Immunogenicity and reactogenicity of the combined hepatitis A and B vaccine in young adults

Response to hepatitis B virus vaccination in individuals with chronic hepatitis C virus infection

BACKGROUND

Previous reports show conflicting results regarding hepatitis B virus (HBV) vaccine efficacy in Hepatitis C virus (HCV)-infected individuals.

AIMS

To evaluate HBV-vaccine response and identify possible factors that may contribute to lower vaccine efficacy in patients infected with HCV.

METHODS

We retrospectively evaluated all patients with chronic HCV infection at Hennepin County Medical Center, in Minneapolis, Minnesota, between 2002 and 2018. We addressed laboratory, liver-related, virus-related as well as vaccine-related variables, and their association to HBV vaccine response. Differences were tested using either a Chi-squared test or a T test to compare means between the two populations. Multivariate regression was modeled as a logistic regression.

RESULTS

1506 patients were evaluated, of which 525 received appropriate HBV vaccination and were assessed for response. Among those, 79% were vaccine responders and 21% were non-responders. On multivariate analysis, cirrhosis was associated with lower response to the vaccine (OR 0.6, CI 0.44-0.94). We found no significant differences for vaccine response in relation to smoking (87% vs 86%), IV drug abuse (74% vs 72%), Diabetes Mellitus (26% vs 22%) being on hemodialysis (2% vs.5%), or virus related variables.

CONCLUSION

HCV infection seems to impair HBV vaccine response, with cirrhosis being the only identifiable risk factor for hypo-responsiveness among studied clinical and virus-related variables.

Hepatitis A immunisation in persons not previously exposed to hepatitis A

This review is withdrawn because it is outdated. A new review is to be published by the end of 2019.

Hepatitis B Vaccination Induced TNF-α- and IL-2-Producing T Cell Responses in HIV- Healthy Individuals Higher than in HIV+ Individuals Who Received the Same Vaccination Regimen

We investigated cytokine production and expression of degranulation marker CD107a after different strategies of hepatitis B virus (HBV) vaccination in human immunodeficiency virus-infected individuals, which were three doses of 20 μg (standard dose group), four doses of 20 μg (four doses group), or four doses of 40 μg (four double doses group), compared to standard dose vaccination in healthy controls. PBMCs collected at different time points were stimulated in vitro with recombinant hepatitis B surface antigen and analyzed by flow cytometry. There was an increase in TNF-α production of total and memory CD4+ T cells at 7 months after vaccination in healthy controls compared to the HIV+ group, which received the same standard vaccination regimen. An increase in the IL-2-producing memory CD4+ T cells in the healthy control group was also observed at 7 months after vaccination. No differences were observed between the healthy controls and both groups of four doses at any time point of study. These results suggest that the standard HBV vaccination schedule might induce better production of TNF-α and IL-2 from CD4+ T cells in healthy individuals. Modification of HBV vaccination schedule by increasing the frequency and/or dosage may improve the CMI response in HIV-infected individuals. This trial is registered with NCT1289106.

Characterization of an age-response relationship to GSK's recombinant hepatitis B vaccine in healthy adults: An integrated analysis

The immune system becomes less effective with age, and older age is associated with an increased susceptibility to diseases and reduced responses to vaccination. Furthermore, some adult populations, such as those with diabetes mellitus, are at increased risk of acute hepatitis B virus (HBV) infection. Decreasing responses to vaccination with advanced age have been described, but it is not known at what age immunogenicity starts to reduce, or until what age immunogenicity remains acceptable (for example ≥80 % seroprotection post-vaccination). We characterized the relationship between age and seroprotection rate induced by recombinant HBV vaccination by conducting a pooled analysis of clinical trial data. Healthy adults aged ≥20 y who had been vaccinated with 20μg HBV vaccine (Engerix™ B, GSK Vaccines, Belgium) in a 0, 1, 6 months schedule in 11 studies since 1996 were included. The observed seroprotection rate, defined as an anti-HBV surface antigen antibody concentration ≥10 mIU/ml was 94.5% in the whole population (N = 2,620, Total vaccinated cohort), ranging from 98.6% in adults vaccinated at age 20–24 years, to 64.8% in those vaccinated at age ≥65 y A model on seroprotection rates showed a statistically significant decrease with age, and predicted that the anti-HBs seroprotection rate remains ≥90% up to 49 y of age and ≥80% up to 60 y of age. Individuals at risk of HBV infection should be vaccinated as early in life as possible to improve the likelihood of achieving seroprotection. Additional studies are needed to identify whether unvaccinated individuals older than 60 y would benefit from regimens that include additional or higher vaccine doses.

Association between hepatitis B vaccine antibody response and CD4 reconstitution after initiation of combination antiretroviral therapy in HIV-infected persons

Background

Hepatitis B virus (HBV) vaccine antibody response has been associated with reduced risk of AIDS or death. However, it is unknown whether HBV vaccine responsiveness is associated with improved immune reconstitution during treatment with combination antiretroviral therapy (cART). We evaluated the relationship between HBV vaccine response status and CD4 reconstitution on cART in the U.S Military HIV Natural History Study.

Methods

Participants with viral load <400 copies/mL within 1 year on initial cART and documented HBV vaccination and surface antibody (anti-HBs) prior to cART were included. Participants were characterized as HBV vaccine responders (anti-HBs ≥10 IU/L) or non-responders (<10 IU/L) and further divided into 2 groups based on vaccine administration before or after HIV diagnosis. Linear mixed regression was used to model CD4 reconstitution during the first year of cART.

Results

Of the 307 and 169 participants vaccinated before or after HIV diagnosis, HBV vaccine response occurred in 288 (94%) and 74 (44%), respectively. For those vaccinated before HIV diagnosis, CD4 counts increased by a median 190 [IQR 99–310] cells/mm³ for responders and 186 [IQR 116–366] cells/mm³ for non-responders during the first year (P = 0.684). Participants vaccinated after HIV diagnosis had median increases of 185 [IQR 76–270] and 143 [IQR 47–238] cells/mm³ for responders and non-responders, respectively (P = 0.134). In contrast to those with CD4 > 350 cells/mm³ at cART initiation, participants with CD4 < 200 and 200–350 cells/mm³ had significantly reduced CD4 gains in both groups by longitudinal mixed models, but there was no difference in CD4 recovery according to HBV vaccine seroresponse.

Conclusions

Although HBV vaccine responsiveness is associated with a reduction in HIV disease progression, HBV vaccine responders do not achieve greater CD4 gains during the first year of cART. Additional clinical markers are needed to predict the magnitude of post-cART immune recovery.

Hepatitis B vaccine responsiveness and clinical outcomes in HIV controllers

Background

Hepatitis B virus (HBV) vaccine responsiveness is associated with reduced risk of AIDS or death in HIV-infected individuals. Although HIV controllers (HIC) typically have favorable immunologic and clinical characteristics compared to non-controllers, vaccine responsiveness has not been studied.

Methods and Findings

In the U.S. Military HIV Natural History Study, HBV vaccine response was defined as antibody to hepatitis B surface antigen (anti-HBs) ≥10 IU/L after last vaccination. For determination of vaccine responsiveness, HIC (n = 44) and treatment-naïve non-controllers (n = 476) were not on highly active antiretroviral therapy (HAART) when vaccinated while treated non-controllers (n = 284) received all HBV vaccine doses during viral load (VL)-suppressive HAART. Progression to AIDS or death was also compared for all HIC (n = 143) and non-controllers (n = 1566) with documented anti-HBs regardless of the timing of HBV vaccination. Positive vaccine responses were more common in HIC (65.9%) compared to HAART-naïve non-controllers (36.6%; P<0.001), but similar to non-controllers on HAART (59.9%; P = 0.549). Factors associated with vaccine response for HIC compared to HAART-naïve non-controllers include HIC status (OR 2.65, 95% CI 1.23–5.89; P = 0.014), CD4 count at last vaccination (OR 1.28, 1.15–1.45 for every 100 cells/uL; P<0.001), and number of vaccine doses administered (OR 0.56, 0.35–0.88; P = 0.011). When HIC were compared to non-controllers on HAART, only CD4 count at last vaccination was significant (OR 1.23, 1.1–1.38 for every 100 cells/uL; P<0.001). The rate of AIDS or death per 100 person/years for HIC compared to non-controllers was 0.14 (95% CI 0–0.76) versus 0.98 (95% CI 0.74–1.28) for vaccine responders and 0 (95% CI 0–2.22) versus 4.11 (95% CI 3.38–4.96) for non-responders, respectively.

Conclusions

HIC have improved HBV vaccine responsiveness compared to treatment-naïve non-controllers, but similar to those on VL-suppressive HAART. Progression to AIDS or death can be predicted by HBV vaccine responder status for non-controllers, however these events are rarely observed in HIC.

Immune exhaustion and immune senescence: two distinct pathways for HBV vaccine failure during HCV and/or HIV infection

Given the shared risk factors for transmission, co-infection of hepatitis B virus (HBV) with hepatitis C virus (HCV) and/or human immunodeficiency virus (HIV) is quite common, and may lead to increases in morbidity and mortality. As such, HBV vaccine is recommended as the primary means to prevent HBV super-infection in HCV- and/or HIV-infected individuals. However, vaccine response (sero-conversion with a hepatitis B surface antibody titer >10 IU/L) in this setting is often blunted, with poor response rates to standard HBV vaccinations in virally infected individuals when compared with the healthy subjects. This phenomenon also occurs to other vaccines in adults, such as pneumococcal and influenza vaccines, in other immunocompromised hosts who are really at risk for opportunistic infections, such as individuals with hemodialysis, transplant, and malignancy. In this review, we summarize the underlying mechanisms involving vaccine failure in these conditions, focusing on immune exhaustion and immune senescence--two distinct signaling pathways regulating cell function and fate. We raise the possibility that blocking these negative signaling pathways might improve success rates of immunizations in the setting of chronic viral infection.

Tim-3 alters the balance of IL-12/IL-23 and drives TH17 cells: role in hepatitis B vaccine failure during hepatitis C infection

Hepatitis B virus (HBV) vaccination is recommended for individuals with hepatitis C virus (HCV) infection given their shared risk factors and increased liver-related morbidity and mortality upon super-infection. Vaccine responses in this setting are often blunted, with poor response rates to HBV vaccinations in chronically HCV-infected individuals compared to healthy subjects. In this study, we investigated the role of T cell immunoglobulin mucin domain-3 (Tim-3)-mediated immune regulation in HBV vaccine responses during HCV infection. We found that Tim-3, a marker for T cell exhaustion, was over-expressed on monocytes, leading to a differential regulation of IL-12/IL-23 production which in turn TH17 cell accumulation, in HCV-infected HBV vaccine non-responders compared to HCV-infected HBV vaccine responders or healthy subjects (HS). Importantly, ex vivo blockade of Tim-3 signaling corrected the imbalance of IL-12/IL-23 as well as the IL-17 bias observed in HBV vaccine non-responders during HCV infection. These results suggest that Tim-3-mediated dysregulation of innate to adaptive immune responses is involved in HBV vaccine failure in individuals with chronic HCV infection, raising the possibility that blocking this negative signaling pathway might improve the success rate of HBV immunization in the setting of chronic viral infection.

The effects of booster vaccination on combined hepatitis A and hepatitis B vaccine in both anti-HBs and anti-HAV negative children 5-15 years after hepatitis B vaccine primary immunization

In the present study, we investigated the changes in both anti-HAV lgG and anti-HBs lgG levels and compared the antibody seroconversion rates of different doses of combined hepatitis A and hepatitis B vaccine in children. Children who were vaccinated as infants with Hepatitis B vaccine were revaccinated at 5-15 y of age, then the antibody titers were monitored. Among 283 children, this study found that the anti-HAV seroconversion rates (defined as anti-HAV ≥ 1 mIU/ml) after the first and the third dose were 79.9% and 100% respectively; these observed differences were statistically significant (P<0.05); the corresponding geometric mean titers (GMTs) were 4.72 ± 2.63 mIU/ml and 13.46 ± 1.16 mIU/ml respectively. The anti-HBs seroconversion rates (defined as an anti-HBs ≥ 10 mIU/ml) were 82.3% and 99.0% respectively; these observed differences were statistically significant (P<0.05); and the corresponding titers were 319.95 ± 5.16 mIU/ml and 418.59 ± 3.89 mIU/ml respectively. After the first booster dose, the difference in anti-HAV seroconversion rate was statistically significant in children aged 5-9 y and 10-15 y (P<0.05), as was the difference of anti-HBs seroconversion, whereas after the third dose the difference was not statistically significant (P>0.05). This study demonstrated that the immunization effects of booster vaccination with combined hepatitis A and hepatitis B vaccine is successful for children. A single booster dose is adequate for younger children, while three doses are needed for older children.

Hepatitis A immunisation in persons not previously exposed to hepatitis A

BACKGROUND

In many parts of the world, hepatitis A infection represents a significant cause of morbidity and socio-economic loss. Whilst hepatitis A vaccines have the potential to prevent disease, the degree of protection afforded against clinical outcomes and within different populations remains uncertain. There are two types of hepatitis A virus (HAV) vaccine, inactivated and live attenuated. It is important to determine the efficacy and safety for both vaccine types.

OBJECTIVES

To determine the clinical protective efficacy, sero-protective efficacy, and safety and harms of hepatitis A vaccination in persons not previously exposed to hepatitis A.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and China National Knowledge Infrastructure (CNKI) up to November 2011.

SELECTION CRITERIA

Randomised clinical trials comparing HAV vaccine with placebo, no intervention, or appropriate control vaccines in participants of all ages.

DATA COLLECTION AND ANALYSIS

Data extraction and risk of bias assessment were undertaken by two authors and verified by a third author. Where required, authors contacted investigators to obtain missing data. The primary outcome was the occurrence of clinically apparent hepatitis A (infectious hepatitis). The secondary outcomes were lack of sero-protective anti-HAV immunoglobulin G (IgG), and number and types of adverse events. Results were presented as relative risks (RR) with 95% confidence intervals (CI). Dichotomous outcomes were reported as risk ratio (RR) with 95% confidence interval (CI), using intention-to-treat analysis. We conducted assessment of risk of bias to evaluate the risk of systematic errors (bias) and trial sequential analyses to estimate the risk of random errors (the play of chance).

MAIN RESULTS

We included a total of 11 clinical studies, of which only three were considered to have low risk of bias; two were quasi-randomised studies in which we only addressed harms. Nine randomised trials with 732,380 participants addressed the primary outcome of clinically confirmed hepatitis A. Of these, four trials assessed the inactivated hepatitis A vaccine (41,690 participants) and five trials assessed the live attenuated hepatitis A vaccine (690,690 participants). In the three randomised trials with low risk of bias (all assessing inactivated vaccine), clinically apparent hepatitis A occurred in 9/20,684 (0.04%) versus 92/20,746 (0.44%) participants in the HAV vaccine and control groups respectively (RR 0.09, 95% CI 0.03 to 0.30). In all nine randomised trials, clinically apparent hepatitis A occurred in 31/375,726 (0.01%) versus 505/356,654 (0.18%) participants in the HAV vaccine and control groups respectively (RR 0.09, 95% CI 0.05 to 0.17). These results were supported by trial sequential analyses. Subgroup analyses confirmed the clinical effectiveness of both inactivated hepatitis A vaccines (RR 0.09, 95% CI 0.03 to 0.30) and live attenuated hepatitis A vaccines (RR 0.07, 95% CI 0.03 to 0.17) on clinically confirmed hepatitis A. Inactivated hepatitis A vaccines had a significant effect on reducing the lack of sero-protection (less than 20 mIU/L) (RR 0.01, 95% CI 0.00 to 0.03). No trial reported on a sero-protective threshold less than 10 mIU/L. The risk of both non-serious local and systemic adverse events was comparable to placebo for the inactivated HAV vaccines. There were insufficient data to draw conclusions on adverse events for the live attenuated HAV vaccine.

AUTHORS' CONCLUSIONS

Hepatitis A vaccines are effective for pre-exposure prophylaxis of hepatitis A in susceptible individuals. This review demonstrated significant protection for at least two years with the inactivated HAV vaccine and at least five years with the live attenuated HAV vaccine. There was evidence to support the safety of the inactivated hepatitis A vaccine. More high quality evidence is required to determine the safety of live attenuated vaccines.

Impaired hepatitis B vaccine responses during chronic hepatitis C infection: involvement of the PD-1 pathway in regulating CD4(+) T cell responses

Vaccination for hepatitis B virus (HBV) in the setting of hepatitis C virus (HCV) infection is recommended, but responses to vaccination are blunted when compared to uninfected populations. The mechanism for this failure of immune response in HCV-infected subjects remains unknown but is thought to be a result of lymphocyte dysfunction during chronic viral infection. We have recently demonstrated that PD-1, a novel negative immunomodulator for T cell receptor (TCR) signaling, is involved in T and B lymphocyte dysregulation during chronic HCV infection. In this report, we further investigated the role of the PD-1 pathway in regulation of CD4(+) T cell responses to HBV vaccination in HCV-infected individuals. In a prospective HCV infected cohort, a poor response rate to HBV vaccination as assayed by seroconversion was observed in HCV-infected subjects (53%), while a high response rate was observed in healthy or spontaneously HCV-resolved individuals (94%). CD4(+) T cell responses to ex vivo stimulations of anti-CD3/CD28 antibodies or hepatitis B surface antigen (HBsAg) were found to be lower in HBV vaccine non-responders compared to those responders in HCV-infected individuals who had received a series of HBV immunizations. PD-1 expression on CD4(+) T cells was detected at relatively higher levels in these HBV vaccine non-responders than those who responded, and this was inversely associated with the cell activation status. Importantly, blocking the PD-1 pathway improved T cell activation and proliferation in response to ex vivo HBsAg or anti-CD3/CD28 stimulation in HBV vaccine non-responders. These results suggest that PD-1 signaling may be involved in impairing CD4(+) T cell responses to HBV vaccination in subjects with HCV infection, and raise the possibility that blocking this negative signaling pathway might improve success rates of immunization in the setting of chronic viral infection.

Response to hepatitis A and B vaccine alone or in combination in patients with chronic hepatitis C virus and advanced fibrosis

Patients with advanced fibrosis are at increased risk of severe outcomes if they develop acute infection with hepatitis A (HAV) or hepatitis B (HBV) viruses. There are no data on the efficacy of combined HAV/HBV vaccination in patients with advanced fibrosis. Our aim was to evaluate the response to the HAV and HBV vaccine alone or in combination for patients with chronic hepatitis C (HCV) and advanced fibrosis and to evaluate the impact of administering the vaccine while patients were receiving peginterferon for treatment of chronic HCV. In this prospective study of patients with advanced fibrosis (Ishak 3-6), those without serologic evidence of prior exposure were vaccinated with either Havrix HAV, Engerix( HBV, or the TWINRIX HAV/HBV combination vaccine as appropriate, and response was defined as the development of anti-HAV or anti-HBV surface antibodies. Of the 162 eligible patients, the prevalence of prior exposure to HAV and HBV was 30 and 18%, respectively. Of the 84 patients vaccinated, 38% received Havrix, 14% Engerix, and 48% TWINRIX. The response to the HAV vaccine was 75% in those receiving Havrix compared to 78% receiving TWINRIX. In contrast, the response to HBV vaccination was 42% in patients receiving Engerix compared to 60% in those vaccinated with TWINRIX (difference 18.3%; OR 0.29; 95% CI: 0.57-7.79). The presence of diabetes was the only risk factor identified for reduced HBV response (P = 0.01). Responses to both HAV and HBV vaccines when administered alone or in combination were lower than expected in patients with HCV and advanced fibrosis, especially in those with diabetes. The observation that the decline in HBV vaccine response was somewhat lower when this was administered alone as opposed to the combination A/B vaccine suggests that the administration of a combination vaccine may enhance the vaccination response to HBV.

Use of an accelerated immunization schedule for combined hepatitis A and B protection in the corporate traveler. J Occup Environ Med. 2008;50:945-950. [PMID: 18695453 DOI: 10.1097/JOM.0b013e3181808081]

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.

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.

Rapid and sustained immune response against hepatitis A and B achieved with combined vaccine using an accelerated administration schedule

BACKGROUND

Combined hepatitis A and B vaccine administered on an accelerated schedule provides a rapid immune response against both hepatitis A and B viruses, which might be especially relevant for individuals who need protection quickly.

METHODS

A prospective, open-label, randomized study to compare the immunogenicity and reactogenicity of the combined hepatitis A and B vaccine Twinrix (GlaxoSmithKline Biologicals, Rixensart, Belgium) (>or=720 EL.U/mL inactivated hepatitis A antigen and 20 microg/mL recombinant hepatitis B surface antigen [HBsAg]) administered at 0, 7, 21 to 30 days, and 12 months compared with concurrent administration of Havrix [GlaxoSmithKline Biologicals, Rixensart, Belgium (>or=1440 EL.U/mL inactivated hepatitis A antigen)] at 0 and 12 months, and Engerix-B [GlaxoSmithKline Biologicals, Rixensart, Belgium (20 microg/mL recombinant HBsAg)] at 0, 1, 2, and 12 months in seronegative healthy adults.

RESULTS

At month 13, the anti-hepatitis B seroprotection rates (>10 mIU/mL) for the combined vaccine compared to the monovalent hepatitis B vaccine were 96.4% (95% CI: 92.7-98.5) and 93.4% (95% CI: 89.0-96.4), respectively. The anti-hepatitis A seroconversion rates were 100% in both groups (95% CI: 98.1-100). At day 37, the anti-hepatitis A seroconversion rates were similar in both groups (98.5% for combined vaccine, 98.6% for the monovalent vaccine group), but the combined vaccine resulted in a statistically significantly ( p < 0.001) better anti-hepatitis B seroprotection compared to monovalent hepatitis B vaccine, 63.2% versus 43.5%, respectively. The reactogenicity profile was similar in both study groups.

CONCLUSIONS

The combined hepatitis A and B vaccine administered on an accelerated schedule was at least as immunogenic and as well tolerated as the corresponding monovalent vaccines.

Prevention of hepatitis A by Havrix: a review

Hepatitis A is one of the most common vaccine-preventable infectious diseases in the world. With at least 1.5 million cases of hepatitis A worldwide each year, disease management constitutes a substantial economic burden. The first effective vaccine against hepatitis A, Havrix was introduced in 1992. This review summarizes data accumulated following more than a decade of clinical experience with this vaccine and compares clinical data with other currently available hepatitis A vaccines. Based on this data and on the current immunological knowledge, a recent consensus concluded that hepatitis A vaccines induce lifelong protection, and thus booster vaccinations against hepatitis A are unnecessary in fully immunized, healthy people. In view of this, current regulatory recommendations for the use of hepatitis A vaccines are reviewed and possible future strategies identified.

Combined hepatitis A and B vaccines: a review of their immunogenicity and tolerability

Three combined hepatitis A and B vaccine preparations are commercially available in various countries: a two-dose paediatric formulation (Ambirix) [administered at months 0 and 6-12]; and a three-dose adult (Twinrix Adult) or paediatric (Twinrix Paediatric) formulation (administered at months 0, 1 and 6). The adult vaccine provides consistent, marked immunogenicity which is at least similar to that of its constituent vaccines used together and with a tolerability profile that is possibly improved. An accelerated, day-0, -7 and -21 regimen has also shown immunogenicity similar to that of the monovalent vaccines given concurrently, and now has an emerging role in adults likely to travel to hepatitis A virus (HAV) and/or hepatitis B virus (HBV) endemic regions within 1 month. The adult vaccine appears effective and generally well tolerated when given concurrently with monovalent typhoid vaccine (Typherix). Immunogenicity of the two-dose paediatric vaccine is high and appears to be similar whether administered as a month-0, -6 or month-0, -12 schedule and when compared to that of the three-dose paediatric vaccine (months 0, 1, 6), both of which provide a similar degree of protection to the adult vaccine. Although both preparations also provide high end-of-schedule seroprotection against hepatitis B surface antigen, protection between the first and second doses of the two-dose regimen appears lower than with the three-dose schedule. Therefore, the three-dose paediatric vaccine is a practical option in individuals at risk of immediate exposure to HBV, while the two-dose regimen may have an important function in immunisation programmes in regions where such risk is low. Combined hepatitis A and B vaccines are generally well tolerated. The most frequently reported adverse events in clinical trials were injection-site pain and redness, and general fatigue and headache; most events were mild and transient. Pharmacoeconomic models suggest the combined vaccine is cost effective compared with no vaccine (in children/adolescents) or monovalent hepatitis B vaccine (in children/adolescents and prison inmates).

CONCLUSION

The three commercially available combined hepatitis A and B adult and paediatric vaccines are highly immunogenic and generally well tolerated; the adult vaccine demonstrates immunogenicity at least as marked as that of monovalent hepatitis A and B vaccines. While further research is required to confirm potential advantages such as improved cost effectiveness, the combined vaccines have established a key role in the prevention of hepatitis A and B in defined risk groups, and have an expanding role in population-based vaccination programmes with younger age groups.

The role of mobile phones in improving vaccination rates in travelers

RATIONALE

Noncompliance with vaccination schedules undermines the potential benefits of immunization. The purpose of this study was to evaluate whether a reminder of the next vaccine dose sent by the Short Messaging Service (SMS) to the vaccinee's mobile phone increases compliance with hepatitis A + B and hepatitis A vaccination schedule.

SUBJECTS AND METHODS

In this experimental, controlled study, the study group comprised travelers who went to the Internacional-Clínic Vaccination Centre between the 1st June and 30th September of 2001 for the standard immunization schedule against hepatitis A + B and against hepatitis A. Trained health-care workers entered the data into a computer to generate text messages reminding vaccinees of their scheduled doses. Two control groups, one from the same period of the same year including travelers from the third office (Control 2001) and the second, all travelers seen in the same period of the previous year (Control 2000), were used.

RESULTS

For the second hepatitis A + B dose, compliance in the study group (Message Groups) was 88.4% (83.3-92.2); in the Control 2001, 80.7% (76.3-84.4, relative risk [RR] 1.10 [1.02-1.17]); and in the Control 2000, 77.2% (73.3-80.5, RR 1.15 [1.07-1.22]). For the third hepatitis A + B vaccine dose, results were 47.1% (40.5-53.8); 26.9% (22.8-31.7, RR 1.75 [1.41-2.17]); and 23.6% (20.1-27.4, RR 2.00 [1.63-2.45]), respectively. As for the hepatitis A vaccine, compliance rates for the second dose were 27.7% (23.9-31.9); 16.4% (14.4-18.6, RR 1.69 [1.40-2.04]); and 13.2% (11.6-14.9, RR 2.10 [1.75-2.54]); respectively.

CONCLUSIONS

SMS seems to be an effective tool for increasing compliance with vaccination schedules.

Immunogenicity and reactogenicity of a combined high dose hepatitis A and hepatitis B vaccine, compared to that of Twinrix in healthy Indian children

BACKGROUND AND AIMS

Hepatitis A virus (HAV) and hepatitis B virus (HBV) are vaccine preventable important childhood acquired infectious diseases in developing countries. In the changing epidemiology of HAV, the utility of such a vaccine in India needs urgent attention. Further, the efficacy of two versus three dose schedule needs to be assessed to improve compliance.

SUBJECTS AND METHODS

One hundred healthy school children, aged 1-15 years were recruited in a randomised open study to receive either vaccination schedule: Group I: combined high-dose hepatitis A and B vaccine to be administered on a 0, 6 month schedule intramuscularly; Group II: to be administered on 0, 1, 6 month Twinrix (GlaxoSmithKline Biologicals, Rixensart, Belgium) schedule intramuscularly. The seroconversion (> or =1MIU/ml for anti-HBs antibodies and > or =33MIU/ml for anti-HAV antibodies) and seroprotection (anti-HBs > or =10MIU/ml after the third dose of vaccine) rates were determined at months 1, 2, and 7.

RESULTS

The mean age and gender was similar between groups: 7.9+/-2.6 years (range 3-15 years). At month 7 all subjects (100%) in both groups were seropositive for anti-HAV antibodies, Group I had higher anti-HAV titres at months 1 or 2 compared to Group II (P=0.025, P=0.040). Group II developed higher seroprotection rates (month 2, P=0.002, month 6, P=0.003) compared to Group I and higher titres (month 2, P=0.001, month 6 P=0.001) compared to Group I. At month 7, the geometric mean titres (GMTs) were comparable between groups and seroprotection reached 100% in both the groups. The incidence of any symptom per dose analysis reported during a 4-day follow-up period was significantly higher in Group I, 53% (52/98) of the documented doses compared to 37% (54/146) in Group II (P=0.018).

CONCLUSION

Twinrix vaccine is safe and highly immunogenic in Indian children. Further study of the high dose vaccine would determine if its two dose regimen is a feasible advantage.