature regarding vaccination in CF and other chronic diseases. CF subjects should follow national immunisation programmes without delay to obtain optimal vaccination coverage. Indeed they may escape normal programmes due to frequent hospital admissions and school absenteeism and may be more at risk to get "vaccine-controlled" diseases at any age. There is no uniform European immunisation schedule for basic infant and childhood vaccines or for vaccines against hepatitis A (HAV) and B (HBV), varicella (VZ) and booster vaccinations. HAV and HBV vaccination is appropriate in CF as recommended in general for patients with chronic liver disease (CLD). Varicella (VZ) vaccination is not recommended in all European countries. There are no recent data about possible worsening of pulmonary status following VZ in CF, but it is known to cause pulmonary damage in non-CF adults and to be potentially fatal post transplantation and during steroid treatment. Therefore it is recommended at least for seronegative adolescents and transplant candidates. Influenza vaccine is recommended annually for CF patients aged > or =6 months. Pneumococcal vaccine is generally indicated for CF patients. RSV infection might play a role in the initial Pseudomonas colonization and the decline in pulmonary function. However no RSV vaccine is available at present. There are no recommendations for palivizumab in CF as an alternative but expensive prophylaxis. Anti-bacterial vaccinations protecting directly against Pseudomonas aeruginosa colonisation are promising for the future, potential candidates are currently being assessed in phase III clinical trials. More studies are needed to complete recommendations especially for CF adults and transplant candidates.

A two-dose schedule for combined hepatitis A and B vaccination in children aged 6–15years

A combined hepatitis A and B vaccine, Twinrix, in a paediatric formulation for ages 1-15 years and in an adult formulation for those ages 16 years and older, became commercially available in Turkey as well as in many countries. It is administered according to a three-dose schedule (0, 1 and 6 months). A reduction in the number of doses would improve the compliance rate and reduce administration costs. Therefore, we planned a trial evaluation of the immunogenicity, safety and reactogenicity profile of a high-dose combined hepatitis A and B vaccine, administered in two doses, compared with the profile of a paediatric-dose combined vaccine, administered in three doses, in healthy children aged 6-15 years. One hundred children were randomly attributed to the two study groups. The first group (paediatric-dose vaccine group) received the licensed Twinrix Paediatric, at months 0, 1 and 6; the second group (high-dose vaccine group) received the high-dose vaccine, following a 0, 6 months schedule. The reactogenicity was assessed after each vaccine dose. The immunogenicity was evaluated by testing for anti-HBs and anti-HAV antibodies. Seroconversion rates and geometric mean titres (GMTs) were compared. Both formulations of the combined vaccine were well tolerated. The high-dose combined vaccine administered in two doses, elicits satisfactory immunogenicity profiles, similar to those elicited by the paediatric vaccine administered in three doses. On completion of the vaccination schedule in the two groups all children were protected against hepatitis B and immune for hepatitis A. Anti-HAV GMTs after completion of the vaccination schedule were 7163 mlU/ml in the paediatric-dose group, 8241 mlU/ml in the high-dose group; anti-HBs GMTs were 8679 and 4583 mlU/ml, respectively. These results indicate that a two-dose schedule, compared with the standard three-dose schedule, offers fewer injections for satisfactory protection against the two infections. This means fewer clinic visits, lower administration costs, better compliance, and higher coverage rate. Therefore, this two-dose schedule can be considered an appropriate regimen for the immunization of children and adolescents against hepatitis A and B infection, in the context of school-based immunization programmes.

Vaccination options for last-minute travellers in need of travel-related prophylaxis against hepatitis A and B and typhoid fever: a practical guide

Last-minute travellers represent a particular challenge to travel healthcare professionals, as standard vaccination schedules can take a few months to complete. This has led researchers to investigate the value of alternative accelerated schedules and existing schedules among this group, particularly with respect to time taken for an individual to seroconvert, duration of protection and multiple vaccination requirements. This paper reviews the available options for the three most common vaccine preventable diseases among travellers-hepatitis A, hepatitis B and typhoid fever. Studies suggest that even if the first dose of hepatitis A vaccine is given on the day of travel, this will provide adequate protection, and that immunity to typhoid fever can be provided in over 70% of travellers following vaccination 1 week prior to departure. For hepatitis B, an accelerated schedule of 0, 7 and 21-days has been shown to induce early protection, and is considered to be of benefit to the last-minute traveller. Practical guidelines on vaccination options from one week up to one month, as well as one month or more prior to travel are presented. This should provide guidance for travel healthcare professionals, and reassure last-minute travellers that they need not begin their journey unprotected against these three serious infectious diseases.

Hepatitis A booster vaccination: is there a need?

Hepatitis A is one of the most common vaccine-preventable infectious diseases in the world. Effective vaccines against hepatitis A have been available since 1992, and they provide long-term immunity against the infection. However, there is no worldwide consensus on how long protection will last or whether there will be a need for hepatitis A virus (HAV) booster vaccinations in the future. In most countries, booster-vaccination policy is guided by manufacturers' recommendations, national authorities, or both. In June, 2002, a panel of international experts met to review the long-term immunogenicity and protection conferred by HAV vaccine in different population groups. Data have shown that after a full primary vaccination course, protective antibody amounts persist beyond 10 years in healthy individuals, and underlying immune memory provides protection far beyond the duration of anti-HAV antibodies. The group concluded that there is no evidence to lend support to HAV booster vaccination after a full primary vaccination course in a healthy individual. However, further investigations are needed before deciding if boosters can be omitted in special patient-groups.

Immunogenicity of combined hepatitis A and B vaccine in elderly persons

More and more elderly people travel to areas where hepatitis A and B are endemic. Their immune system is less effective than in young persons. Therefore, it has to be insured that these travelers have protective immunity after vaccination. In a retrospective study we measured anti hepatitis virus (anti-HAV) and anti-HBs in elderly persons (N = 104, mean age 54 years) after combined hepatitis A/B vaccination under every-day conditions. After complete vaccination only 36 (34.6%) had antibodies against both viruses. Only 23 (29%) of 80 vaccinees older than 40 years were protected against hepatitis B and 52 (65%) against hepatitis A. The response to the vaccination decreased with increasing age. Vaccination against hepatitis B-but not against hepatitis A-was also influenced by the presence of chronic disease. After one booster 87% of the anti-HAV negative vaccinees developed protective anti-HAV antibodies. Anti-HBs can be expected in about 50% of the HBV negative vaccinees with every single booster. These results indicate that combined hepatitis A/B vaccination is not very effective in elderly persons. After complete vaccination their anti-HAV and anti-HBs antibodies have to be controlled to insure protection. In case of vaccination-failure boosters are very effective.

Prevention of hepatitis A by vaccination

Inactivated hepatitis A vaccines have been available for more than a decade. Characteristics of the vaccines, comparative data among different formulations and the possibility of combination and association with other vaccines are reviewed in this article. Hepatitis A vaccines show high immunogenicity with different schedules and associations, induce long-term protection irrespective of timing of booster dose, and present an excellent safety profile. Pre-exposure efficacy has been demonstrated in large trials and postexposure protection has been described in family contacts of acute cases. The recommendations for the use of hepatitis A vaccines for immunisation campaigns and for targeted groups, such as travellers and people at risk for occupational and iatrogenic exposure or lifestyle behaviours, are discussed. Aspects related to economic analysis of vaccination strategies are also considered.