Decline in HAV-associated fulminant hepatic failure and liver transplant in children in Argentina after the introduction of a universal hepatitis A vaccination program

Viral etiologies of acute liver failure

Acute liver failure (ALF) is a rare cause of liver-related mortality worldwide, with an estimated annual global incidence of more than one million cases. While drug-induced liver injury, including acetaminophen toxicity, is the leading cause of ALF in the Western world, viral infections remain a significant cause of ALF and the most common cause in many developing nations. Given the high mortality rates associated with ALF, healthcare providers should be aware of the broad range of viral infections that have been implicated to enable early diagnosis, rapid treatment initiation when possible, and optimal management, which may include liver transplantation. This review aims to provide a summary of viral causes of ALF, diagnostic approaches, treatment options, and expected outcomes.

Hepatitis A virus infection

Hepatitis A is a vaccine-preventable infection caused by the hepatitis A virus (HAV). Over 150 million new infections of hepatitis A occur annually. HAV causes an acute inflammatory reaction in the liver that usually resolves spontaneously without chronic sequelae. However, up to 20% of patients experience a prolonged or relapsed course and <1% experience acute liver failure. Host factors, such as immunological status, age, pregnancy and underlying hepatic diseases, can affect the severity of disease. Anti-HAV IgG antibodies produced in response to HAV infection persist for life and protect against re-infection; vaccine-induced antibodies against hepatitis A confer long-term protection. The WHO recommends vaccination for individuals at higher risk of infection and/or severe disease in countries with very low and low hepatitis A virus endemicity, and universal childhood vaccination in intermediate endemicity countries. To date, >25 countries worldwide have implemented such programmes, resulting in a reduction in the incidence of HAV infection. Improving hygiene and sanitation, rapid identification of outbreaks and fast and accurate intervention in outbreak control are essential to reducing HAV transmission.

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.

The Impact of an Inactivated Hepatitis A Vaccine with One Dose in Brazil: A Retrospective Time-Series

BACKGROUND

In 2014, a recommended one-dose of inactivated hepatitis A vaccine was included in the Brazilian National Immunization Program targeting children 12-24 months. This decision addressed the low to intermediate endemicity status of hepatitis A across Brazil and the high rate of infection in children and adolescents between 5 and 19 years old. The aim of the study was to conduct a time-series analysis on hepatitis A incidence across age groups and to assess the hepatitis A distribution throughout Brazilian geographic regions.

METHODS

An interrupted time-series analysis was performed to assess hepatitis A incidence rates before (2010-2013) and after (2015-2018) hepatitis A vaccine program implementation. The time-series analysis was stratified by age groups while a secondary analysis examined geographic distribution of hepatitis A cases.

RESULTS

Overall incidence of hepatitis A decreased from 3.19/100.000 in the pre-vaccine period to 0.87/100.000 (p = 0.022) post-vaccine introduction. Incidence rate reduction was higher among children aged 1-4 years old, with an annual reduction of 67.6% in the post-vaccination period against a 7.7% annual reduction in the pre-vaccination period (p < 0.001). Between 2015 and 2018, the vaccination program prevented 14,468 hepatitis A cases.

CONCLUSION

Our study highlighted the positive impact of a recommended one-dose inactivated hepatitis A vaccine for 1-4-years-old in controlling hepatitis A at national level.

Hepatitis A antibody persistence 8 and 10 years after 1-dose and 2-dose vaccination in children from Panama

BACKGROUND

Hepatitis A virus (HAV) remains a global public health concern, which is potentially growing in Latin America, due to an expected shift from high to intermediate endemicity levels. The use of HAV vaccines in pediatric national immunization programs (NIPs), either as a 2-dose or a 1-dose schedule, has been explored in Latin American countries; however, evidence demonstrating long-term protection in this population is limited in the region. We evaluated long-term antibody persistence following a 1-dose partial series and the recommended 2-dose schedule used in Panama's pediatric NIP.

METHODS

Two independent cross-sectional serological surveys were conducted at year 8 (Y8) and Y10 following vaccination under the NIP with 1 or 2 doses of an inactivated HAV vaccine (Havrix, GSK). Seropositivity (anti-HAV antibody concentration ≥ 15 mIU/mL) rates and antibody geometric mean concentrations (GMCs) were assessed at each serosurvey. Non-inferiority of 1 dose versus 2 doses was also explored.

RESULTS

This study (NCT02712359) included 600 and 599 children at Y8 and Y10 post-vaccination, respectively. Seropositivity rates were 74.3% (95% confidence interval [CI]: 69.0; 79.2) and 97.7% (95% CI: 95.3; 99.1) at Y8 and 71.9% (95% CI: 66.4; 76.9) and 96.3% (95% CI: 93.5; 98.2) at Y10, in the 1-dose and 2-dose groups, respectively. Antibody GMCs were lower in the 1-dose versus the 2-dose group in both surveys. Non-inferiority was not demonstrated since the lower limit of the 2-sided 95% CI for the between-group difference in seropositivity rates (1-dose minus 2-dose) was < -10%.

CONCLUSION

Anti-HAV antibody persistence was observed in lower percentages of children receiving 1 dose versus 2 doses of Havrix, at 8 and 10 years post-vaccination in Panama. Further investigations are needed to confirm antibody persistence and conclude on the protection afforded beyond 10 years in the pediatric population in Latin America.

Hepatitis A epidemiology in Latin American countries: a 2020 view from a systematic literature review

INTRODUCTION

The World Health Organization recommends vaccination against hepatitis A virus (HAV) for children aged 1 year and older in areas where endemicity has shifted from high to intermediate. There are no recent comprehensive reviews of the epidemiology of HAV infection in Latin America, but seroprevalence and socioeconomic data suggest that, with improved clean water and sanitation systems, countries are transitioning to intermediate endemicity.

AREAS COVERED

We conducted a systematic literature review of the epidemiology of HAV infection in 25 countries in the Latin American region, which included gray literature. We compiled data on HAV incidence and prevalence, including the identification of epidemiological changes observed in countries that established pediatric HAV vaccination programs.

EXPERT OPINION

We identified 59 relevant articles, including 34 peer-reviewed seroprevalence studies (12 recent studies from Brazil), three incidence studies, and six vaccine impact studies (three from Argentina). Based on the estimated age at midpoint of population immunity in each country, most have a high-intermediate, intermediate, or low-intermediate level of HAV endemicity, suggesting that national childhood immunization may be an appropriate disease prevention strategy. However, recent data were lacking for most countries. Improved data quality and continued epidemiological surveillance are required for this region.

Systematic review of the global epidemiology of viral-induced acute liver failure

OBJECTIVES

The aetiology and burden of viral-induced acute liver failure remains unclear globally. It is important to understand the epidemiology of viral-induced ALF to plan for clinical case management and case prevention.

PARTICIPANTS

This systematic review was conducted to synthesize data on the relative contribution of different viruses to the aetiology of viral-induced acute liver failure in an attempt to compile evidence that is currently missing in the field. EBSCOhost, PubMed, ScienceDirect, Scopus and Web of Science were searched for relevant literature published from 2009 to 2019. The initial search was run on 9 April 2019 and updated via PubMed on 30 September 2019 with no new eligible studies to include. Twenty-five eligible studies were included in the results of this review.

RESULTS

This systematic review estimated the burden of acute liver failure after infection with hepatitis B virus, hepatitis A virus, hepatitis C virus, hepatitis E virus, herpes simplex virus/human herpesvirus, cytomegalovirus, Epstein-Barr virus and parvovirus B19. Data were largely missing for acute liver failure after infection with varicella-zostervirus, human parainfluenza viruses, yellow fever virus, coxsackievirus and/or adenovirus. The prevalence of hepatitis A-induced acute liver failur was markedly lower in countries with routine hepatitis A immunisation versus no routine hepatitis A immunisation. Hepatitis E virus was the most common aetiological cause of viral-induced acute liver failure reported in this review. In addition, viral-induced acute liver failure had poor outcomes as indicated by high fatality rates, which appear to increase with poor economic status of the studied countries.

CONCLUSIONS

Immunisation against hepatitis A and hepatitis B should be prioritised in low-income and middle-income countries to prevent high viral-induced acute liver failure mortality rates, especially in settings where resources for managing acute liver failure are lacking. The expanded use of hepatitis E immunisation should be explored as hepatitis E virus was the most common cause of acute liver failure.

REGISTRATION

PROSPERO registration number: CRD42017079730.

Changing Etiologies and Prognostic Factors in Pediatric Acute Liver Failure

After the implementation of universal hepatitis A virus vaccination in Argentina, the outcome of pediatric acute liver failure (PALF) remains unknown. We aimed to identify variables associated with the risk of liver transplantation (LT) or death and to determine the causes and short-term outcomes of PALF in Argentina. We retrospectively included 135 patients with PALF listed for LT between 2007 and 2016. Patients with autoimmune hepatitis (AIH), Wilson's disease (WD), or inborn errors of metabolism (IEM) were classified as PALF-chronic liver disease (CLD), and others were classified as "pure" PALF. A logistic regression model was developed to identify factors independently associated with death or need of LT and risk stratification. The most common etiologies were indeterminate (52%), AIH (23%), WD (6%), and IEM (6%). Overall, transplant-free survival was 35%, whereas 50% of the patients underwent LT and 15% died on the waiting list. The 3-month risk of LT or death was significantly higher among patients with pure PALF compared with PALF-CLD (76.5% versus 42.5%; relative risk, 1.8 [1.3-2.5]; P < 0.001), and 3 risk factors were independently associated with worse outcome: international normalized ratio (INR) ≥3.5 (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.3-7.2]), bilirubin ≥17 mg/dL (OR, 4.4; 95% CI, 1.9-10.3]), and pure PALF (OR, 3.8; 95% CI, 1.6-8.9). Patients were identified by the number of risk factors: Patients with 0, 1, or ≥2 risk factors presented a 3-month risk of worse outcome of 17.6%, 36.6%, and 82%, respectively. In conclusion, although lacking external validation, this simple risk-staging model might help stratify patients with different transplant-free survival rates and may contribute to establishing the optimal timing for LT.

The global epidemiology of viral-induced acute liver failure: a systematic review protocol

INTRODUCTION

The burden of viral-induced acute liver failure (ALF) around the world still remains unclear, with little to no data collected regarding the disease incidence in general and synthesised data on the relative contribution of different viruses to the aetiology of ALF is missing in the field. The aim of this review is to estimate the burden (prevalence, incidence, mortality, hospitalisation) of ALF following infection HAV, HBV, HCV, HDV, HEV, EBV), HSV1, HSV2, VZV, parvo-virus B19, HPIVs, YFV, HVV-6, CMV, CA16 and/or HAdVs. Establishing the common aetiologies of viral-induced ALF, which vary geographically, is important so that: (1) treatment can be initiated quickly, (2) contraindications to liver transplant can be identified, (3) prognoses can be deterined more accurately, and most importantly, (4) vaccination against viral ALF aetiologies can be prioritised especially in under-resourced regions with public health risks associated with the relevant attributable diseases.

METHODS AND ANALYSIS

EBSCOhost, PubMed, ScienceDirect, Scopus and Web of Science databases will be searched for relevant literature published and grey literature from 2009 up to 2019. Published cross-sectional and cohort studies will be eligible for inclusion in this review. Qualifying studies will be formally assessed for quality and risk of bias using a standardised scoring tool. Following standardised data extraction, meta-analyses will be carried out using STATA. Depending on characteristics of included studies, subgroup analyses and meta-regression analyses will be performed. This review will be reported according to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines.

ETHICS AND DISSEMINATION

No ethics approval is required as the systematic review will use only published data already in the public domain. Findings will be disseminated through publication in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42018110309.

Fulminant acute hepatitis in pediatrics in Latin America and the Caribbean

SUMMARY OBJECTIVE: The objective of this review was to investigate the epidemiology of Fulminant Acute Hepatitis in Latin America and the Caribbean and identify possible measures aimed at a better understanding and improvement of patient support. METHODS: We used 3 different researchers to investigate the topic of Fulminant Acute Hepatitis in pediatrics in papers published by Latin American and Caribbean authors in the PubMed and SciELO databases from 2000 to 2016. RESULTS: We found 2,879 articles in the databases searched. After selecting and excluding articles according to the study protocol, 68 remaining studies were obtained for analysis. A total of 1,265 cases of acute fulminant hepatitis were detected, with a predominance of females (42.9%), followed by males (39.4%), with no description of sex in 17.7% of the cases. The main cause was viral hepatitis, representing 45.1% of the cases. The hepatitis A virus was responsible for 34.7% of the total cases and 76.9% of the infectious causes. Of the total number of patients, 26.9% were described as idiopathic, and 11.5% had no cause. CONCLUSION: The preventable causes of Fulminant Acute Hepatitis include hepatitis viruses - primarily the hepatitis A virus - and poisoning. Active vaccination, basic sanitation, and public awareness can reduce the number of patients and, consequently, the costs of liver transplantation due to these causes.

Emerging Threat: Changing Epidemiology of Hepatitis A and Acute Kidney Injury

In the past decade, hepatitis A has been considered a rare disease in the United States, largely due to targeted vaccination of at-risk children. Evolving epidemiology has resulted in decreasing immunity and increasing hepatitis A infections among adults who are more likely to experience severe disease. A surge in outbreaks has been noted in the past 2 years, resulting in a high volume of hepatitis A related hospitalizations and complications in otherwise healthy individuals. The traditional understanding that acute kidney injury is a rare extrahepatic manifestation is being challenged by the resurgence of hepatitis A in a more vulnerable population. This review examines the epidemiologic factors that contributed to current public health concern and the association between hepatitis A and acute kidney injury.

Clinical experience with the inactivated hepatitis A vaccine, Avaxim 80U Pediatric

INTRODUCTION

Hepatitis A, caused by hepatitis A virus (HAV), is primarily transmitted via the fecal/oral route either through ingestion of contaminated food and water or through direct contact with an infectious person. Prevalence of hepatitis A is strongly correlated with socioeconomic factors, decreasing with increased socio-economic development, access to clean water and sanitation. Vaccination against HAV should be part of a comprehensive plan for the prevention and control of viral hepatitis, either as part of regular childhood immunization programs or with other recommended vaccines for travelers. Areas covered: We present here evidence for the immunogenicity and safety of an inactivated HAV pediatric vaccine (Avaxim® 80U Pediatric, Sanofi Pasteur), indicated for use in children aged 12 months to 15 years. Data evaluated are from trials undertaken during the clinical development of this vaccine, a systematic literature review and post-market pharmacovigilance. Expert opinion: The pediatric HAV vaccine is highly immunogenic and generates long-lasting protection against hepatitis A disease in children. The safety and immunogenicity data presented in this review suggest that the pediatric HAV vaccine is a valuable option in the prevention of HAV infection in children in many areas of the world where the disease remains a healthcare issue.

Public health impact and cost effectiveness of routine childhood vaccination for hepatitis a in Jordan: a dynamic model approach

Background

As the socioeconomic conditions in Jordan have improved over recent decades the disease and economic burden of Hepatitis A has increased. The purpose of this study is to assess the potential health and economic impact of a two-dose hepatitis A vaccine program covering one-year old children in Jordan.

Methods

We adapted an age-structured population model of hepatitis A transmission dynamics to project the epidemiologic and economic impact of vaccinating one-year old children for 50 years in Jordan. The epidemiologic model was calibrated using local data on hepatitis A in Jordan. These data included seroprevalence and incidence data from the Jordan Ministry of Health as well as hospitalization data from King Abdullah University Hospital in Irbid, Jordan. We assumed 90% of all children would be vaccinated with the two-dose regimen by two years of age. The economic evaluation adopted a societal perspective and measured benefits using the quality-adjusted life-year (QALY).

Results

The modeled vaccination program reduced the incidence of hepatitis A in Jordan by 99%, 50 years after its introduction. The model projected 4.26 million avoided hepatitis A infections, 1.42 million outpatient visits, 22,475 hospitalizations, 508 fulminant cases, 95 liver transplants, and 76 deaths over a 50 year time horizon. In addition, we found, over a 50 year time horizon, the vaccination program would gain 37,502 QALYs and save over $42.6 million in total costs. The vaccination program became cost-saving within 6 years of its introduction and was highly cost-effective during the first 5 years.

Conclusion

A vaccination program covering one-year old children is projected to be a cost-saving intervention that will significantly reduce the public health and economic burden of hepatitis A in Jordan.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3034-8) contains supplementary material, which is available to authorized users.

Type A viral hepatitis: A summary and update on the molecular virology, epidemiology, pathogenesis and prevention

Although epidemic jaundice was well known to physicians of antiquity, it is only in recent years that medical science has begun to unravel the origins of hepatitis A virus (HAV) and the unique pathobiology underlying acute hepatitis A in humans. Improvements in sanitation and the successful development of highly efficacious vaccines have markedly reduced the worldwide prevalence and incidence of this enterically-transmitted infection over the past quarter century, yet the virus persists in vulnerable populations and remains a common cause of food-borne disease outbreaks in economically-advantaged societies. Reductions in the prevalence of HAV have led to increases in the median age at which infection occurs, often resulting in more severe disease in affected persons and paradoxical increases in disease burden in some developing nations. Here, we summarize recent advances in the molecular virology of HAV, an atypical member of the Picornaviridae family, survey what is known of the pathogenesis of hepatitis A in humans and the host-pathogen interactions that typify the infection, and review medical and public health aspects of immunisation and disease prevention.

Single-dose Universal Hepatitis A Immunization in One-year-old Children in Argentina: High Prevalence of Protective Antibodies up to 9 Years After Vaccination

BACKGROUND

Single-dose hepatitis A virus (HAV) vaccination was implemented in all Argentinean children 12 months of age in 2005. Previous studies demonstrated high prevalence of protective antibody response 4 years after single-dose vaccination. This study assessed long-term seroprotection against HAV after vaccination.

METHODS

Children who received 1 dose of HAV vaccine at 1 year of age at least 6 years before enrollment were included at 5 centers in Argentina between 2013 and 2014. Demographic and socioeconomic characteristics were collected through a questionnaire. Blood samples were tested for anti-HAV antibodies. Antibody values ≥10 mIU/mL were considered seroprotective. Logistic regression analysis was performed to evaluate the association between demographic and socioeconomic variables and seroprotection.

RESULTS

A total of 1088 children were included, with a median postvaccination interval of 7.7 years (range 6.3-9.2 years). Of these children, 97.4% (95% confidence interval: 96.3%-98.3%) had protective antibodies against HAV. No association between demographic or socioeconomic variables and seroprotection was found. Geometric mean concentration of antibody levels against HAV was 170.5 mUI/mL (95% confidence interval: 163.2-178.2 mUI/mL).

CONCLUSIONS

Single-dose universal hepatitis A immunization in 1-year-old children resulted in sustained immunologic protection for up to 9 years in Argentina. These findings, along with the low current disease burden, confirm the success of the intervention.

The impact of assumptions regarding vaccine-induced immunity on the public health and cost-effectiveness of hepatitis A vaccination: Is one dose sufficient?

Hepatitis A vaccination stimulates memory cells to produce an anamnestic response. In this study, we used a mathematical model to examine how long-term immune memory might convey additional protection against clinical/icteric infections. Dynamic and decision models were used to estimate the expected number of cases, and the costs and quality-adjusted life-years (QALYs), respectively. Several scenarios were explored by assuming: (1) varying duration of vaccine-induced immune memory, (2) and/or varying levels of vaccine-induced immune memory protection (IMP), (3) and/or varying levels of infectiousness in vaccinated individuals with IMP. The base case analysis assumed a time horizon of 25 y (2012 - 2036), with additional analyses over 50 and 75 y. The analyses were conducted in the Mexican public health system perspective. In the base case that assumed no vaccine-induced IMP, the 2-dose hepatitis A vaccination strategy was cost-effective compared with the 1-dose strategy over the 3 time horizons. However, it was not cost-effective if we assumed additional IMP durations of at least 10 y in the 25-y horizon. In the 50- and 75-y horizons, the 2-dose strategy was always cost-effective, except when 100% reduction in the probability of icteric Infections, 75% reduction in infectiousness, and mean durations of IMP of at least 50 y were assumed. This analysis indicates that routine vaccination of toddlers against hepatitis A virus would be cost-effective in Mexico using a single-dose vaccination strategy. However, the cost-effectiveness of a second dose depends on the assumptions of additional protection by IMP and the time horizon over which the analysis is performed.

Pediatric liver transplantation in Latin America: Where do we stand?

LT started in LA in 1968, and pediatric LT records are available starting in the 1990s. Currently, eight countries perform pediatric LT in LA. Registries by national organizations fail to report robust data on pediatric LT. The aim of this paper was to report on the pediatric LT activity in LA. Data were gathered retrospectively through information available in the national registries websites and from local centers. Of the eight countries that report pediatric LT activity, Brazil, Argentina, Mexico, and Colombia have adequate registries of the numbers of LT performed. These countries concentrate most of the activity for pediatric LT. A total of 4593 pediatric LT were reported in LA. Websites for national organizations do not provide open data on post-transplant survival rates or waiting list mortality. The information herein is based on reports by local centers. Overall, survival from select centers is similar to that reported on North American and European registries, between 80 and 90% in the first year post-transplant. In conclusion, pediatric LT activity is growing in LA, especially in Brazil and Argentina. However, the lack of an appropriate LA registry restricts the assessment of quality and therefore restricts interventions aimed at quality improvements in different regions.

Hepatitis A: epidemiology in resource-poor countries

PURPOSE OF REVIEW

Transmission of hepatitis A virus (HAV) infection is primarily fecal-oral. Symptomatic hepatitis, severe disease, and death are more likely to occur when infection occurs at an older age. Improvements in socioeconomic and hygienic conditions have led to a change in its epidemiology worldwide.

RECENT FINDINGS

In the last two decades, improved hygiene in several resource-poor countries has led to reduced transmission of HAV, an increase in average age at infection, and, consequently, a paradoxical increase in morbidity and mortality because of hepatitis A. In Argentina, introduction of one dose (instead of the conventional two doses, to reduce costs) of inactivated HAV vaccine at 12-month age in a universal childhood immunization program during such 'epidemiologic transition' has markedly reduced the incidence of symptomatic hepatitis A, and of fulminant hepatitis and liver transplantation caused by HAV infection. The monetary value of medical and nonmedical benefits of this strategy outweighed the expenditure on vaccination. These excellent results were possibly contingent upon a high vaccination coverage.

SUMMARY

Resource-poor countries should closely monitor the epidemiology of HAV infection and periodically undertake cost-effectiveness analyses of HAV immunization strategies. This should allow timely identification of epidemiologic transition and introduction of preventive strategies before HAV infection becomes a public health problem.

Hepatotropic viruses as etiological agents of acute liver failure and related-outcomes among children in India: a retrospective hospital-based study

BACKGROUND

Acute liver failure (ALF) is marked by a sudden loss of hepatic function and is associated with a high mortality rate in children. The etiology of ALF is shown to vary geographically. This study assessed the frequency of hepatotropic viruses as etiological agents of ALF in Indian children.

METHODS

This retrospective study enrolled children aged 0-18 years with confirmed ALF admitted to Christian Medical College, Vellore and King Edward Memorial Hospital and Research Center, Pune between January 2003 and December 2005. The frequency of hepatotropic viruses as etiological agents in children with ALF aged ≤18 years was calculated with 95% confidence interval (CI). Descriptive analyses of demographic characteristics, clinical signs and symptoms of ALF, choice of treatment and outcomes were performed.

RESULTS

Of 76 children enrolled, 54 were included in the per-protocol analyses. Mean age of children with ALF was 5.43 years (standard deviation = 3.62); 51.9% (28/54) were female. The percentage of children positive for anti-hepatitis A virus (HAV) IgM and hepatitis B surface antigen was 65.9% (27/41; 95% CI 49.4-79.9) and 15.9% (7/44; 95% CI 6.6-30.1), respectively. The final cause of ALF was HAV (36.3%) followed by hepatitis B virus (HBV; 8.8%). Before and during admission, encephalopathy was observed in 77.8% (42/54) and 63.0% (34/54) of children, respectively. A high number of children (46/54; 85.2%) required intensive care and ALF was fatal in 24.1% (13/54). The proportion of deaths due to HAV and HBV was 18.5% (5/27) and 57.1% (4/7), respectively.

CONCLUSIONS

HAV and HBV were the most common etiological agents of ALF in Indian children. Primary prevention by vaccination against HAV and HBV in young children may be useful in the prevention of ALF due to viral hepatitis in India.

Results after the adoption of a MELD/PELD-based liver allocation policy in Argentina

In July 2005, Argentina switched from a categorical liver allocation system to a MELD/PELD-based policy for patients with CLD. To analyze WL outcomes and survival after LT in children. From January 2000 to December 2010, 923 children were registered. Two consecutive five-yr periods were analyzed and compared: Era I (January 2000-July 2005) (n = 379) and Era II (July 2005-December 31, 2010) (n = 544). All data were prospectively collected and analyzed using the Kaplan-Meier method. After adopting the MELD/PELD system, WL registrations increased by 44% (from 379 to 544) and the number of LT increased by only 24% (from 278 to 365). However, three-month WL mortality rate (32% to 18%, p < 0.0001, HR 2.002 CI 95% 1.5-2.8) decreased significantly. No significant differences were observed between Era 1 and II in one-yr post-LT survival (77.5% vs. 84.1%, p = 0.3053) and in acute re-LT rate (9% vs. 5%, p = 0.1746). Under the MELD/PELD-based allocation system in Argentina, mortality on the WL significantly decreased in children with CLD without affecting post-LT survival, although reduced access to LT was observed.

Changing etiologies and outcomes of acute liver failure: perspectives from 6 transplant centers in Argentina

There is significant geographic variation in the etiologies and prognoses of acute liver failure (ALF). The aims of the present study were to determine the causes and short-term outcomes of ALF in Argentina, to evaluate the performance of prognostic criteria, and to identify clinical prognostic factors of death. We performed a retrospective analysis of 154 adult patients with ALF who were admitted to 6 liver transplantation (LT) programs between June 2005 and December 2011. The most frequent causes of ALF were viral hepatitis B (46 patients or 30%), autoimmune hepatitis (AIH; 40 patients or 26%), and indeterminate causes (40 patients or 26%). No acetaminophen (ACM) overdose was reported. One hundred and twenty one patients (78%) were included on the waiting list, and LT was performed for 83 patients (54%). Overall survival rate is now corected to 73%. Multivariate logistic regression identified 2 independent variables associated with adverse outcomes on admission: a Model for End-Stage Liver Disease (MELD) score ≥ 29 and an encephalopathy grade ≥ 3. In a direct comparison using a receiving operating characteristic curve analysis, the MELD score [C statistic = 0.830, 95% confidence interval (CI) = 0.73-0.93] had better prognostic accuracy for predicting outcomes than the Clichy criteria (C statistic = 0.719, 95% CI = 0.58-0.85) or the King's College criteria (C statistic = 0.631, 95% CI = 0.49-0.77). In conclusion, hepatitis B and AIH were the most frequent causes of fulminant hepatic failure in our series, and no cases of ACM overdosing were identified. A MELD score ≥ 29 and an encephalopathy grade ≥ 3 at admission were associated with death. The MELD score at admission showed the highest prognostic accuracy.

Impact of the single-dose immunization strategy against hepatitis A in Argentina

BACKGROUND

After a country wide outbreak occurred during 2003-2004, 1 dose of hepatitis A vaccine was introduced into Argentinian regular immunization schedule for all children aged 12 months in June 2005. The aim of this study was to assess the impact of this novel intervention.

METHODS

A longitudinal analysis was done of hepatitis A virus (HAV) infection rates reported to the National Epidemiological Surveillance System from 2000 to 2011. Occurrence of fulminant hepatic failure (FHF) and liver transplantation cases up to 2011 were also assessed. Incidence rates and clinical impact were compared between pre- and postvaccination periods (2000-2002 vs. 2006-2011). Notification rates were also compared by age groups and geographical regions.

RESULTS

Since 2006, an abrupt decline was observed in HAV infection rates, as well as in FHF and liver transplantation cases. The mean incidence rate of 7.9/100,000 in the postvaccination period represents a reduction of 88.1% (P < 0.001) when compared with the prevaccination period. Neither FHF nor liver transplantation due to HAV infection were observed since March 2007. Decline in incidence rates was evident in all geographical regions and all age groups but was higher in the prevaccination most affected areas and in young children. Although an absolute decrease was observed for cases and rates in all age groups, since 2006, a higher proportion of cases was observed in people >14 years of age.

CONCLUSIONS

The single-dose vaccination strategy has been highly effective for controlling HAV infection in all age groups till now in Argentina. Long-term surveillance will be critical to document the sustained success of this unique intervention.

Single-dose administration of inactivated hepatitis A vaccination in the context of hepatitis A vaccine recommendations

OBJECTIVES

Our objective was to identify evidence on the protection achieved by single-dose use of inactivated hepatitis A vaccines in order to evaluate the potential of a flexible booster administration in the form of a second dose.

METHODS

A search was conducted for evidence on single-dose administration of inactivated hepatitis A vaccine and its potential impacts on long-term seropositivity rates. The main pharmaceutical vaccine manufacturer federations and the corresponding authors of manuscripts were approached for additional epidemiologic data. Correspondence was also sent to the Argentinean Ministry of Health.

RESULTS

We identified 15 data sources reporting on protection achieved by a single dose of inactivated hepatitis A vaccine. The consistent finding was that the immune and memory response to the booster dose, or post-booster geometric mean titer, was independent of the time since initial vaccination. The impact of the booster on seroprotection was the same across sexes and age-groups. The longest time interval between initial and booster dose was 10.67 years, indicating that booster doses can be highly immunogenic for up to 10.67 years after primary vaccination.

CONCLUSIONS

Protective anti-hepatitis A virus antibody levels after a single dose of inactivated hepatitis A vaccine can persist for almost 11 years and increase or reappear after booster vaccination. Further research on the vaccine doses needed to achieve long-term protection against hepatitis A infection is required.

Advances in hepatitis immunization (A, B, E): public health policy and novel vaccine delivery

PURPOSE OF REVIEW

This review offers an update on hepatitis A, B and E vaccines based on relevant literature published in 2011-2012. Hepatitis A and B vaccines have been commercially available for years; however, the development of the hepatitis E vaccine is still facing some challenges.

RECENT FINDINGS

Current scientific evidence shows that both hepatitis A and B vaccines confer long-term protection. These data supported the updated recommendations from the WHO on hepatitis A and B vaccines and the respective booster policy. In addition, a single-dose hepatitis A vaccination programme may be an option for some intermediate endemic countries, as far as the epidemiological situation is further monitored. Recent data illustrate the co-administration of hepatitis A with infant vaccines, as well as the interchangeability with other hepatitis A vaccines. Two genetically engineered hepatitis E vaccines are currently in development, showing more than 95% protective efficacy.

SUMMARY

Follow-up of vaccinated individuals confirms the long-term protection offered by the hepatitis A as well as hepatitis B vaccines. Data confirm the safety and immunogenicity profile of both vaccines, also when used in patient groups. The first data on the hepatitis E vaccine look promising, but questions on cross-protection, long-term efficacy and safety and immunogenicity in pregnant women and children less than 2 years remain unanswered.

Persistence of immunity from 1 year of age after one or two doses of hepatitis A vaccine given to children in Argentina

BACKGROUND

This study was done to determine the immunogenicity of a single dose of hepatitis A vaccine in children, providing needed clinical data on the flexibility of booster administration.

METHODS

Participants had received one dose of inactivated hepatitis A vaccine (Avaxim™ 80 U Pediatric) at 12-23 months of age or two doses of the same vaccine at 12 and 18 months of age prior to enrolment. Anti-hepatitis A antibody concentrations were measured at the first, second, and third year after vaccination. Suspected cases of hepatitis A in participant families were assessed and family socioeconomic data were collected.

RESULTS

A series of 546 participants were enrolled. Of 467 (85.5%) participants completing 3 years of follow-up, 365 had received a single vaccine dose and 94 had received two vaccine doses. Seropositivity (anti-HAV ≥ 10 mIU/mL) at 3 years was 99.7% after one dose and 100% after two doses. At one year, geometric mean concentrations were higher after two doses (1433.9 mIU/mL, 95% confidence interval [CI] 1108-1855) than one (209.7 mIU/mL, 95% CI 190.6-230.6). Geometric mean concentrations decreased in both groups during the study, but remained well above 10 mIU/mL through the third year. The geometric mean of 3-year to one-year anti-hepatitis A concentration ratios was 0.74 (95% CI 0.70-0.79) following one dose and 0.57 (95% CI 0.47-0.70) following two doses. The greatest decrease in geometric mean concentrations occurred during the third year, ie, 21.2% in the one-dose group and 40.8% in the two-dose group. Six participants became seronegative during follow-up and responded strongly to a booster dose. Anti-hepatitis A concentrations increased in 135 children (34.9%) in the second year and 50 (13.7%) in the third year; none lived in a family with a case of hepatitis A. Three confirmed cases of hepatitis A occurred in family members. Participants belonged to a middle-income, urban/suburban population with good sanitation facilities and water supplies.

CONCLUSION

A single dose of hepatitis A vaccine at 12-23 months of age resulted in hepatitis A seropositivity in all but one vaccinee after 3 years. Increased anti-hepatitis A serum concentrations suggested exposure to wild-type hepatitis A virus in this middle-class socioeconomic environment. Continuing surveillance is required to confirm the effectiveness of a single-dose hepatitis A vaccination; however, the results of the first three years are encouraging.