Concurrent administration of inactivated hepatitis A vaccine with immune globulin in healthy adults

Prevention of Hepatitis A Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices, 2020

HEPATITIS A IS A VACCINE-PREVENTABLE, COMMUNICABLE DISEASE OF THE LIVER CAUSED BY THE HEPATITIS A VIRUS (HAV). THE INFECTION IS TRANSMITTED VIA THE FECAL-ORAL ROUTE, USUALLY FROM DIRECT PERSON-TO-PERSON CONTACT OR CONSUMPTION OF CONTAMINATED FOOD OR WATER. HEPATITIS A IS AN ACUTE, SELF-LIMITED DISEASE THAT DOES NOT RESULT IN CHRONIC INFECTION. HAV ANTIBODIES (IMMUNOGLOBULIN G [IGG] ANTI-HAV) PRODUCED IN RESPONSE TO HAV INFECTION PERSIST FOR LIFE AND PROTECT AGAINST REINFECTION; IGG ANTI-HAV PRODUCED AFTER VACCINATION CONFER LONG-TERM IMMUNITY. THIS REPORT SUPPLANTS AND SUMMARIZES PREVIOUSLY PUBLISHED RECOMMENDATIONS FROM THE ADVISORY COMMITTEE ON IMMUNIZATION PRACTICES (ACIP) REGARDING THE PREVENTION OF HAV INFECTION IN THE UNITED STATES. ACIP RECOMMENDS ROUTINE VACCINATION OF CHILDREN AGED 12-23 MONTHS AND CATCH-UP VACCINATION FOR CHILDREN AND ADOLESCENTS AGED 2-18 YEARS WHO HAVE NOT PREVIOUSLY RECEIVED HEPATITIS A (HEPA) VACCINE AT ANY AGE. ACIP RECOMMENDS HEPA VACCINATION FOR ADULTS AT RISK FOR HAV INFECTION OR SEVERE DISEASE FROM HAV INFECTION AND FOR ADULTS REQUESTING PROTECTION AGAINST HAV WITHOUT ACKNOWLEDGMENT OF A RISK FACTOR. THESE RECOMMENDATIONS ALSO PROVIDE GUIDANCE FOR VACCINATION BEFORE TRAVEL, FOR POSTEXPOSURE PROPHYLAXIS, IN SETTINGS PROVIDING SERVICES TO ADULTS, AND DURING OUTBREAKS.

Hepatitis A immunisation in persons not previously exposed to hepatitis A

This review is withdrawn because it is outdated.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

Chemical Modification of Chitosan for Efficient Vaccine Delivery

Chitosan, which exhibits good biocompatibility, safety, microbial degradation and other excellent performances, has found application in all walks of life. In the field of medicine, usage of chitosan for the delivery of vaccine is favored by a wide range of researchers. However, due to its own natural limitations, its application has been constrained to the beginning of study. In order to improve the applicability for vaccine delivery, researchers have carried out various chemical modifications of chitosan. This review summarizes a variety of modification methods and applications of chitosan and its derivatives in the field of vaccine delivery.

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.

Hepatitis A immunisation in persons not previously exposed to hepatitis A

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Immunotherapy of viral infections

Among the microorganisms that cause diseases of medical or veterinary importance, the only group that is entirely dependent on the host, and hence not easily amenable to therapy via pharmaceuticals, is the viruses. Since viruses are obligate intracellular pathogens, and therefore depend a great deal on cellular processes, direct therapy of viral infections is difficult. Thus, modifying or targeting nonspecific or specific immune responses is an important aspect of intervention of ongoing viral infections. However, as a result of the unavailability of effective vaccines and the extended duration of manifestation, chronic viral infections are the most suitable for immunotherapies. We present an overview of various immunological strategies that have been applied for treating viral infections after exposure to the infectious agent.

Efficient neutralizing activity of cocktailed recombinant human antibodies against hepatitis A virus infection in vitro and in vivo

Hepatitis A virus (HAV) is the major pathogen responsible for acute infectious hepatitis A, a disease that is prevalent worldwide. Although HAV immunization effectively prevents infection, primary immunizations must be administered at least 2 weeks prior to HAV exposure. In contrast, passive immunization with pooled human immunoglobulin (Ig) can provide immediate and rapid protection from HAV infection. Because the use of human sera-derived Igs carries the risk of contamination, we sought to develop recombinant HAV-neutralizing human antibodies. We prepared a combinatorial phage display library of recombinant human anti-HAV antibodies from RNA extracted from the blood lymphocytes of a convalescent hepatitis A patient. Two recombinant human IgG antibodies, HAIgG16 and HAIgG78, were screened from the antibody library by their ability to bind with high affinity to purified, inactivated HAV virions. These antibodies recognized different epitopes of the HAV virion capsid, and competed with both patient sera and well-characterized neutralizing mouse monoclonal antibodies. A cocktailed mixture of HAIgG16 and HAIgG78 at a 3:1 ratio was prepared to compare its combined biological activity with that conferred by each antibody individually. The cocktailed antibodies displayed a stronger neutralizing activity in vitro than that observed with either HAIgG16 and HAIgG78 alone. To determine the in vivo neutralizing abilities of these antibodies, rhesus monkeys were inoculated with cocktailed antibodies and challenged with HAV. Whereas control animals developed hepatitis A and seroconverted to the HAV antibody, animals receiving cocktailed antibodies were protected either from viral infection or from developing clinical hepatitis. These results demonstrate that recombinant human antibody preparations could be used to prevent or treat early-stage HAV infection.

Prevention of hepatitis A by vaccination

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

The effectiveness and safety of hepatitis A vaccine: a systematic review

We report on the conduct of a systematic review to assess the efficacy and the safety of hepatitis A vaccines in adults and children. We identified, retrieved, and assessed all trials evaluating the effects of hepatitis A vaccines on prevention of cases of hepatitis A, death from hepatitis A, and assessing nature and frequency of adverse events. We included eight randomised trials, four containing efficacy outcomes, three containing only safety outcomes and a single study containing efficacy and adverse events outcomes. Combined inactivated vaccine effectiveness was 86% (95% CI: 63-95%). Combined attenuated vaccine effectiveness was 95% (95% CI: 81-99%). Inactivated vaccine effectiveness in the prevention of HAV secondary cases, compared to non-intervention was 82% (95% CI: 23-96%). Safety profile of vaccines was similar to that of their comparators. Despite poor design and reporting of trials, we found convincing evidence of the effectiveness and safety of inactivated HAV vaccines.

Hepatitis A vaccine

Hepatitis A is an infectious disease frequently reported in the United States. An average of 26,000 cases were reported each year during 1980 to 1999; probably 3 times as many occurred. Hepatitis A vaccines provide a powerful new prevention tool. The 2 inactivated hepatitis A vaccines available as pediatric and adult formulations in the United States and in many other countries are safe, immunogenic, and efficacious. A single dose provides excellent short-term protection; the second dose is thought to be important for long-term protection. Because hepatitis A virus (HAV) is excreted in high concentrations in the stool, the principal mode of transmission is person-to-person by the fecal-oral route, most commonly among household and sexual contacts of people with HAV infection. Children can be important in transmission because they frequently have unrecognized or asymptomatic infection. Implementation of recommendations for routine hepatitis A vaccination of children living in areas with consistently elevated hepatitis A rates appears to be resulting in dramatic declines in the overall incidence of the disease. Improved vaccination coverage and continued monitoring of incidence rates are needed to determine the overall long-term impact of this strategy.

Hepatitis vaccines

The development of highly effective and safe inactivated HAV vaccines and highly effective and safe recombinant HBsAg subunit HBV vaccines represents major advances in the control of viral hepatitis, but many challenges remain. Because current HAV immunization recommendations target high-risk groups only, infection rates are unlikely to fall dramatically until universal childhood immunization programs are implemented. Routine HBV vaccination of infants, children, adolescents, and individuals at high risk will reduce the incidence of infection, but vaccine nonresponsiveness and escape mutants are important potential challenges. Whether either HAV or HBV vaccine provide lifelong protection remains to be determined. Vaccines for HDV, HEV, and HCV are not yet available.

Hepatitis A vaccine

Inactivated hepatitis A vaccines are highly immunogenic and efficacious. Because of their high disease rates and importance as a reservoir of transmission to others, children should be the primary focus of vaccination. A long-term strategy of sustained routine vaccination of children living in areas with consistently elevated hepatitis A rates has been adopted. Ultimately, elimination of HAV transmission will require vaccination of all children in the US. This effort would be facilitated by the availability of vaccine formulations or schedules for use in infants or children in the second year of life, and combination vaccines that include hepatitis A.

Viral hepatitis. From prevention to antivirals

The challenge of viral hepatitis has been acknowledged and confronted in the last decade. Significant progress in prevention of infection with HAV and HBV may eradicate these serious infections from the United States and other parts of the world in the coming decades. Application of prophylactic strategies to children will be a major mechanism in accomplishing this task. The quest for potent antiviral medications continues. The next critically important development will be ways to prevent new HCV infections and to treat the millions of already infected individuals at risk for the serious consequences of this disease. For pediatricians, realizing these goals requires a greater understanding of perinatal HCV transmission, use of vaccines for prevention of viral hepatitis, and identification of HCV-infected children who are likely to benefit from new therapeutic strategies as they become available.

Viral hepatitis

Viral hepatitis accounts for most liver diseases seen in hepatology practice. In the past year studies have been focused on uncovering the basic mechanisms of viral-cellular interactions, the knowledge of which will contribute to more effective treatment. Hepatitis A virus outbreaks still occur, even in the most developed countries, which points to the need for more comprehensive vaccination measures. Lessons learned from the treatment of HIV with combination antiviral therapies are being applied to both chronic hepatitis B and C. Progress has been made toward better understanding of viral kinetics and the quasi-species of hepatitis C virus with new and more sensitive diagnostic methods. Several therapeutic protocols are emerging to identify and tailor the management approach in various subsets of the population. Although posttransplantation hepatitis B has been more effectively managed with lamivudine therapy, no major advances have been accomplished in the treatment of recurrent hepatitis C among transplant recipients. Major advances in the field of viral hepatitis including A to E and TT viruses during the past year are highlighted.

Design and analysis of three treatment equivalence trials

We consider design and analysis of clinical trials aimed at demonstrating equivalence of three treatments. We discuss analysis methods that require demonstrating that each pair of treatments has an unimportant difference. The critical values that we provide are smaller than the standard normal critical values, pointing out that the adjustment is counter to the usual multiplicity adjustments. Special issues in demonstrating equivalence of three rather than two treatments are discussed. We propose some conservative criteria for estimating sample size. Procedures for choosing pairs of treatments that are equivalent to each other, even when all three treatments are not shown equivalent, are also discussed along with implications for control of type I errors. We also demonstrate the methods with data from the literature.