Factors associated with hepatitis A susceptibility among men who have sex with men using HIV pre-exposure prophylaxis in Northeastern Brazil: A cross-sectional study

Hepatitis A virus (HAV) infection has disproportionately affected more men who have sex with men (MSM), occurring in outbreaks, despite being vaccine-preventable. We determined the prevalence and factors associated with HAV susceptibility among cisgender MSM on HIV pre-exposure prophylaxis (PrEP) in Northeastern Brazil. From September 30, 2021 to June 19, 2023, 282 cisgender MSM receiving HIV PrEP were enrolled into this cross-sectional study. Sociodemographic and clinical information were collected. Blood samples were collected for screening of sexually transmitted infections (STIs) and serum samples were tested for IgM and total anti-HAV antibodies. Non-reactive results for total anti-HAV antibodies were found in 106 of 282 (37.6%) participants. Factors associated with HAV susceptibility included age <30 years (prevalence ratio [PR]: 2.02; 95% confidence interval [95% CI]: 1.61-2.53), having health insurance (PR: 1.39; 95% CI: 1.19-1.64), sex only with cisgender men (PR: 1.52; 95% CI: 1.23-1.89), non-steady partner (PR: 1.20; 95% CI: 1.01-1.43) and no lifetime history of STIs (PR: 1.25; 95% CI: 1.03-1.53). Identifying clinical correlates of HAV susceptibility in key populations is a fundamental step towards development of public policy focused on prevention, especially following the recent hepatitis A outbreak in Brazil.

Coadministered pneumococcal conjugate vaccine decreases immune response to hepatitis A vaccine: a randomized controlled trial

OBJECTIVES

We explored the influence of coadministration on safety and immunogenicity of the most common travellers' vaccine hepatitis A (HepA) and the pneumococcal conjugate vaccine (PCV) increasingly used both at home and before travel.

METHODS

Volunteers aged ≥18 years (n = 305) were randomly assigned 1:1:1 into three groups receiving: 13-valent PCV (PCV13) + HepA, PCV13, or HepA. Anti-pneumococcal IgG concentrations, opsonophagocytic activity (OPA) titres, and total hepatitis A antibody (anti-HAV) concentrations were measured before and 28 ± 3 days after vaccination. Adverse events (AEs) were recorded over 4 weeks.

RESULTS

After vaccination, the anti-HAV geometric mean concentration was significantly lower in the PCV13+HepA than the HepA group: 34.47 mIU/mL (95% CI: 26.42-44.97 mIU/mL) versus 72.94 mIU/mL (95% CI: 55.01-96.72 mIU/mL), p < 0.001. Anti-HAV ≥10 mIU/mL considered protective was reached by 71 of 85 (83.5%) in the PCV13+HepA group versus 76 of 79 (96.2%) in the HepA group, p 0.008. The increases in anti-pneumococcal IgG and OPA levels were comparable in the PCV13+HepA and PCV13 groups, apart from a bigger rise in the PCV13+HepA group for serotype 3 (one-way ANOVA: serotype 3 IgG p 0.010, OPA p 0.002). AEs proved more frequent among those receiving PCV13 than HepA, but simultaneous administration did not increase the rates: ≥one AE was reported by 45 of 56 (80.4%) PCV13, 43 of 54 (79.6%) PCV13+HepA, and 25 of 53 (47.2%) HepA recipients providing structured AE data.

DISCUSSION

Coadministration of HepA and PCV13 did not cause safety concerns, nor did it impact the patients' response to PCV13, apart from serotype 3. However, coadministered PCV13 significantly impaired antibody responses to HepA.

Seroprevalence of hepatitis A virus antibodies among children and adolescents living in Northern Thailand: an implication for hepatitis A immunization

This cross-sectional study aimed to assess seroprevalence of hepatitis A virus (HAV) antibodies and identify factors associated with HAV seropositivity among children and adolescents aged 1-18 years who resided in Chiang Mai, Thailand. Sociodemographic characteristics, sanitation/hygiene, and history of HAV vaccination were collected. Anti-HAV IgG antibody was determined, and a level ≥ 1.0 S/CO defined HAV seropositivity. We enrolled 300 participants; median age 8.7 years, 54% male, and 13% overweight (BMI z-score: + 1 to + 2 standard deviation [SD]). Sixty-five participants (22%) were vaccinated against HAV. Overall, 84/300 participants (28%) demonstrated HAV seropositivity, of whom 55/65 (85%) and 29/235 (12%) were among vaccinated and unvaccinated participants (P < 0.001), respectively. Previous HAV vaccination (adjusted odds ratio [aOR] 47.2; 95% CI 20.0-111.8) and overweight (aOR 4.4; 95% CI 1.7-11.3, compared with normal weight [BMI z-score: - 2 to + 1 SD]) were significantly associated with seropositivity of HAV. In the stratified analyses, crowded bedroom (aOR 3.2; 95% CI 1.3-7.8, per one person increase) and overweight (aOR 5.0; 95% CI 1.8-13.7) were factors associated with HAV seropositivity among vaccinated and unvaccinated participants, respectively. Seroprevalence of HAV antibodies in healthy Thai children and adolescents was relatively low. Recommendation of HAV vaccination for these populations, particularly those with high-risk conditions, should be considered.

A Randomized Clinical Trial of 1-Dose vs Accelerated 2-Dose Schedule for Hepatitis A Virus (HAV) Revaccination Among People With Human Immunodeficiency Virus Who Were Nonresponders or Had Seroreversion After Primary HAV Vaccination

BACKGROUND

For people with human immunodeficiency virus (PWH) who have no serological responses to their primary hepatitis A virus (HAV) vaccination or have seroreversion after successful primary vaccination, the optimal revaccination strategy remains unclear.

METHODS

In this open-label, randomized clinical trial, PWH who tested negative for anti-HAV antibodies after receiving a standard 2-dose series of primary HAV vaccination were enrolled and assigned in a 1:1 ratio to receive either 1 dose (the 1-dose group) or 2 doses of HAV vaccine administered 4 weeks apart (the 2-dose group). Serological response rates and anti-HAV antibody titers were compared at weeks 24 and 48.

RESULTS

Of the 153 participants (77 in the 1-dose group and 76 in the 2-dose group), the overall serological response rates at week 48 after revaccination were similar between the 2 groups (2- vs 1-dose, 80.2% vs 71.4%, P = .20). However, anti-HAV antibody titers were consistently higher in the 2-dose group than in the 1-dose group. In subgroup analysis, PWH who were nonresponders to primary HAV vaccination were significantly more likely to mount a serological response after 2-dose HAV revaccination (68.4% vs 44.1%, P = .038). No severe adverse events were reported throughout the study.

CONCLUSIONS

Two-dose HAV revaccination administered 4 weeks apart yielded similar serological responses as 1-dose revaccination among PWH who were nonresponders or had seroreversion after primary HAV vaccination. The 2-dose revaccination schedule generated significantly higher anti-HAV antibody titers and was more likely to elicit serological responses at week 48 among PWH who were nonresponders to primary HAV vaccination. Clinical Trials Registration. NCT03855176.

Persistence of immunity against hepatitis A in Brazilian children vaccinated with a single dose of inactivated virus vaccine

In 2014, the Brazilian National Immunization Program implemented the universal vaccination against the hepatitis A virus (HAV) for children aged 12 months and older, applying a single dose of the inactivated virus vaccine. It is essential to carry out follow-up studies in this population, aiming to verify the longevity of HAV immunological memory. This study evaluated the humoral and cellular immune response of a cohort of children vaccinated between 2014 and 2015, and further investigated between 2015 and 2016, and who had their initial antibody response assessed after the single dose. A second evaluation took place in January 2022. We examined 109 children out of the 252 that took part in the initial cohort. Seventy (64.2%) of them had anti-HAV IgG antibodies. Cellular immune response assays were performed in 37 anti-HAV-negative and 30 anti-HAV-positive children. Production of interferon-gamma (IFN-y) stimulated with the VP1 antigen was demonstrated in 34.3% of these 67 samples. Of the 37 negative anti-HAV samples, 12 (32.4%) produced IFN-y. Among the 30 anti-HAV-positive, 11 (36.7%) produced IFN-y. In total, 82 (76.6%) children presented some type of immune response against HAV. These findings demonstrate the persistence of immunological memory against HAV in the majority of children vaccinated between 6 and 7 years with a single dose of the inactivated virus vaccine.

Sporadic Hepatitis A Virus PCR False-Positive Results Observed during Reflex Testing of Serum Samples Previously Tested for Anti-HAV Antibodies and Caused by Contamination with HAV RNA Present in the Reagents of the Commercial Anti-HAV Immunoassay

Hepatitis A diagnosis relies on serology and occasionally on hepatitis A virus (HAV) RNA detection. For timely diagnosis and the avoidance of drawing additional blood, molecular testing is often performed as reflex testing by using blood specimens that were initially sent for anti-HAV serology. Reflex molecular testing is preferably performed from different sample aliquots, but, for limited sample quantities, it uses samples that have been preprocessed in an immunoassay analyzer. In 2012, we first observed sporadic HAV RNA-positive cases that were inconsistent with patients' serological profiles and/or medical histories, suggesting that occasional laboratory contamination was causing false-positive PCR results. Multiple external quality assurance (EQA) and laboratory surface contamination checks were performed, questionable specimens were tested with various HAV RNA tests, and follow-up serum/stool samples were collected. All contamination-check samples and samples from healthy individuals tested HAV RNA-negative, and the laboratory successfully passed all EQAs. The HAV RNA-positive results were reproducible with various HAV RNA assays. No patients seroconverted, and their follow-up samples were consistently HAV RNA-negative. Finally, a detailed review of testing protocols revealed a correlation between HAV RNA false positivity and preceding anti-HAV testing with the Cobas-e411 automated immunoassay analyzer. HAV RNA was detected in the Cobas-e411 anti-HAV reagents, with the HAV sequences matching those from the false-positive samples. Preceding anti-HAV testing using two other immunoassay analyzers did not result in subsequent HAV RNA false positivity during reflex testing. The Cobas-e411 pipetting procedure with a single pipette tip collecting samples and anti-HAV reagents contaminated the original sample with the HAV RNA that was present in the immunoassay's reagents, thereby resulting in HAV RNA false positivity during the reflex testing. IMPORTANCE We present the first report of sporadic HAV PCR false-positive results that have been observed during the reflex testing of serum samples that have previously been tested for anti-HAV antibodies and have been caused by contamination with HAV RNA that is present in the reagents of the commercial anti-HAV immunoassay, with potentially serious clinical consequences. Although HAV RNA was consistently detected in the anti-HAV reagents of all three automated immunoassay analyzers that were in use in our laboratory, only the use of one analyzer and the corresponding commercial anti-HAV immunoassay reagents resulted in contamination that led to false positive HAV RNA results, and this was due to a peculiar pipetting mode of action in which the analyzer uses a single pipette tip to collect both anti-HAV reagents and a sample, which consequently causes the permanent contamination of the original sample with HAV RNA. Manufacturers should strongly consider the occasional need for reflex molecular testing from preprocessed samples and design their analyzers in a way that prevents contamination.

Masitinib Inhibits Hepatitis A Virus Replication

The hepatitis A virus (HAV) infection causes acute hepatitis. HAV also induces acute liver failure or acute-on-chronic liver failure; however, no potent anti-HAV drugs are currently available in clinical situations. For anti-HAV drug screening, more convenient and useful models that mimic HAV replication are needed. In the present study, we established HuhT7-HAV/Luc cells, which are HuhT7 cells stably expressing the HAV HM175-18f genotype IB subgenomic replicon RNA harboring the firefly luciferase gene. This system was made by using a PiggyBac-based gene transfer system that introduces nonviral transposon DNA into mammalian cells. Then, we investigated whether 1134 US Food and Drug Administration (FDA)-approved drugs exhibited in vitro anti-HAV activity. We further demonstrated that treatment with tyrosine kinase inhibitor masitinib significantly reduced both HAV HM175-18f genotype IB replication and HAV HA11-1299 genotype IIIA replication. Masitinib also significantly inhibited HAV HM175 internal ribosomal entry-site (IRES) activity. In conclusion, HuhT7-HAV/Luc cells are adequate for anti-HAV drug screening, and masitinib may be useful for the treatment of severe HAV infection.

The chronological changes in the seroprevalence of anti-hepatitis A virus IgG from 2005 to 2019: Experience at four centers in the capital area of South Korea

Although universal vaccination has been administered to toddlers, South Korea has had periodic nationwide outbreaks of acute hepatitis A since the late 2000s. We examined the chronological changes in the seroprevalence of anti-hepatitis A virus (HAV) immunoglobulin G (IgG) over the past 15 years (2005-2019). We retrospectively collected data from 45,632 subjects who underwent anti-HAV IgG testing without evidence of acute HAV infection at four centers in the capital area of South Korea between January 2005 and December 2019. The seroprevalence of anti-HAV IgG was analyzed according to age and compared among seven age groups and five time periods. Additionally, age-period-cohort analyses were used to identify the age, period, and cohort effects of the seroprevalence of anti-HAV IgG. The mean age of the enrolled subjects was 39.2 ± 19.2 years, and the average anti-HAV IgG positivity rate was 66.4%. During the 15 years, the seroprevalence of anti-HAV IgG in people aged 0 to 19 years significantly increased over time (P < .001). In people aged 20 to 29 years, the seroprevalence slightly decreased to that of the early 2010s (31.3% in 2005-2007 to 19.7% in 2011-2013) but rebounded to 39.5% in 2017 to 2019. In contrast, the seroprevalence of anti-HAV IgG in those aged 30 to 49 years decreased over time (P < .001). The seroprevalence of anti-HAV IgG in those aged 20 to 39 years in 2017 to 2019 was still less than 40%. In addition, the seroprevalence of anti-HAV IgG in people aged 50 to 59 years has recently decreased. Since the introduction of the universal vaccination, the seroprevalence of anti-HAV IgG in children and young adults has gradually increased. However, the seroprevalence of anti-HAV IgG in people in their 20s remains low, and the seroprevalence of anti-HAV IgG in people in their 30s and 40s is gradually decreasing. Therefore, a new strategy for HAV vaccination is needed for those in their 20s to 40s.

Assay Sensitivity Difference Can Induce Anti-Hepatitis A Virus IgM Non-Reactive But Total (IgM and IgG) Reactive Results in Early Acute Hepatitis A

Although anti-hepatitis A virus (HAV) IgM non-reactive and anti-HAV total (immunoglobulin [Ig] M and IgG) reactive results are generally interpreted as immunity to HAV, some early acute hepatitis A patients show the same results. We compared IgM detection sensitivity between anti-HAV IgM and anti-HAV total assays. Acute hepatitis A patients' samples were serially diluted and tested with Elecsys anti-HAV IgM and total assay (Roche Diagnostics). This resulted in anti-HAV IgM non-reactive but anti-HAV total reactive results. Samples of two hepatitis A patients showing false-negative anti-HAV IgM at initial presentation were analyzed with Elecsys, Atellica (Siemens Healthineers), and Alinity (Abbott Laboratories) HAV assays. Elecsys, Atellica, and Alinity anti-HAV IgM converted reactive on hospital day 3, whereas Elecsys and Atellica anti-HAV total results were reactive from hospital day 1. The anti-HAV total assay had higher sensitivity in detecting IgM antibodies than the anti-HAV IgM assay.

Comparative evaluation of four commercial analyzers for the serological screening of hepatitis A, B, C and HIV

BACKGROUND

Independent evaluations that deploy clinical patient samples are important in assessing the performance of commercial tests used for serological screening of viral hepatitis and HIV in clinical laboratories.

OBJECTIVES

We compared the analytical performance of Abbott Architect i2000SR, Abbott Alinity i, DiaSorin Liaison XL, and Siemens Atellica for the following analytes: anti-HAV IgG/anti-HAV total, anti-HAV IgM, HBsAg, anti-HBc IgM, Anti-HBc, HBeAg, anti-HBe, anti-HBs, anti-HCV, and HIV Ag/Ab. In addition, anti-HBc IgM, HBeAg, and anti-HBe were evaluated for Abbott Architect, Abbott Alinity and DiaSorin Liaison.

STUDY DESIGN

Pseudonymized clinical serum specimens (N = 98-200 for each analyte) were selected for the analysis according to their reactivity on the Abbott Architect. The results were compared against Abbott Architect and against consensus.

RESULTS

A generally high agreement was observed between the tests. Abbott Alinity had the lowest anti-HAV IgG/total specificity (75.9% against Abbott Architect and 83.0% against consensus). The comparatively low sensitivity of Siemens Atellica (78.2%), Abbott Alinity (87.5%) and DiaSorin Liaison (89.3%) for anti-HAV IgM against Abbott Architect may reflect a higher false-positive rate of Abbott Architect. Particular variation was observed in the sensitivity values of anti-HBc, HBsAg and HIV Ag/Ab between the test methods. DiaSorin Liaison anti-HBs gave consistently higher values as compared to the other tests.

CONCLUSIONS

The serodiagnostic methods for HIV and viral hepatitis of Abbott Architect, Abbott Alinity, DiaSorin Liaison, and Siemens Atellica performed well in comparison with each other. The observed differences between the tests will provide useful information for clinical laboratories in planning their workflows for screening and confirmation.

Evaluation of Potential Anti-Hepatitis A Virus 3C Protease Inhibitors Using Molecular Docking

Hepatitis A virus (HAV) infection is a major cause of acute hepatitis worldwide and occasionally causes acute liver failure and can lead to death in the absence of liver transplantation. Although HAV vaccination is available, the prevalence of HAV vaccination is not adequate in some countries. Additionally, the improvements in public health reduced our immunity to HAV infection. These situations motivated us to develop potentially new anti-HAV therapeutic options. We carried out the in silico screening of anti-HAV compounds targeting the 3C protease enzyme using the Schrodinger Modeling software from the antiviral library of 25,000 compounds to evaluate anti-HAV 3C protease inhibitors. Additionally, in vitro studies were introduced to examine the inhibitory effects of HAV subgenomic replicon replication and HAV HA11-1299 genotype IIIA replication in hepatoma cell lines using luciferase assays and real-time RT-PCR. In silico studies enabled us to identify five lead candidates with optimal binding interactions in the active site of the target HAV 3C protease using the Schrodinger Glide program. In vitro studies substantiated our hypothesis from in silico findings. One of our lead compounds, Z10325150, showed 47% inhibitory effects on HAV genotype IB subgenomic replicon replication and 36% inhibitory effects on HAV genotype IIIA HA11-1299 replication in human hepatoma cell lines, with no cytotoxic effects at concentrations of 100 μg/mL. The effects of the combination therapy of Z10325150 and RNA-dependent RNA polymerase inhibitor, favipiravir on HAV genotype IB HM175 subgenomic replicon replication and HAV genotype IIIA HA11-1299 replication showed 64% and 48% inhibitory effects of HAV subgenomic replicon and HAV replication, respectively. We identified the HAV 3C protease inhibitor Z10325150 through in silico screening and confirmed the HAV replication inhibitory activity in human hepatocytes. Z10325150 may offer the potential for a useful HAV inhibitor in severe hepatitis A.

Accuracy assessment of total or IgG Immunoglobulin to hepatitis A virus tests around immunity threshold

BACKGROUND

Anti-hepatitis A virus (HAV) antibody titers at 20 IU/L are assumed to correlate with protection against HAV challenge.

METHODS

We examined the accuracy and precision of currently in use immunoassays for total or anti-HAV IgG determination, by repeated testing of dilutions of the international anti-HAV standard, within a 10-50 IU/mL concentration range.

RESULTS AND CONCLUSION

Eight immunoassays were evaluated. All could confidently identify people who need to be vaccinated, or who might benefit from a booster vaccine: no positive interpretation for the 10 and 15 IU/mL concentrations. However, qualitative interpretation may differ from test to test in the 15-30 IU/mL range. This variation has to be taken into account when comparing seroprevalence data.

A single blind randomized phase 3 study to evaluate safety and immunogenicity of inactivated hepatitis A vaccine (HAPIBEVTM) in 1-15 years-old healthy hepatitis A vaccine-naïve children

The Biological E inactivated hepatitis A (HAPIBEV™) vaccine was developed by importing the Healive® vaccine bulk from China and fill-finish it in India. Healive® vaccine is approved in China for both children and adults. This study assessed the safety and immunogenicity of HAPIBEV™ vaccine as compared to the Havrix 720® vaccine of GlaxoSmithKline (GSK) pharmaceuticals when administered intramuscularly (IM) 6 months apart in 1-15 years old hepatitis A virus (HAV) vaccine naive children in India. This Phase 3, single blind, parallel, randomized, active-controlled, two-arm study was conducted at 8 centers in India in healthy HAV vaccine-naive children. Subjects were stratified into 2 age subsets (1-7 and 8-15 years) and randomly assigned to either BE-HAPIBEV™ or GSK's Havrix® vaccine and administered 2 IM injections 6 months apart. The immunogenicity evaluations included: (1) proportion of subjects who achieved the following at Day 210 from baseline: (a) seroconversion (≥20 mIU/mL) with anti-HAV immunoglobulin G (IgG) antibodies, (b) ≥4-fold increase in anti-HAV IgG antibodies, and (c) ≥2-fold increase in anti-HAV IgG antibodies concentration who were already seroconverted at baseline and (2) geometric mean concentrations (GMC) of anti-HAV IgG antibodies at baseline and Day 210. Safety was evaluated throughout the study. A total of 467 (89.8%) subjects completed the study. The non-inferiority criterion was met by HAPIBEV™ vaccine as seroconversion rates in both vaccine groups were 100%. Overall, other immunogenicity evaluations were either similar in both vaccine groups or higher in the HAPIBEV™ group compared with the Havrix® group. The safety profile was also comparable between HAPIBEV™ and Havrix® groups. The most common adverse event (AE) was injection site pain, and the majority of AEs were mild in severity. The HAPIBEV™ vaccine demonstrated an immunological and safety profile on par with Havrix® in 1-15 years old healthy HAV vaccine-naive Indian children. This study is registered with clinical trial registry of India bearing no: CTRI/2019/04/018384 on 02 Apr 2019.

Hepatitis A Virus Incidence Rates and Biomarker Dynamics for Plasma Donors, United States

The United States is currently affected by widespread hepatitis A virus (HAV) outbreaks. We investigated HAV incidence rates among source plasma donors in the United States since 2016. Serial donations from HAV-positive frequent donors were analyzed for common biologic markers to obtain a detailed picture of the course of infection. We found a considerable increase in incidence rates with shifting outbreak hotspots over time. Although individual biomarker profiles were highly variable, HAV RNA typically had a high peak and a biphasic decrease and often remained detectable for several months. One donor had a biomarker pattern indicative of previous exposure. Our findings show that current HAV outbreaks have been spilling over into the plasma donor population. The detailed results presented improve our comprehension of HAV infection and related public health aspects. In addition, the capture of full RNA curves enables estimation of HAV doubling time.

Long term Immunogenicity of Single Dose of Live Attenuated Hepatitis A Vaccine in Indian Children — Results of 15-Year Follow-up

Objectives

Methods

Results

Conclusions

Hepatitis A vaccination and its immunological and epidemiological long-term effects - a review of the evidence

Hepatitis A virus (HAV) infections continue to represent a significant disease burden causing approximately 200 million infections, 30 million symptomatic illnesses and 30,000 deaths each year. Effective and safe hepatitis A vaccines have been available since the early 1990s. Initially developed for individual prophylaxis, HAV vaccines are now increasingly used to control hepatitis A in endemic areas. The human enteral HAV is eradicable in principle, however, HAV eradication is currently not being pursued. Inactivated HAV vaccines are safe and, after two doses, elicit seroprotection in healthy children, adolescents, and young adults for an estimated 30-40 years, if not lifelong, with no need for a later second booster. The long-term effects of the single-dose live-attenuated HAV vaccines are less well documented but available data suggest they are safe and provide long-lasting immunity and protection. A universal mass vaccination strategy (UMV) based on two doses of inactivated vaccine is commonly implemented in endemic countries and eliminates clinical hepatitis A disease in toddlers within a few years. Consequently, older age groups also benefit due to the herd protection effects. Single-dose UMV programs have shown promising outcomes but need to be monitored for many more years in order to document an effective immune memory persistence. In non-endemic countries, prevention efforts need to focus on 'new' risk groups, such as men having sex with men, prisoners, the homeless, and families visiting friends and relatives in endemic countries. This narrative review presents the current evidence regarding the immunological and epidemiological long-term effects of the hepatitis A vaccination and finally discusses emerging issues and areas for research.

Immunogenicity persistence in children of hepatitis A vaccines Healive® and Havrix®: 11 years follow-up and long-term prediction

Background: Hepatitis A vaccine has been used in mass and routine public vaccination programs in China. Long-term follow-up studies are required to determine the duration of protection and the need for booster vaccinations. Methods: A prospective, randomized, open-label clinical trial was performed to compare the geometric mean concentration (GMC) and seroprotection rates of anti-Hepatitis A virus (HAV) antibodies elicited by the inactivated vaccines Healive and Havrix. 400 healthy children were randomly assigned 3:1 ratio to receive two doses of Healive or Havrix at 0 and 6 months. Persistence of anti-HAV antibodies for 5 years post immunization has been reported The current study reports new data at 11 years post immunization for the purpose of showing antibody persistence. Sensitivity analyzes were performed to assess the results. In addition, predictions for long-term antibody persistence were performed using a statistical model. Two different serological assays were used that were shown to be 98.3% concordant for detecting anit-HAV antibody. Results: GMCs were significantly higher following Healive compared to Havrix at 1, 6, 7, 66, 112 and 138 months post-vaccination. In addition, the GMCs obtained using sensitivity analysis were very similar to those obtained using the original models. Prediction analysis indicated that the duration of protection for both vaccines was at least 30 years after immunization, with a lower limit of the 95% confidence interval for GMC of greater than 20mIU/mL. Conclusions: Healive is more immunogenic than Havrix in children at 11 years post full immunization. Prediction analysis indicated at least 30 years of antibody persistence for both vaccines.

Predicting acute viral hepatitis serum markers (A and E) in patients with suspected acute viral hepatitis attending primary health care centers in Baghdad: a one year cross-sectional study

BACKGROUND

Viral hepatitis is an important preventable infectious disease with various rates of occurrence in different areas of the world. The main objective of the present study was to evaluate the role of some risk factors in predicting a positive acute viral hepatitis marker among patients with suspected acute viral hepatitis in a primary health care setting in Baghdad. Besides, finding out the occurrence of jaundice, contribution of viruses A and E to the cases that have occurred in Baghdad province was also searched for.

METHODS

Over a period of 1 year a descriptive cross sectional study was carried out at the primary health care centers in Baghdad. A questionnaire form was used to collect data about demographic factors and the results of the investigations. Total serum bilirubin and bilirubin in urine were done at the primary health care center laboratory. The rest of the sera samples were sent to Hepatitis referral Lab at Central Public Health Laboratory (CPHL) to be tested for anti HAV IgM and anti HEV IgM using ELISA technique.

RESULTS

A total of 7,576,372 consultations to primary health care centers were recorded in Baghdad. Among those a total of 2,692 cases (35.5 per 100,000 consultations) were labeled as acute viral hepatitis cases. A positive hepatitis viral marker (A, B, C and E) was found in 1,332 cases (17.6 per 100,000 consultations). More than two fifths (44.8%) of cases were positive for anti-HAV antibodies and another 1.6% had positive anti-HEV antibodies.

CONCLUSION

During 1 year period, the rate of occurrence of suspected acute viral hepatitis cases was 35.5 per 100000 of consultations to the primary health care centers in Baghdad. Of the total suspected cases, only 17.6 per 100000 of the consultations were positive for one of the viral hepatitis markers. Those who tested positive for one of the viral hepatitis markers represent 49.5% of the suspected cases. Proportion of anti HAV IgM positive tests among suspected cases was 44.8%. Factors that were able to predict positive Anti HAV IgM were (younger age group, negative history of cupping or tattooing, negative past history of jaundice). Male gender was the least important predictor of a positive case for anti HAV IgM. Proportion of Anti HEV IgM positive tests among suspected cases was 1.6%. Of the factors studied, only age was able to predict a positive Anti HEV IgM in those more than 15 years. Further studies are recommended.

[Cost-utility analysis on universal childhood hepatitis A vaccination in regions with different anti-HAV prevalence rates of China]

OBJECTIVE

To explore the inputs and outputs of areas with different anti-HAV prevalence rates on universal childhood vaccination, and to provide a scientific basis for the formulation of the immunization strategy.

METHODS

Since hepatitis A vaccination was scheduled at 12 and 18 months of age for all the healthy children, a single cohort including 1 000 000 individuals was formed in 2009, using the Chinese inactivated vaccine. Decision analysis was used to build Markov-decision tree model. The universal childhood hepatitis A vaccination was compared with non-vaccination group to evaluate the number of symptomatic infection, hospitalization, death, quality-adjusted life years (QALYs) lost, and the incremental cost-utility from the health system and the societal perspectives. Outcomes of the vaccination for the next 70 years were also predicted. The process of analysis was run separately in five regions defined by the anti-HAV prevalence rates (around 50%, 50% - 69%, 70% - 79%, 80% - 89% and > 90%). Sensitivity analysis was performed to test the stability or reliability of the results, and to identify sensitive variables.

RESULTS

The study projected that, in the lowest, lower, and intermediate infection regions, the cost and output indicators of universal childhood hepatitis A vaccination were all lower than non-vaccinated group. Universal vaccination could gain QALYs and save both costs from the health system or the society. In the regions with higher infection rate, the output indicators of universal childhood hepatitis A vaccination were lower than in those non-vaccinated groups, except for the number of death due to hepatitis A, which had a 20 cases of increase. The model also predicted that in the highest infected region, universal vaccination would increase 4 560 814 and 5 840 430 RMB Yuan in the total costs from both the health system and the societies, respectively, when compared to the non-vaccination groups. Universal vaccination would also decrease the numbers of symptomatic infection, hospitalization, and QALYs lost, but would increase 51 deaths due to hepatitis A, and 1507, 1929 more RMB Yuan for each QALY gained from the health system and societal respectively, in the regions with highest infection rate. Sensitivity analyses discovered that the infection rate among those susceptible population and the proportion of those who initially under protection but subsequently lost their immunity every year, were the two main sensitive variables in the model.

CONCLUSION

Our research discovered that the universal vaccination strategy should be based on the protective period of the vaccine and the anti-HAV prevalence in different endemic areas.

Immunogenicity of an inactivated hepatitis A pediatric vaccine: three-year post-booster follow-up

The persistence of anti-hepatitis A virus antibody concentrations was followed over 3 years in 177 healthy children following primary and booster vaccination with an inactivated hepatitis A vaccine, Avaxim 80 pediatric. Seroconversion rates (post-immunization anti-HAV antibody concentration >or=20 mIU/mL) and geometric mean concentrations (GMC) were estimated for each of three age groups: 18 month--3 years, 4--8 years, and 9--15 years. Only subjects who were initially HAV-seronegative at inclusion (<20 mIU/mL) were analyzed. Follow-up visits at years 1, 2, and 3 involved 177, 149, and 135 children, respectively. A decline in GMCs of about 74% occurred during the first year, from 3,060 to 814 mIU/mL overall, but did not continue during years 2 and 3. All subjects remained seropositive (antibody concentration >or=20 mIU/mL), with overall GMCs of 814, 891, and 924 mIU/mL in years 1--3, respectively. The inactivated hepatitis A study-vaccine resulted in sustained seroprotective antibody concentrations in 100% of these children, without a significant decline in antibiotic concentrations over the 3 years following booster injection, thus demonstrating the long-term protection expected with this vaccine.

Seroprevalence of hepatitis A antibodies in relation to social factors--a preliminary study

INTRODUCTION

Hepatitis A is a benign illness in children with the rare possibility of fatal complications. Although an endemic disease, very few studies have been done in children regarding the seroprevalence of hepatitis A antibodies in Sri Lanka.

OBJECTIVES

(i) To document the seropositivity for hepatitis A in a group of children admitted to a paediatric ward. (ii) To determine the relationship of hepatitis A viral infection to social factors in these children.

METHOD

A prospective, descriptive, cross-sectional study was carried out in a ward at the Lady Ridgeway Hospital for 7 months from September 2001. Children admitted on predetermined days, needing venepuncture for their presenting illness, were studied while those who were seriously ill were excluded. Written consent was obtained and a questionnaire with details of socio-economic conditions, personal hygiene practices of the mother, access to water and sanitation and health related behaviour was administered. Total antibodies to hepatitis A were detected by ELISA on a sample of blood taken from each patient.

RESULTS

Two hundred and eighty eight samples of blood were analysed. None of the children were immunised against hepatitis A. There were 158 boys (54.9%). Thirty one (10.8%) of the 288 patients had antibodies against hepatitis A. The seroprevalence was 11.6% in children under 10 years of age. Majority (78%) were from families with a monthly income of less than Rs 10,000/-. Fifteen (48.4%) of the 31 seropositive children were from families earning less than Rs 5000/- per month. Belonging to social classes IV and V and having mothers with only primary education were factors significantly associated with seropositivity. No significant difference in the presence of antibodies was observed regarding the personal hygiene practices analysed and access to basic amenities. Health related behaviour practices analysed were significantly associated with the presence of hepatitis A antibodies.

CONCLUSIONS

Seroprevalence of 10.8% was observed in a selected group of children. Factors such as poor socio-economic background and having mothers with only primary education were associated with hepatitis A virus (HAV) antibodies as were certain health related behaviour practices of children.

Hepatitis A vaccines

Hepatitis A, an acute usually self limiting infection of the liver is one of the most common vaccine-preventable infectious disease in the world. Effective vaccines which provide long term immunity against hepatitis A have been available since 1992. They are of known good quality, well tolerated with no serious adverse events and have been successfully used to protect different populations from infection as well as interrupt outbreak in closed communities. Mathematical models estimate the long term persistence of antiHAV antibodies to be more than 25 years. Vaccination efforts should be supplemented by health education and improved sanitation. Planning for large scale immunization programmes against hepatitis A should take into consideration epidemiological and cost benefit studies.

[Hepatitis A]

Hepatitis A infection is known since the ancient Chinese, Greek and Roman civilizations but the first documented report was published in the eighteenth century. The hepatovirus belongs to the Picornaviridae family, and carries a single strand RNA. There are 7 genotypes. Antibodies of the IgM and IgA classes, during natural infections, appear early in the serum, together with the first clinical manifestations of the disease, but they may also appear at the end of the first week of infection. There is a spectrum of clinical presentation: asymptomatic infection, symptomatic without jaundice and symptomatic jaundiced. A rare fatal form of hepatitis has been described. Diagnosis of the hepatitis A infection is confirmed by the finding of IgM anti-HAV antibodies, routinely performed using an ELISA test. Treatment is supportive. Intramuscular anti-A gamma globulin is used for passive immune prophylaxis, and there is an efficient vaccine for active immune prophylaxis.

Immunofluorescent detection and quantitation of hepatitis A virus in sewage treatment effluent and on agri-food surfaces using scanning confocal microscopy

An immunofluorescent (IF) assay was developed for specific detection and quantitation of hepatitis A virus (HAV) in sewage treatment effluent or attached to stainless steel, copper, high density polyethylene and polyvinyl chloride surfaces. Polyclonal antibodies were produced in rabbits and characterized for specificity to HAV. Purified anti-HAV antibodies were used in combination with ALEXA-anti-rabbit conjugate and confocal microscopy for detection and quantitation of HAV in effluent samples. Using this immunological approach, as little as 2 x 10(5) PFU/ml were detected and the signal generated was proportional to the concentration of HAV up to 2 x 10(8) PFU/ml. Counts obtained by IF assay were highly correlated with those of the SYBR Green II nucleic acid labelling method (r(2)=0.995) and conventional plaque assay (r(2)=0.988). The IF assay described is rapid (3 h), sensitive, specific to HAV and suitable for qualitative as well as quantitative studies.

Long-term immunogenicity of an inactivated virosome hepatitis A vaccine

The aim of this study was to predict the long-term protection induced after immunisation with inactivated, aluminium-free virosome hepatitis A vaccine. The study population consisted of adult volunteers enrolled in four different clinical trials. Lower 95% confidence interval limits and seroconversion rate were calculated by using a linear mixed model to estimate the persistence of serum antibodies over time. To assess the robustness of the mathematical model, several sensitivity analyses were performed with more conservative protective threshold (20 mIU/ml vs. 10 mIU/ml), higher yearly decline rate, and exclusion of volunteers who had increasing titres over time. Based on 190 volunteers with at least two valid assessments of titres from year 3 onward, the median duration of protection was 55.5 years, with a lower limit of the 95% CI of 48.7 years. Duration below 25.3 years was predicted for only 5% of the subjects. Women tended to have higher titres to start with, but their rate of decline was higher, resulting in similar duration of protection overall. The use of a more conservative threshold, higher yearly decline rate, and exclusion of volunteers with increasing titres over time did not affect these results. According to this model, 95% of the volunteers should have anti-HAV titres above the minimum protective threshold for 20 years or more following immunisation with two doses of this aluminium-free vaccine.

Prevalence of markers for hepatitis A, B and C in the German population. Results of the German National Health Interview and Examination Survey 1998

The prevalence of serological parameters indicative of infection with hepatitis A, B and C was determined using sera collected from representative population samples in the former East German (new) federal states and the West German (old) federal states during the German National Health and Examination Survey in 1998. Sera were tested for antibodies to hepatitis A virus (HAV), to hepatitis B core antigen (HBc) and to hepatitis B surface antigen (HBsAg), hepatitis C Virus (HCV), as well as for the presence of HBsAg and HCV-RNA. The mean weighted prevalence of anti-HAV was 46.5% (95% CI: 45.3-47.7) and increased markedly with age. The mean weighted prevalence of past infection with hepatitis B was 7.7% (95% CI: 7.0-8.4) in the old federal states and 4.3% (95% CI: 3.2-5.3) in the new federal states, corresponding to an overall prevalence of 7.0% (95% CI: 6.4-7.6). The mean weighted prevalence of HBsAg carriage was 0.6% (95% CI: 0.4-0.8), while the prevalence of HCV antibodies was 0.4% (95% CI: 0.2-0.5).

Changing scenario of hepatitis A virus and hepatitis E virus exposure among the primitive tribes of Andaman and Nicobar Islands, India over the 10-year period 1989-99

The Andaman and Nicobar Islands, Union Territory of India, are home to six primitive tribes. Studies carried out earlier among these tribes revealed very high rates of hepatitis B infection. We have now studied hepatitis A and E infection among them. A total of 951 serum samples were collected from four accessible tribes (Nicobarese, Shompens, Onges and Great Andamanese) and tested for antibodies against hepatitis A and E viruses. In addition, 240 serum samples collected a decade earlier from age-stratified Nicobarese were also screened. Hepatitis A virus (HAV) infection was found to be highly endemic among all the tribes, whereas hepatitis E virus (HEV) infection was common among the Nicobarese and Shompens. The age group-wise prevalence of these infections among the Nicobarese showed different patterns, HAV prevalence rising significantly from those aged 10 years and thereafter reaching a plateau, whereas HEV prevalence was found to be more evenly distributed over all age groups, but rising somewhat after 30 years of age. Over the last decade, the prevalence of HAV among the Nicobarese has declined slightly, particularly in those aged 10 years or less whereas HEV infection has more than doubled over all age ranges. Different HEV prevalence observed among the tribes could not be attributed to differences in sanitation or water supply. This fact and the different age-wise patterns of HAV and HEV prevalences is suggestive of different modes of transmission of HEV that are not shared. The highest rates for HEV were among those tribes which reared pigs suggesting that pigs might serve as reservoir of HEV. Further studies are needed, however, to validate these findings.

Immunogenicity and reactogenicity of a combined hepatitis A and B vaccine in healthy Chilean subjects

OBJECTIVES

A combination vaccine against hepatitis A and B provides the opportunity for simultaneous protection against both diseases with a single vaccine. This clinical study investigated the reactogenicity and immunogenicity of a combined hepatitis A and B vaccine (Twinrix, GlaxoSmithKline Biologicals, Rixensart, Belgium) in healthy Chilean adults between 18 and 40 years of age.

METHODS

In total, 345 healthy, seronegative health care workers were enrolled and randomized to three groups who received one of three lots of Twinrix on a 0-, 1- and 6-month schedules. Blood samples were screened 1 month after each dose for anti-HAV and anti-HBs antibodies. Reactogenicity after each dose was assessed using diary cards.

RESULTS

The nature and incidence of symptoms were similar to those reported for other Twinrix studies. Very few symptoms were scored as severe. Upon completion of the vaccination, all subjects had anti-HAV antibodies with titers $6000 mIU/mL, and all but one were protected against hepatitis B, with titers $4000 mIU/mL.

CONCLUSIONS

We have demonstrated the high immunogenicity and tolerance of the combined hepatitis A and B vaccine. Combined vaccination has the advantage of offering dual protection with a reduction in the number of injections needed, lower associated costs, and a positive impact on compliance.

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.

Age-specific prevalence of antibodies to hepatitis A in Santiago, Chile: risk factors and shift in age of infection among children and young adults

Transition from high to lower endemicity of hepatitis A virus (HAV) infection may portend increased public health burden with the shift of infection to older ages and increasing morbidity and mortality. This report describes age-specific prevalence of antibodies to HAV (anti-HAV) among children and young adults in Santiago, Chile, compared with previous prevalence data and assesses factors predictive for anti-HAV. In 1998, a serosurvey was performed in Metropolitan Santiago, designed to enroll a representative, age-stratified population on the basis of area of residence. A total of 784 individuals (age range, 1-24 years) were enrolled. Anti-HAV prevalence by year of life was as follows: ages 1 to 4, 12.5%; 5 to 9, 26.2%; 10 to 14, 43.4%; 15 to 19, 57.4%; 20 to 24, 73.9%. Adjusting for age, factors associated (inversely) with anti-HAV included residential areas of higher socioeconomic status (SES), parental education, and household characteristics of potable water, municipal sewage system, and the presence of a toilet or refrigerator in the house. In logistic regression analysis, only maternal years of education and residence in areas of higher SES remained independently associated with anti-HAV. Excluding those from higher SES areas, comparison of the age-specific anti-HAV prevalence data from previous studies of similar methodology in areas of lower SES revealed consistent decreases across all age groups; the age-standardized prevalence for this age range (1-24 years) dropped from 53.7% in 1990 to 40.6% in 1998. In light of the growing pool of susceptible individuals at older ages, with HAV continuing to circulate in the communities, evaluation of the feasibility of vaccination programs would be judicious.

Hepatitis A virus infections in the United States: model-based estimates and implications for childhood immunization

OBJECTIVE

The high prevalence of antibody to hepatitis A virus (HAV) in the US population suggests that the incidence of infection is much higher than reported, but the infection rate is difficult to measure directly because of anicteric infection and underreporting. We present a model that reconciles the reported incidence of hepatitis A with the observed prevalence of antibody to HAV and provides an estimate of the true incidence of HAV infection.

METHODS

In the model, reported incidence of hepatitis A in the United States was adjusted to account first for anicteric infection and then for underreporting and declining incidence over time such that the prevalence predicted by the model approximated that observed in 2 nationwide surveys.

RESULTS

The model showed incidence in the susceptible population declining by 4.5% per year. As incidence declined early in the 1900s, the average age at infection increased, leading to a paradoxical increase in the incidence of icteric infection followed by a slow decline. The model estimated approximately 270 000 (range: 190 000-360 000) infections annually from 1980 to 1999, 10.4 times the number of hepatitis A cases actually reported during this period. More than half of these infections occurred in children who were younger than 10 years, most of which would have been clinically unrecognizable as hepatitis.

CONCLUSIONS

These results suggest a large reservoir of infection in children and that interruption of transmission in children may substantially reduce incidence of hepatitis A overall.

Hepatitis a outbreak in a public school in Rio de Janeiro, Brazil

From June 1 to July 1 1999, an outbreak involving 25 cases of hepatitis A occurred in a public school in Rio de Janeiro, Brazil. Since these cases were notified to the State Health Department, the National Reference Center for Hepatitis Viruses (CNRHV) was required to investigate the extent of hepatitis A virus (HAV) dissemination. Blood samples from all students were tested for IgM and total anti-HAV antibodies using a commercial enzyme-linked immunoassay (ELISA). At the same time, a questionnaire was completed in order to identify possible risk factors for HAV infection. The environmental investigation showed that there was no fecal contamination of the water supply. The epidemiological investigation demonstrated that almost 50% of this population was susceptible to HAV infection and probably person-to-person transmission was the principal mode of virus dissemination. In this situation, a massive vaccination campaign could control the HAV infection.

Effectiveness of hepatitis A vaccine in a former frequently affected community: 9 years' followup after the Monroe field trial of VAQTA

The Kiryas Joel community in Monroe, N.Y. was the site of the first clinical trial which proved the protective efficacy of hepatitis A vaccine. The vaccine used was VAQTA J. Med. Virol (hepatitis A vaccine, inactivated). In the 9 years since the trial ended vaccination of infants reaching 2 years of age has continued along with monitoring for hepatitis A cases. The prevaccine pattern of frequent outbreaks has converted to a sustained pattern of no outbreaks, despite sporadic introduction of hepatitis A into the community in nonvaccinees. Community use of VAQTA in children 2 years of age and older has proven capable of providing long-term prevention of hepatitis A outbreaks in a formerly frequently affected community despite prolonged sporadic introduction of the virus.

[Seroprevalence of hepatitis A and cost evaluation of different vaccination strategies against hepatitis A virus in patients with chronic hepatitis C in France]

OBJECTIVES

To prospectively determine the prevalence of total hepatitis virus A antibodies in patients with chronic hepatitis C and to evaluate the direct costs of several vaccination strategies against hepatitis A virus in these patients.

METHODS

From April 1 to July the 31 1998, 219 patients with hepatitis C virus antibodies underwent a systematic testing for total hepatitis virus A antibodies (MEIA-AXSYM, Abbott laboratories). The prevalence of hepatitis A virus antibodies was evaluated according to age and suspected way of hepatitis C contamination. This prevalence has been compared to that in individuals undergoing a check-up provided by the national health insurance system stratified by age. Direct costs of 2 vaccination strategies "A" and "B" were evaluated according to age (<40 vs > 40 years) and number of vaccine doses (1 or 2). "A" strategy included the systematic vaccination of all patients without determining the presence of total hepatitis A antibodies. "B" strategy included testing for total hepatitis A antibodies and vaccination of seronegative patients. The costs of these two strategies (A and B) were calculated with one and two vaccine doses.

RESULTS

The prevalence of total hepatitis A antibodies was 76% in the entire population. It increased after the age of 35 and was statistically higher in patients who were older than 40 than in patients younger than 40. This prevalence was not significantly different from that in individuals who underwent a check-up provided by the national health insurance system stratified according to age. "B" strategy with 2 vaccine doses was less expensive that A strategy in the whole population and in patients younger than 40. This strategy was less expensive with 1 vaccine dose except in patients who had recently screened positive for hepatitis C antibodies younger than 40 when it induced an increased in direct cost due to the low prevalence of total hepatitis A antibodies in these patients.

CONCLUSIONS

In patients with hepatitis C antibodies with a high prevalence of total hepatitis A antibodies, testing for the prevalence of these antibodies before vaccination decreases the direct cost of this vaccination.

A new accelerated vaccination schedule for rapid protection against hepatitis A and B

BACKGROUND

Increasing travel stresses the requirement for rapid protection against infections such as hepatitis A and B.

METHODS

This randomised, multicentre study investigated an accelerated vaccination schedule using a combined hepatitis A and B vaccine (Twinrix, Smithkline Beecham Biologicals) compared with simultaneous administration of the two corresponding monovalent vaccines. The combined vaccine was administered on days 0, 7 and 21, whereas the comparison group received hepatitis A vaccine on day 0 and hepatitis B vaccine on days 0, 7 and 21. All subjects received booster vaccination at month 12.

RESULTS

At month 1, 100% of subjects in the combined group and 99% of the controls were seropositive for anti-HAV antibodies. The corresponding seroprotection rates for anti-HBs antibodies were 82.0 and 83.9%, respectively. Examination of the 95% confidence intervals (CIs) for the treatment differences showed the two vaccines to be equivalent in terms of immunogenicity 1 week after the initial vaccination course. Just prior to the booster, the seropositivity rate for anti-HAV was 96.2% in the combined group and 95% in the control group. For anti-HBs, this was 94 and 91.6%, respectively. All subjects were seropositive for anti-HAV and seroprotected against hepatitis B at month 13. The anti-HAV GMCs were 9571mIU/ml with the combined vaccine and 5206mIU/ml in control subjects. The anti-HBs titre was 26002 and 29,196mIU/ml, respectively. Both groups had a similar reactogenicity profile.

CONCLUSIONS

The accelerated schedule of the combined vaccine provides a good immune response against hepatitis A and B antigens and is suitable for last minute immunisation.

A two-dose combined vaccine against hepatitis A and hepatitis B in healthy children and adolescents compared to the corresponding monovalent vaccines

BACKGROUND

Immunization against hepatitis A and B has been available for some time, protecting against both infections. With a view to achieving further reduction in the number of interventions and increasing convenience of the vaccinee, we investigated the reactogenicity and immunogenicity of a combined hepatitis A and B vaccine in healthy 4- to 20-year-old subjects at a 0, 6-month schedule.

METHODS

Two hundred forty-eight study subjects were allocated to two study groups and received either two doses of the combined hepatitis A and B vaccine (68% of subjects) or the corresponding monovalent hepatitis A and hepatitis B vaccines (32% of subjects) concomitantly in opposite arms. Reactogenicity was assessed via diary cards after each vaccination. Serum samples were analyzed at months 1, 2, 6, and 7.

RESULTS

All vaccines were well tolerated and very few symptoms were scored as severe. All but one subject seroconverted for anti-hepatitis A virus (anti-HAV) antibodies (98.6%) and 100% of subjects seroconverted for anti-hepatitis B (HBs) antibodies, with respective seroprotection rates of 98.7% for the combined vaccine group and 95.9% for the concomitant vaccine group (p >0.05), respectively. Geometric mean titers were higher in the group receiving the combined vaccine: 6,635 mIU/mL vs. 2,728 mIU/mL (p = 0.0001) for anti-HAV and 3,362 mIU/mL vs. 1,724 mIU/mL (p = 0.0205) for anti-HBs, respectively. Younger subjects had a stronger immune response compared to older subjects.

CONCLUSIONS

The combined hepatitis A and B vaccine was well tolerated at this two-dose schedule. The combined vaccine had higher immunogenicity, probably explained by a adjuvant effect of the antigens. Vaccination programs requiring fewer injections will most likely have a positive impact on compliance rate and comfort of the vaccinee.

Viral hepatitis in South African healthcare workers at increased risk of occupational exposure to blood-borne viruses

The prevalence of hepatitis A, B and C antibodies was measured in a group of healthcare workers (HCWs) at increased risk of occupational acquisition of blood-borne viruses (N=402) from a large, urban referral hospital in South Africa. The aims of this study were to determine the immunity of HCWs to these agents and to recommend policy for the protection of HCWs against occupational exposure to viral hepatitis in this country. Race, sex and age were shown to be important factors influencing the presence of hepatitis A (HAV) antibodies. Most black HCWs (96.2%) are protected from HAV infection. Females have significantly higher HAV antibodies compared with males and antibodies increase with increasing age. Hepatitis B antibodies (anti-HBs) were found in 30.6% of HCWs. Anti-HBs levels were significantly associated with a past history of HBV vaccination. However, only a small proportion of HCWs (21.2%) could remember ever being immunized against HBV. For those individuals that did receive HBV vaccination (N=83), the mean number of years since their last vaccine was 6.2 years (SD +/- 3.5). HCV antibodies were found in 1.8% of HCWs at increased risk of occupational exposure. It was not possible to define whether these infections were occupationally acquired but genotyping of the HCV (in two of seven cases) showed genotype 5, the predominant South African genotype. New recommendations for the prevention of viral hepatitis in HCWs in South Africa are made, including pre-employment screening for HAV based on self-selection criteria, universal anti-HBs screening with HBV booster vaccination. HCV recommendations are based on appropriate education of HCWs about this infection and its prevention and a standardized post-exposure testing protocol.

Magnitude and quality of antibody response to a combination hepatitis A and hepatitis B vaccine

Interference between antibodies generated by a combination hepatitis A and B vaccine was investigated by evaluating the quantity and quality of anti-hepatitis A virus (HAV) and anti-hepatitis B surface antigen (HBs) antibodies generated by Twinrix (Hepatitis A Inactivated and Hepatitis B (Recombinant) Vaccine). The magnitude of the immune response was determined by a retrospective analysis of eight clinical trials, completed during stepwise development of Twinrix. The functionality of anti-HAV was evaluated by comparison of routine ELISA results with neutralization assays and was further characterized by defining the epitope-specificity of binding. Functionality of the anti-HBs response was not tested because a validated assay was not developed at the time this study was conducted. Results of all analyses demonstrated that the combination vaccine induced high antibody titers against hepatitis A and B and a functional anti-HAV response, with no evidence of immune interference to either viral antigen.

[The prevalence of hepatitis A in the Guadalajara province. Is Spain a country with low endemia?]

BACKGROUND

Spain, together with the other southern European countries, was considered to be an area with a moderate degree of endemia. This fact has consequences for tourists that visit these areas and for vaccination strategies. A prevalence study was proposed in order to get to know the situation of this infection in the Guadalajara province.

METHODS

284 specimens of serum were taken from patients who were classified according to their age, sex and place of residence (with more or less than 10.000 inhabitants). In these specimens the presence of hepatitis A antibodies were studied, using a Microparticule Enzyme Immunoassay (MEIA) (Abbott).

RESULTS

An increase in the prevalence was observed in older people, there is a low prevalence population (</= 5%) in people aged between 0-29 years and a high prevalence population (>80%) in adults aged between 30 and 74 years. No differences were observed related to sex. In the stratified analysis according to age, differences were observed between the groups from rural and urban origins.

CONCLUSIONS

The low prevalence of hepatitis A was found among the younger population, as seen in other studies carried out on a national level, and this together with a decrease in the frequency, means that Spain is included among the countries with low endemia. This fact has consequences for tourists who visit our country and for vaccination strategies, due to the increase in the number of adults who are susceptible to the infection.

Presumed common source outbreaks of hepatitis A in an endemic area confirmed by limited sequencing within the VP1 region

Hepatitis A virus isolates from anti-HAV IgM positive sera of 70 hepatitis cases in two outbreaks and 216 other cases in Central America, 136 sporadic cases and 53 cases from an hyper-endemic region in Costa Rica, were compared by phylogenetic analyses within the VP1 region. The outbreaks in all 531 cases, in 1992 and 1999, respectively, were presumed water borne. In the first outbreak, HAV RNA could be detected in 70% of the cases sampled during 6 weeks after onset of jaundice. In the hyper-endemic region of San Ramón in Costa Rica, 1,932 cases were registered between 1972 and 1985. All isolates belonged to subtype 1A. Background isolates from Costa Rica and El Salvador tended to form separate subclusters in the phylogenetic tree construction and were mostly unrelated to subtype 1A strains from other parts of the world. Based on their amino acid sequences, four HAV strains, all related to CR326 sampled in Costa Rica in 1960, were found to have circulated in the area during the last three decades. However, on the basis of nucleotide variability the isolates from the outbreaks could be distinguished from the strains from sporadic cases and sequence analysis could confirm the epidemiological homogeneity of both outbreaks. In the hyper-endemic region, 16 different sequences were encountered forming one single subcluster. Thus, limited sequencing within the VP1 region proved useful to identify outbreaks of hepatitis A in a highly endemic area, where most strains were local and only one subtype was prevalent.

The immunopathogenesis of hepatitis C virus infection

The outcome of HCV infection is determined by the interaction between the virus and the host immune system. The persistence of infection in most HCV-infected individuals, despite the presence of HCV-directed antibodies, suggests that such antibodies fail to induce viral clearance. Patients with self-limited hepatitis C have evidence of a polyclonal, multispecific CD8+ T-cell response along with a coordinated CD4+ T-cell response that is associated with eradication of HCV infection. Cytokines are produced both locally within the liver and systemically and may play an important role in controlling viral replication and contributing to hepatocellular damage through amplification of a nonspecific immune response. In most patients, the humoral, cellular immune, and cytokine response seem insufficient to eradicate infection. In its attempt to clear the virus from the liver, the immune system contributes to the hepatocellular injury seem in most chronically infected patients. A better understanding of the host's immune response may provide further insight on the pathogenetic mechanisms involved in development of chronic hepatitis and aid the development of better therapeutic strategies.

The epidemiology of hepatitis A in Rio de Janeiro: environmental and domestic risk factors

A serological study of hepatitis A was carried out in low-income areas scheduled for a major sanitation programme in Rio de Janeiro, Brazil. Blood spots were collected by finger puncture and transported on filter paper, and total antibodies to hepatitis A virus were detected by ELISA. Households were also interviewed to collect information on their environmental conditions and socio-economic status. A generalized linear model using a complementary log-log function was fitted to the data, using the logarithm of age as an explanatory variable to derive adjusted rate ratios (RR). The risk of infection was greater among households with 2-3 members per room (RR = 1.4; 95% CI = 1.04-1.8) or more than three per room (RR = 1.5; 95% CI = 1.2-2.0). People living on hilltops (RR = 1.5; 95% CI = 1.02-2.2), near to open sewers (RR = 1.2; 95% CI = 1.03-1.5) or lacking a kitchen (RR = 1.4; 95% CI = 1.08-1.9) were also at greater risk than others. The number of taps and water-using fittings in the house was associated with a protective effect (RR = 0.9 for each tap; 95% CI = 0.9-0.98). A significant protective association was found with maternal education but not with gender or household income. The results do not suggest a strong association with water quality. Ownership of a ceramic water filter was associated with a protective effect on the margin of significance, but the practice of boiling drinking-water was not, nor was the type of water source used. The results suggest that that the risk of infection with hepatitis A is determined by environmental variables in the domestic and public domains.

[Autoimmune hepatitis with prolonged IGM antibodies to HAV. Are serological markers reliable in ruling out a diagnosis of autoimmune hepatitis?]

We present the case of a 44-year-old woman who was referred to us for jaundice, choluria and acholia. Review of the patient's clinical history revealed that tests for hepatitis A virus (HAV) IgM antibody had been positive 4 and 2 years previously and continued to be so. The patient showed a score of 16 in the International Autoimmune Hepatitis Group's system when the HAV marker was not taken into account and a score of 13 when this marker was taken into account. The persistence of this viral marker for so many years in such patients is probably associated with polyclonal hypergammaglobulinemia. Consequently, we believe that the inclusion of this antibody as a negative datum in the diagnosis of autoimmune virus should be viewed with caution.

Antibodies to hepatitis A virus in Italian patients with chronic liver disease

To improve our knowledge for future hepatitis A virus (HAV) vaccination strategies we carried out a multicentre study on naturally acquired immunological protection against HAV in patients with chronic hepatitis in Italy. We enrolled 830 consecutive patients with chronic hepatitis on their first observation at one of the six Italian liver units participating in the study. Six hundred and fifty-eight patients (79.3%) were positive for total anti-HAV and 172 (20.7%) were negative. The anti-HAV negative patients were younger (median age 33, range 11-78) than the anti-HAV positive (median age 56, 18-87). There was a higher prevalence of cases with circulating anti-HAV among the 508 patients residing in southern Italy than in the 322 residing in northern Italy (88.8% vs. 64%, P < 0.001). No significant difference in the anti-HAV prevalence was observed between patients from northern Italy and those from southern Italy aged 0-30 years or in those over 60 years, while in those 31-60 years old there was a higher prevalence of anti-HAV positive patients from southern Italy (90.2% vs. 65.8%, P < 0.0001). Of the patients with liver cirrhosis in this study, only 3 of the 26 (11.5%) from northern Italy and 8 of the 228 (3.5%) from southern Italy had no immunological protection against HAV infection. The data suggest that the number of patients with chronic liver disease without naturally acquired immunity against HAV is substantial in Italy, particularly in the north of the country, and that new vaccination strategies are needed.

Cost analysis of two strategies for preventing hepatitis A virus infection in Spanish travellers to developing countries

Our objectives were to assess the prevalence of anti-hepatitis A (HAV) antibodies in Spanish travellers to developing countries and to carry out a cost analysis to allow the comparison of two vaccination strategies. Adult subjects were selected from among travellers to developing countries. Information was obtained on age, sex, destination, previous vaccination against HAV and having received immunoglobulin. Blood specimens were obtained for anti-HAV antibody determination. A total of 485 travellers were studied. The prevalence of anti-HAV antibody was 30.5% (95% CI 26-35). Antibody prevalence was inversely correlated with age: 9.8% in 18-25 years of age, rising to 75.4% in those 41-55 years of age. Cost analysis determined that the critical value of prevalence for vaccination with HAV vaccine was 37.5%. It was concluded that the youngest Spanish travellers lack anti-HAV antibodies. Vaccination without screening in those < or = 35 years of age and screening before vaccination for those > 35 years, are the preferred alternatives.

The epidemiology of hepatitis A infection in Palestine: a universal vaccination programme is not yet needed

In Palestine, there has been an increase in the reported incidence of acute hepatitis A virus (HAV) infection since 1995. Since overt clinical disease occurs only among adults, questions were raised whether or not a shift in the epidemiology of HAV has occurred. This is generally characterized by a decrease in the overall incidence rate and a shifting in the mean age of infection towards adolescence and early adulthood. The need for a vaccination programme is being discussed. To resolve this issue, we examined the prevalence of anti-HAV in a representative sample of 396 school children in the Gaza Strip. The prevalence of anti-HAV was 93.7% (95% CI: 91.3, 96.1%). Stratifying the prevalence by age showed that 87.8% (95% CI: 78.6, 97%) were HAV antibody positive by the age of 6. By the age of 14, almost 98% (95% CI: 92.7, 100%) were HAV antibody positive. This means that the majority of HAV infection is still taking place in early childhood, when it is usually asymptomatic and of little clinical significance. The results refuted the shifting epidemiology theory and we recommend that a vaccination programme against HAV infection is not yet needed. Alternative explanations for the increase in reported cases are discussed.

Control of a community-wide outbreak of hepatitis A by mass vaccination with inactivated hepatitis A vaccine

The epidemiology and control of hepatitis A virus was investigated during an outbreak of hepatitis A in a village in Israel. Postexposure administration of immune globulin to contacts was ineffective in controlling the outbreak. However, within 2 weeks of starting a mass immunization campaign with hepatitis A vaccine, the incidence of hepatitis A declined dramatically; the last case occurred 6 weeks after the immunization program began. The study demonstrated that while postexposure administration of immune globulin may diminish but not entirely arrest transmission of hepatitis A virus, active hepatitis A vaccination is a safe and effective intervention that can be used safely in hepatitis A virus antibody-positive children.

A randomized study of a flexible booster dosing regimen of VAQTA in adults: safety, tolerability, and immunogenicity

BACKGROUND

VAQTA (hepatitis A vaccine inactivated, Merck & Co., Inc., West Point, PA) is licensed for use in healthy adults in a two-dose schedule at 0 and 6 months.

OBJECTIVE

to determine whether the responses to a booster dose of VAQTA administered to adults 12 or 18 months after the first dose were similar to the response when the booster dose was administered 6 months after the first dose.

METHODS

healthy adults were randomized to receive 50-U of VAQTA at 6 (Group I), 12 (Group II), or 18 months (Group III) following receipt of Dose 1 on Day 0. Blood samples were collected immediately prior to Doses 1 and 2 and then, 4 weeks following Dose 2. Seropositivity rates (SPRs), geometric mean titers (GMTs) in milli-international units per milliliter (mIU/ml) and booster response rates (BRRs) were compared among treatment groups. Safety data were collected on Vaccination Report Cards.

RESULTS

no serious adverse experiences were reported, and the vaccine was well-tolerated by subjects in the three treatment groups. One month following the booster dose, SPRs and GMTs for Groups I, II, and III, respectively, were, 100% (102/102) and 6726.4 mIU/ml; 97.9% (93/95) and 4863.8 mIU/ml; 100% (86/86) and 6068.3 mIU/ml. The BRRs were 88.2% (Group I), 90.2% (Group II) and 94.2% (Group III).

CONCLUSION

responses to the booster dose were comparable regardless of the timing (i.e. 6, 12, or 18 months following Dose 1). Flexibility in the timing of the booster dose of VAQTA in adults would allow the vaccination schedule to be the same for adults, adolescents, and children and may increase the likelihood that adults receive the booster dose.