Safety and Immunogenicity of a High-Potency Inactivated Hepatitis A Vaccine

Safety and immunogenicity of inactivated hepatitis-A vaccine developed by Human Biologicals Institute in two age groups of healthy subjects: A phase I open label study

BACKGROUND

Hepatitis-A is an acute viral infection of the liver. Hepatitis-A virus has worldwide spread and is endemic in India. Though the disease is self-limiting in most cases, outbreaks are reported frequently from both developing and developed countries of the world. Severity and fatality occur more among infected symptomatic adults. The infection can be prevented with proper and timely immunization. This phase I, single arm, open label, multicenter trial was designed to assess the safety and immunogenicity of the inactivated hepatitis-A vaccine developed by Human Biologicals Institute when administered in a single dose in two age groups of healthy subjects.

METHODS

This study was carried out in 55 subjects in two healthy age groups at two centers in India. Group A included subjects of 19-49 years and group B subjects of 12-18 years of age. Enrolled subjects received a single dose of inactivated hepatitis A vaccine. Blood samples were collected at baseline and 4-6 weeks after vaccination. Safety was assessed by collection and analysis of data on solicited and unsolicited adverse events and immunogenicity was assessed by estimating the seroconversion rate, seroprotection rate and the geometric mean titres of antibodies.

RESULTS

Among the 55 subjects enrolled, 15 reported adverse events. No serious adverse event was reported. Pain at the injection site was the lone local adverse event. Systemic adverse events reported in Group A were: fatigue, headache, diarrhoea, fever, anorexia, nausea and upper respiratory tract infection, whereas there was no systemic event reported in Group B. There was 100% seroconversion and seroprotection and significant rise in antibody titre levels were observed in both the groups post vaccination.

CONCLUSIONS

This study found HBI inactivated hepatitis-A vaccine to be safe and highly immunogenic when administered as a single dose in adolescent and adult subjects.

Hepatitis A immunisation in persons not previously exposed to hepatitis A

This review is withdrawn because it is outdated.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

Hepatitis 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.

The Seroconversion Rate of Hepatitis A Virus Vaccination among Patients with Hepatitis B Virus-Related Chronic Liver Disease in Korea

BACKGROUND/AIMS

The aim of this study was to evaluate the seroconversion rate of a hepatitis A virus (HAV) vaccination in patients with hepatitis B virus (HBV)-related chronic liver disease (CLD).

METHODS

Analyses were conducted using clinical records from 94 patients with chronic HBV infection who were seronegative for IgG anti-HAV antibodies between September 2008 and June 2009. Two doses of an HAV vaccine were administered 24 weeks apart. A third vaccine dose was administered only for patients seronegative for anti-HAV antibodies at week 48.

RESULTS

The seroconversion rate of anti-HAV following the two-dose vaccination was 86.17%. The seroconversion rate of anti-HAV was not significantly different according to age or status of liver disease. The rate was higher in female than in male patients. A third HAV vaccine dose was administered to 13 patients seronegative for anti-HAV after the two-dose regimen, and 84.62% of these patients showed seroconversion at week 72.

CONCLUSIONS

HAV vaccination is effective in most Korean patients with HBV-related CLD, and it might be necessary to evaluate three-dose vaccination approach for non-responders to the conventional regimen to maximize the success of an HAV vaccination program.

Acute hepatitis A in a young returning traveler from Kenya despite immunization before departure

Aluminum-adsorbed hepatitis A vaccines are known to be highly efficient. We present here the case of a patient who was immunized against hepatitis A before leaving for Kenya and who contracted an acute symptomatic hepatitis A during travel.

Long-term immunogenicity and protective efficacy of a live attenuated hepatitis A vaccine (LA-1 strain)

AIM

To evaluate the long-term protective efficacy following a large scale immunization with a live attenuated hepatitis A vaccine (the LA-1 strain) and immune persistence of the vaccine with different immunization schedules.

METHODS

A randomized controlled double-blind study was conducted in 212 985 children between 1.5 and 10 years of age from 8 counties in Guangxi province (10 0735 in vaccine group and 112 250 in control group). Vaccine group was received one dose of HAV vaccine of 10^6.75 TCID₅₀ (LA-1 strain, China). Surveillance of the incidence of hepatitis A in the two groups was started 1 month after vaccination. To evaluate the persistence of antibodies, 156 children of 6-9 years old with hepatitis A antibody negative were divided into 3 groups with equalities in age and sex. Group A was given one dose of the vaccine, Group B and C were immunized according to 0, 6 and 0, 12 schedules respectively. During follow-up of every individual, the blood specimens were collected at 6, 12, 24 and 36 months after immunization in Group A and 12, 24 and 36 months after first dose and 1 month after second dose in Group B and C. Anti-HAV levels were expressed as GMTs in mIU/ml by serial immunoglobulin dilutions (WHO standard) and HAVAB-Imx kit (Abbott Lab, USA).

RESULTS

During a follow-up for 36 months, 71 cases of symptomatic HAV infection were found in the control and 2 in the vaccine group (63.25/10⁶vs 1.99/10⁶ respectively). The protective efficacy was estimated at 96.85% with 95% lower confidence limit of 92.4%. The antibody positive rate in Group A after 6-24 months was 88.6-91.4%, the GMT was 105-106 mIU/ml, but each of those decreased to 80.0% and 99.20 mIU/ml after 36 months. GMT reached to the top in Group B and C1 month after the second dose, 1024.63 mIU/ml and 3 463.21 mIU/ml respectively. But during the time from top GMT to 24th month, the GMT of Group B and C decreased rapidly to about 59.4% and 83% respectively, and it continually declined slowly at 36^th month to 459.68 mIU/ml and 506.23 mIU/ml, which were 6% and 15% lower than that at 24^th month. It showed that the antibody level in Group B and C after 2 doses were significantly higher than that in Group A from beginning to end, at 36th month the GMT of Group B and C were 4.6 times and 5.1 times to that of Group A, and the antibody positive rate (97%) was higher than that of Group A (80%) at the same time.

CONCLUSION

A single dose of live attenuated hepatitis A vaccine can come into being high and persistent protection against hepatitis A. Booster dose induces an immune response which persists for at least three years in 97% of the subjects. The high GMT still present at month 36 predicts a long-term persistence of antibody.

Cost-benefit analysis of a nationwide infant immunization programme against hepatitis A in an area of intermediate endemicity

BACKGROUND/AIMS

The availability of safe and effective Hepatitis A vaccines prompts an evaluation of a nationwide infant vaccination campaign to supplement strategies aimed at high-risk groups such as travellers and military personnel.

METHODS

A spreadsheet model was used to estimate costs and benefits of a nationwide infant immunization programme against Hepatitis A for the period from 1997-2014 in Israel.

RESULTS

Immunizing all one year olds in Israel from 1997-2014 would for a cost of $32.0 million to the health services and $42.1 million to society (including $10.1 million lost work and transport costs), reduce the number of cases of Hepatitis A during the next 45 years from 181,000 to 47,000. This would save $57.5 million in health service resources alone, $32.0 million in averted work absences and transport costs in addition to a further $17.0 million in averted premature mortality costs. The health service, resource and societal benefit:cost ratios are 1.80:1, 2.13:1 and 2.54:1, respectively.

CONCLUSIONS

The recent adoption of a nationwide infant HAV immunisation policy in Israel is both medically and economically justifiable.

Inactivated hepatitis A vaccine in Chinese patients with chronic hepatitis B infection

BACKGROUND

Hepatitis B (HBV)-infected patients have a higher morbidity and mortality when super-infected by hepatitis A (HAV).

AIM

To evaluate the immunogenicity and safety of a commercial inactivated HAV vaccine in Chinese patients with chronic HBV infection.

METHODS

Sixty-five HBV-infected patients (30 carriers, 22 chronic hepatitis, 13 cirrhosis), who were seronegative for HAV, received a dose of 1440 ELISA units of HAV vaccine at weeks 0 and 24. Twenty-eight healthy individuals aged 18-57 years, who were seronegative for both HBV and HAV infection, also received the same vaccination regimen. Seroconversion was defined as an anti-HAV titre >/= 33 mIU/mL.

RESULTS

The seroconversion rates for the HBV-infected patients at weeks 2, 4 and 24 were 72, 91 and 80%, respectively. The corresponding geometric mean titres (GMTs) were 103, 311 and 123 mIU/mL. In the healthy control group the seroconversion rates were 86, 93 and 89% at weeks 2, 4 and 24. The corresponding GMTs were 112, 158 and 250 mIU/mL. There was no difference in the seroconversion rates between the two groups, but healthy controls had a significantly higher GMT at week 24 (P=0.04). Side-effects were more common in HBV patients.

CONCLUSION

The HAV vaccine is equally efficacious in patients with chronic HBV infection.

Comparison of two immunization schedules with an inactivated hepatitis A vaccine (AvaximTM)

BACKGROUND

Inactivated hepatitis A vaccines are licensed with a vaccination schedule based on two injections of vaccine given at least 6 months apart.

METHODS

Two vaccination schedules for the inactivated hepatitis A vaccine, AvaximTM (Pasteur Mérieux Connaught, Lyon, France), were compared in a monocentric, randomized, open trial. Two doses of the vaccine were given at intervals of either 6 months (0-6 month group) or 12 months (0-12 month group) to 96 adult volunteers. Anti-hepatitis A virus (HAV) antibody titers were determined in a blind fashion using the modified RIA (mRIA) HAVABtrade mark assay. After excluding subjects with positive preimmunization anti-HAV titers and those with protocol deviations, both groups were still comparable by sex ratio and mean age.

RESULTS

Four weeks (28 6 4 days) after the first dose, the seroconversion (SC) rate of initially HAV-seronegative subjects (antibody titer < 20 mIU/mL) was 100% in the 0-6 month group and 96. 9% in the 0-12 month group, with corresponding geometric mean titer (GMT) values (95% CI) of 369 mIU/mL (274-497 mIU/mL) and 445 mIU/mL (292-679 mIU/mL), respectively. After 6 months, SC was obtained in all subjects, and the corresponding GMT values were 349 mIU/mL and 359 mIU/mL in the 0-6 month group and the 0-12 month group, respectively. Four weeks after the booster dose given at 6 months, a 14.5-fold rise in GMT was observed. In the 0-12 month group, anti-HAV GMT values decreased by only 20% from 6 months to 12 months with a pre-booster GMT value of 286 mIU/mL at the 12-month evaluation. Four weeks after the booster given at 12 months, a 22. 5-fold rise in GMT was observed. Statistical analysis showed that the two vaccination schedules were comparable in their ability to boost antibody titers. Unsolicited reactions to vaccination were not different to those reported during earlier trials. Less than 12% of the vaccinees reported reactions after the first dose (11/93), or after the booster dose (11/92).

CONCLUSIONS

This trial demonstrated antibody persistence is excellent for at least 12 months after one dose of this vaccine, and that a booster may be given at any time between 6 and 12 months after primary immunization.