Antibody persistence six years after two doses of combined hepatitis A and B vaccine

Delaying the third dose of Japanese aluminum-free hepatitis A vaccine Aimmugen elicits effective immune responses against hepatitis A in adults

Inactivated aluminum-adsorbed hepatitis A vaccines such as Havrix, Vaqta, and Avaxim are commonly used worldwide. These vaccines are typically administered in a two-dose series (at 0 and 6-12 months). However, a lyophilized inactivated aluminum-free hepatitis A vaccine, Aimmugen, which is approved in Japan, is typically administered in a three-dose series (at 0, 2-4, and 24 weeks). Hence, individuals visiting endemic hepatitis A areas receive the primary two doses of Aimmugen before traveling and the third booster dose much later. It is currently uncertain whether boosting with a delayed third dose of Aimmugen is effective, or whether a new vaccination schedule should instead be initiated. Therefore, we investigated the anti-hepatitis-A viral immune response of adult travelers who received the third dose of Aimmugen more than 24 weeks after the first dose. Participants were vaccinated with the third dose of Aimmugen more than 2 years after the first two doses. Antibody titers were measured at Day 0 (prevaccination) and at 28-42 days after the third dose of Aimmugen. Twenty-nine adult participants were enrolled in the study (14 men and 15 women; mean age ± standard deviation age, 36.2 ± 8.1 years). The interval between the first two doses and the third dose was 3-14 years. The seroprotection rate (i.e., the percentage of participants with anti-hepatitis A virus antibody titers ≥ 10 mIU/mL) was 96.6 % (28/29) at Day 0 and increased to 100 % (29/29) at Days 28-42. Geometric mean concentration increased from 105 to 4,013 mIU/mL. We demonstrated that delaying the third dose of Aimmugen still elicited effective immune responses after priming with two doses of the vaccine. Trial registration: UMIN Clinical Trials Registry (UMIN-CTR): MIN000013624. Registered 03 April 2014. https://center6.umin.ac.jp/cgi-bin/ctr/ctr_view_reg.cgi?recptno=R000015906.

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.

Rapid immunization effects of a new type of 60 μg hepatitis B vaccine compared with traditional 20 μg hepatitis B vaccines in adults

BACKGROUND

The widely recommended standard schedule of hepatitis B vaccine for adults is months 0, 1 and 6, which takes 6 months to complete. Rapid completion of one vaccination schedule is important to adults because of its low compliance with follow-up doses. A new type of 60 μg Hepatitis B vaccine, made by Shenzhen Kangtai Biological Products Co., LTD., is originally recommended for low or non-responders. The objective of this clinical trial was to test whether this 60 μg hepatitis B vaccine could be used in primary immune population and what is its level of immunogenicity and safety compared with other hepatitis B vaccines.

METHODS

This is a 2-center randomized controlled study. A total of 1169 healthy adults aged between 25 and 55 who tested negative for HBsAg, anti-HBs, and anti-HBc were eligible for the study and were enrolled from relatively fixed and stable sites, such as villages, schools and large enterprises et al in Xuanhua county in Hebei province and Huaibei county in Anhui province. They were randomized to group A (20 μg Engerix-B® with 0, 1, 6 month intervals), group B (20 μg Kangtai hepatitis B vaccine with 0, 1, 6 month intervals), group C (60 μg Kangtai hepatitis B vaccine with 0, 2 month intervals) and group D (20 μg Huabei hepatitis B vaccine made by recombinant DNA techniques in CHO cell with 0, 1, 6 month intervals). In group A, B and D, every study object's blood sample was collected in the second month after their final injection to test the anti-HBs levels; while in group C, the blood sample was collected in the second month after the first and the second injection to test the anti-HBs levels. Adverse events were collected after each dose to assess the vaccines' safety.

RESULTS

The seroprotection rates were 93.17%, 97.23%, 93.54% and 98.98% respectively and the geometric mean titers (GMTs) were 1033.38 mIU/ml, 600.75 mIU/ml, 265.69 mIU/ml and 1627.05 mIU/ml in group A,B,C and D respectively. The difference of seroprotection rate among the 4 groups was statistically significant (χ² = 17.26, P<0.05). The difference of titers of anti-HBs among the 4 groups was statistically significant (H = 162.42, P<0.05). BMI, age (older than 40) and smoking were the influence factors of anti-HBs levels on 60 μg hepatitis B vaccine.

CONCLUSION

60 μg hepatitis B vaccine has a satisfactory safety and seroprotection rate in adult, It could be used in rapid adult hepatitis B immunization.

Immunogenicity and estimation of antibody persistence following vaccination with an inactivated virosomal hepatitis A vaccine in adults: A 20-year follow-up study

PURPOSE

This was a 20-year follow-up study to assess long-term persistence of protective antibody levels against the hepatitis A virus (HAV) in healthy participants vaccinated with 2 doses of inactivated hepatitis A vaccine (Epaxal®) between 1992 and 1995.

METHODS

Blood samples for anti-HAV antibody concentrations were obtained during a follow-up visit 20years after vaccination and were analyzed in parallel with samples still available from previous visits using AxSYM® HAVAB 2.0 assay.

RESULTS

Mean (SD) age of the participants was 44.71 (3.905) years at year 20 follow-up (N=95). Participants completing 0/12-month Epaxal® immunization regimen (N=94) had seroprotection rate of 100% (95% CI: 96.2, 100.0) with ⩾10mIU/mL seropositivity cut-off and 98.9% (95% CI: 94.2, 100.0) with ⩾20mIU/mL cut-off. With ⩾10mIU/mL cut-off, the estimated median duration of protection was 77.3years (95% CI: 71.8, 83.5) with 95% of the vaccinated participants predicted to be protected for at least 41.5years. At ⩾20mIU/mL cut-off, the estimated median duration of protection was 64.8years (95% CI: 60.1, 68.4) with 95% of the vaccinated participants predicted to be protected for at least 33years. Anti-HAV antibody geometric mean concentrations were higher in women (277.9; 95% CI: 217.7, 354.7) than in men (167.7; 95% CI: 125.2, 224.6).

CONCLUSION

The data from this 20-year follow-up study confirm previous observations that two doses of Epaxal® provide protection against hepatitis A infection for at least 30years in over 95% of healthy participants.

Hepatitis B Seroprotection and the Response to a Challenging Dose among Vaccinated Children in Red Sea Governorate

AIM:

To assess the long-term effectiveness of hepatitis B virus vaccine and the need for a booster dose among children who received three doses of vaccine during infancy in Red Sea Governorate.

METHODS:

A cross-sectional study was performed. Interviews with children (9 months to 16 years) and parents were done. Blood samples to assess Hepatitis B markers were tested. Children showing no seroprotection received a booster dose to assess their anamnestic response after four weeks and one year later.

RESULTS:

None of the participants had evidence of chronic Hepatitis B. The seroprotection rate was 23.3% and it significantly decreased with age. Multivariate logistic analysis revealed that older age was the significant predicting variable for having no seroprotective level, while baseline anti-HBs level < 3.3 IU/L was the predicting variable for not developing early anamnestic response or loss of late anamnestic response.

CONCLUSION:

Long-term immunity persists among children who received complete series of hepatitis B vaccination during infancy even in absence or reduction of anti-HBs over time. Therefore, a booster dose is not necessary to maintain immunity till the age of sixteen.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Safety and immunogenicity of different two-dose regimens of an investigational hepatitis B vaccine (hepatitis B surface antigen co-administered with an immunostimulatory phosphorothioate oligodeoxyribonucleotide) in healthy young adults

BACKGROUND

Previous studies have shown that two doses of an investigational hepatitis B vaccine consisting of hepatitis B surface antigen combined with an immunostimulatory phosphorothioate oligodeoxyribonucleotide adjuvant (HBV-ISS) given 8 weeks apart provides seroprotection sooner than 3 doses of a licensed hepatitis B vaccine over 24 weeks. A more rapid schedule with a 4-week interval could provide earlier protection and potentially greater compliance.

METHODS

In this randomized, double-blind study, healthy adults received two doses of HBV-ISS at 0 and 4 or 0 and 8 weeks; saline placebo was given at week 8 for the 0-4 schedule and at week 4 for the 0-8 schedule). Adverse events were collected after each dose. Antibodies were measured at 0, 4, 8, 12, and 32 weeks.

RESULTS

Participants were randomized to the 0-4 (n=18) or 0-8 (n=23) weeks schedule. Rates of adverse events were similar in the two groups after the HBV-ISS injections regardless of the schedule, but more frequent than after the placebo injections. By 4 weeks post-dose-2, 94.1% of 0-4 and 100% of 0-8 recipients had protective antibody levels; geometric mean concentrations were 244 mIU/mL and 3217 mIU/mL respectively. By 32 weeks, the difference in antibody concentration had decreased (GMC 439 mIU/mL vs. 863 mIU/mL, respectively; p=0.04).

CONCLUSIONS

A 0-4 weeks, two-dose regimen of HBV-ISS was well-tolerated and induced an antibody response that was similar to a 0-8 weeks schedule.

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

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

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

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

Hepatitis A Virus among Drug Users and the Role of Vaccination: A Review

In countries with advanced economies better health and hygiene conditions, along with the introduction, in some cases, of global vaccination, have relegated most viral hepatitis to marginal social groups and, in particular, drug users (DUs). The availability of safe and effective vaccines for hepatitis A virus (HAV) and B (HBV) may play a major role in combating this phenomenon. Despite the availability of a safe and effective vaccine for over a decade and the recommendations of international health organizations, vaccinations against HAV among DUs are not as widely known and available as are HBV vaccinations. The purpose of this review article is to present the most significant data in the literature on the prevalence of HAV among DUs and the role of targeted vaccination. To our knowledge, the present article is the first to solely deal with vaccination against HAV in DUs. Immunization after the administration of anti-HAV vaccine has been demonstrated in DUs even if they have responded significantly less than either the general population or carriers of chronic liver disease. All the vaccines were well tolerated and adherence to the vaccine schedule was good. Further studies are needed to optimize the timing and doses of vaccine to be administered to DUs, especially to assess adherence and antibody persistence. Vaccination campaigns are feasible among DUs and have proven to be highly cost-effective.