Reactogenicity and immunogenicity of three different lots of a hepatitis A vaccine

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This review is withdrawn because it is outdated.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.

Immunogenicity and safety of three consecutive lots of a new preservative-free inactivated hepatitis A vaccine (Healive): a double-blind, randomized and controlled trial

Immunization is considered as the most effective way for the prophylaxis of hepatitis A virus (HAV) infection. This study aimed to evaluate the immunogenicity and safety of three consecutive lots of a new preservative-free inactivated hepatitis A vaccine (Healive) in healthy children. A double-blind, randomized and controlled clinical trial was conducted in healthy volunteers aged from 1 to 8 years. Total 400 subjects were enrolled and assigned into four groups, receiving one of the three lots of Healive or an established control vaccine. The vaccination was two-dose regimen with 6 months apart. Anti-HAV titers were determined at the 1st, 6th and 7th month. The results showed that Healive was highly immunogenic in children with 100% seroconversion rate (SR) and 3237-3814 mIU/ml geometry mean titer (GMT) 1 month after the second dose. The immunogenicity of Healive was statistically higher than that of the control vaccine with respect to GMT and SR (P=0.037 to P<0.001). Both Healive and control vaccine were well tolerated with 1-5% incidence of overall adverse reactions (P>0.298). Severe adverse reaction was not reported. Both SRs (1, 6 and 7 months) and GMTs (1 and 7 months) in subjects receiving one of the three consecutive lots of Healive had not statistical difference (P=0.114-0.710), suggesting that Healive was well consistent. The immune responses in younger children (1-3 years) and older children (4-8 years) were similar to each other (P=0.187-0.963). The present study indicated that Healive was greatly consistent between production lots, well tolerated and highly immunogenic in children, which made the preservative-free inactivated hepatitis A vaccine well suitable for inclusion in the routine programme of children vaccination.

Dose range evaluation of a new inactivated hepatitis A vaccine administered as a single dose followed by a booster

A total of 242 healthy adults were immunised with a first dose of an investigational inactivated hepatitis A vaccine. Three concentrations (3, 6 and 12 EU [ELISA units]) of the experimental vaccine were used and compared to a licensed reference vaccine. The aim was to determine the antigenic concentration of the study vaccine inducing the highest seroconversion rate and anti-Hepatitis A virus (HAV) antibody response at 2 weeks after the primary immunisation. A booster dose was given at month 6. At 15 days after the primary immunisation the seroconversion rates in subjects vaccinated with the 6 and 12 EU vaccines were 78 and 94%, respectively. At 30 and 180 days after the primary immunisation the percentages of seropositivity were 100% for both groups. The antibody response to the 12 EU study vaccine was similar to that to the reference vaccine. The percentages of seropositivity at 15 and 180 days after the primary immunisation were 94 vs 93%, and 100 vs 93% in the experimental and reference vaccine respectively. Thus, because it induces early and lasting seroconversion, the 12 EU study vaccine seems to be the most effective as a high potency HAV vaccine.

Hepatitis A in urban Ireland

AIMS

To determine the prevalence of immunity to hepatitis A virus (HAV) infection in urban Ireland and to categorize the region into low, intermediate or high HAV endemicity, and to analyse the significance of certain commonly associated risk factors.

METHODS

Two hundred and thirty three volunteers were recruited from 6 general practices in Dublin, Ireland. There were 44 volunteers in the 10 to 19 yr age group, 40 in the 20 to 29, 42 in the 30 to 39, 43 in the 40 to 49 and 64 in the over 50 age groups. Each participant completed a detailed questionnaire and was tested for anti-HAV total antibody (primarily IgG) using a competitive ELISA assay. Urban Ireland was classified into the appropriate area of HAV endemicity according to the prevalence of immunity by age group. Risk factor differences were analysed for significance using the chi square test and Fisher's exact test.

RESULTS

One hundred and fifty seven (67 per cent) volunteers were immune, of whom 20 (45 per cent) were in the 10 to 19 yr age group, 17 (43 per cent) in the 20 to 29, 30 (71 per cent) in the 30 to 39, 34 (79 per cent) in the 40 to 49 and 59 (92 per cent) in the over 50 age groups. Fifty-five per cent of the individuals studied below the age of 20 yr were non-immune. The immune rates over the age of 30 were significantly greater (p < 0.01) than those in the 10 to 29 age groups. Socioeconomic pattern in the total and 10 to 19 yr age group was a significant (p < 0.0002, p < 0.004 respectively) risk factor for infection.

CONCLUSION

This study concludes that urban Ireland is an area of low HAV endemicity with age and socioeconomic status as the significant influences on seropositivity. This survey provides an insight into the changing epidemiology of HAV infection in Ireland and serves as a guide for immunisation of at risk population groups.

Clinical immunogenicity and tolerance studies of liquid vaccines delivered by jet-injector and a new single-use cartridge (Imule): comparison with standard syringe injection. Imule Investigators Group

A new needleless jet-injector, Mini-Imojet, was developed that administers liquid vaccines from a single-use, pre-filled cartridge named Imule, which avoids the risk of cross-contamination. We conducted clinical trials in several settings in France and West Africa to compare the immunogenicity and tolerance of five vaccines (influenza vaccine, Vi capsular polysaccharide typhoid vaccine, tetanus toxoid vaccine, diphtheria-tetanus-whole cell pertussis vaccine, and inactivated hepatitis A vaccine) administered with the Imule system vs standard syringe technique. In each vaccine study, all subjects of either group were tested for serum antibody titres to calculate the geometrical mean titres and seroconversion rates after complete vaccination. Immediate local-reactions were noted after each injection, and local and general reactions were evaluated during a predetermined period of follow-up. When delivered by the Imule technique, all the administered vaccines were of equivalent or superior immunogenicity, compared to the syringe technique. The tolerance to vaccines injected by the Imule system was acceptable in all studies. The most frequently observed reactions were mild (e.g. minor bleeding, superficial papules, erythema and induration) and could be considered to be inherent to the injection technique. The technical and safety advantages of the Mini-Imojet/Imule system, compared to sterilizable, standard disposable or autodestruct syringes and to classical multi-dose vial jet-injectors, reinforces the interest of this new injection technique for collective immunizations.

Immunogenicity and safety of a new inactivated hepatitis A vaccine in a comparative study

A multicentre, controlled, randomised, open, comparative trial including 839 healthy adult volunteers was carried out in order to compare the immunogenicity and reactogenicity of two vaccines against hepatitis A virus (HAV) during primary immunization and after booster injection. The first vaccine was produced by Pasteur Mérieux (PM), and the second vaccine by Smith-Kline Beecham (SKB). The vaccination schedule consisted of 2 doses (months 0, 6) for PM and 3 doses (months 0, 1, and 6) for SKB. Two weeks after the first dose, the seroconversion rates among initially HAV seronegative subjects (n = 608) were 93.4% and 76.1% for the PM and SKB vaccines, respectively, the corresponding geometric mean titres (GMTs) were 59.0 mIU/ml versus 30.8 mlU/ml (modified RIA HAVAB assay, Abbott Laboratories). Two months after the beginning of immunization (one dose versus two doses) the GMTs were 138.4 and 161.6 mlU/ml, respectively. At month 7, the seroconversion rates were 100% for both vaccines, and the GMTs were 4,189 and 3,163 mlU/ml, respectively. After the first dose of vaccine, 24.6% and 19.6% of the PM and SKB vaccines reported local reactions. The rates for systemic reactions were 27.2% and 25.0%, respectively. Lower rates for local and systemic reactions were seen after booster injections and statistical differences were not observed between the two vaccines. The study also demonstrated that vaccination was as well tolerated in subjects with anti-HAV antibodies as in HAV seronegative subjects. Logistic regression analysis revealed a significant vaccine effect on seroconversion rates only at week 2 (P < 10(-4). The same conclusions were drawn from the analysis of GMT by multivariate regression.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis A vaccine. A new convenient single-dose schedule with booster when long-term immunization is warranted

A total of 162 anti-HAV-negative healthy adults were immunized with a single high dose (1440 ELISA units = 1 ml) of inactivated hepatitis A vaccine and a booster was given at month 6. Antibodies were measured after modification of a commercial ELISA kit, enabling quantification of titres down to 6 mIU ml-1. After 14 days, 96% of vaccinees had positive anti-HAV titres (> 20 mIU ml-1), and after 30 days all vaccinees had seroconverted. The geometric mean titres were 150 mIU ml-1 and 380 mIU ml-1 respectively. The booster dose at month 6 elicited a dramatic (25-fold) increase in antibody titres from 125 to 3090 mIU ml-1. Thus a single dose may be a convenient alternative to immunoglobulin for inducing rapid seroprotection, with a booster dose at month 6 ensuring long-lasting protection.