Good immunogenicity of GBM strain inactivated hepatitis A vaccine in healthy male adults

Interchangeability of Hepatitis A boosters, Avaxim® and Vaqta®, in healthy adults following a primary dose of the combined typhoid/Hepatitis A vaccine Viatim®

This study investigated the suitability of Avaxim and Vaqta as Hepatitis A booster vaccines 6 months after priming with the combined Hepatitis A/typhoid vaccine, Viatim. One hundred and twenty adults were randomly assigned to one of the three groups. Group A (reference group) received Avaxim then Avaxim (n = 40), Group B received Viatim then Avaxim (n = 41) and Group C received Viatim then Vaqta (n = 39). One month after booster vaccination, anti-Hepatitis A virus (anti-HAV) antibodies geometric mean concentrations (GMC) of subjects primed with Viatim were non-inferior to the group primed and boosted with the monovalent Hepatitis A vaccine Avaxim. Anti-Salmonella typhi capsular polysaccharide virulence antigen (anti-Vi) GMCs in groups primed with Viatim were protective and all vaccines were well-tolerated. Therefore, Viatim may be used as a primary HAV vaccine with either Avaxim or Vaqta as Hepatitis A boosters and it will provide the same protection as two doses of Avaxim.

Hepatitis A vaccine in the last-minute traveler

Current recommendations state that travelers should receive hepatitis A vaccine 2 to 4 weeks before departure. Such recommendations, however, may dissuade last-minute travelers from receiving the vaccine. A preponderance of evidence exists to support hepatitis A vaccination of the imminent-departure traveler and therefore suggests that these guidelines merit reconsideration. In examining this issue, one of the most important elements to determine is the amount of time required for seroconversion following vaccination. Clinical trials of hepatitis A vaccines measured antibody response at 2 and 4 weeks after vaccination. However, studies investigating early seroconversion found that the vast majority of vaccinees develop antibodies within 2 weeks of vaccination, some as early as 12 days after vaccination. This is relevant information, given that the hepatitis A virus has an average incubation period of 28 days. Seroconversion is predicated on achieving a "protective" antibody level. However, levels of antibody considered protective remain debatable. Evidence suggests that clinical disease does not occur at antibody levels lower than those currently accepted as protective. Furthermore, hepatitis A vaccine has been proved effective in controlling outbreaks worldwide. Research data show that a single dose of vaccine can halt outbreaks if an adequate number of susceptible individuals are vaccinated. Information from rapid-outbreak control studies and those assessing postexposure administration of hepatitis A vaccine suggest that late vaccination provides a significant degree of protection. For these reasons, hepatitis A vaccine may be administered at any time before departure because it will still provide travelers with protection.

A randomized, open-label study of the immunogenicity and reactogenicity of three lots of a combined typhoid fever/hepatitis A vaccine in healthy adults

BACKGROUND

Travelers are often advised to receive both the typhoid fever and hepatitis A virus (HAV) vaccines, particularly when going to areas where the 2 diseases are endemic. Thus, combined administration of these vaccines could make immunization more acceptable by reducing the number of injections needed.

OBJECTIVE

This study compared the safety profiles and immunogenicity of 3 batches of a combined typhoid fever/HAV vaccine administered using a dual-chamber bypass syringe.

METHODS

This randomized, open-label study was conducted at 2 university-based travel clinics in Germany and Austria. Subjects received a single IM injection from 1 of 3 batches of the combined vaccine. Blood samples were drawn immediately before and 28 days after vaccination to evaluate the response to the 2 antigens by assessing geometric mean titers (GMTs) and rates of seroconversion and seroprotection. Subjects recorded all adverse events (AEs) occurring during the study period in a diary.

RESULTS

Six hundred ten healthy adults were enrolled in the study. Twenty-eight days after vaccination, 90.6% of the study population had protective typhoid Vi antibody titers (> or = 1 microg/mL) and 100% had protective HAV antibody titers (> or = 20 mIU/mL). Seroconversion rates and GMTs were not significantly different between the 3 batches. There were no differences with regard to local or systemic AEs between the 3 batches of vaccine. There were no immediate adverse reactions (within 30 minutes of vaccination) and no serious AEs related to vaccination. Of 609 evaluable subjects (1 was lost to follow-up after the first visit), 555 (91.1%) experienced > or = 1 local reaction within the first 7 days after vaccination, mainly pain at the injection site (550 [90.3%]), but only 26 (4.3%) described this pain as severe. Vaccine-related headache and mild to moderate asthenia were each reported by 54 subjects (8.9%). Symptoms resolved spontaneously in all cases.

CONCLUSIONS

The 3 batches of the combined typhoid fever/HAV vaccine administered by dual-chamber bypass syringe were equally well tolerated and effective in healthy adults, and did not differ significantly in terms of GMTs or seroconversion rates.

Vaccination options for last-minute travellers in need of travel-related prophylaxis against hepatitis A and B and typhoid fever: a practical guide

Last-minute travellers represent a particular challenge to travel healthcare professionals, as standard vaccination schedules can take a few months to complete. This has led researchers to investigate the value of alternative accelerated schedules and existing schedules among this group, particularly with respect to time taken for an individual to seroconvert, duration of protection and multiple vaccination requirements. This paper reviews the available options for the three most common vaccine preventable diseases among travellers-hepatitis A, hepatitis B and typhoid fever. Studies suggest that even if the first dose of hepatitis A vaccine is given on the day of travel, this will provide adequate protection, and that immunity to typhoid fever can be provided in over 70% of travellers following vaccination 1 week prior to departure. For hepatitis B, an accelerated schedule of 0, 7 and 21-days has been shown to induce early protection, and is considered to be of benefit to the last-minute traveller. Practical guidelines on vaccination options from one week up to one month, as well as one month or more prior to travel are presented. This should provide guidance for travel healthcare professionals, and reassure last-minute travellers that they need not begin their journey unprotected against these three serious infectious diseases.

Safety, immunogenicity and antibody persistence of an inactivated hepatitis A vaccine in 4 to 15 year old children

Among 277 healthy Venezuelan children, aged between 4 and 15 years, who were screened for hepatitis A virus (HAV) antibodies, 118 seronegative children were enrolled in an open study. Each child received one dose of the Pasteur Mérieux Connaught inactivated hepatitis A vaccine (AVAXIM¿trade mark omitted¿, 160 antigen units), followed by a booster dose 24 weeks later. All seronegative subjects seroconverted 2 weeks after immunisation (antibody titres greater, similar20 mIU/ml), and antibody titres were still over greater, similar20 mIU/ml after 24 weeks, at the moment of the booster dose. The anti-HAV antibody geometric mean titre (GMT), as measured by a modified radio-immunoassay (HAVAB(R), Abbott Laboratories, North Chicago, IL, USA), was 73.7 mIU/ml, 2 weeks after the first dose. Four weeks after the booster, the GMT value reached 6999 mIU/ml, representing a 29.6-fold rise from pre-booster levels. One year after the booster dose, the GMT value was 1673 mIU/ml in the 92 subjects who provided blood samples at this time, all of whom were still seroconverted ( greater, similar20 mIU/ml). No serious adverse event related to the vaccination occurred during the study. No immediate systemic reaction occurred. Local reactions were reported by 9.3% of subjects who received the primary injection and 5.5% of those given the booster dose. The systemic reactions were mainly fever and myalgia reported over the 7 days following the injection by 3.4% of subjects after the first dose and 5.5% of subjects after the booster dose. A clinically significant elevation of serum transaminase from pre-immunisation levels was noted in one subject (AST level 2.2 times the upper normal limit) 2 weeks after the first injection, although this was not associated with any clinical signs of impaired liver function. This trial demonstrated that AVAXIM¿trade mark omitted¿ containing 160 antigen units is safe and highly immunogenic in healthy children aged between 4 and 15 years, and could be included in the childhood vaccination schedule to control infection in areas endemic for hepatitis A.

Immunogenicity and reactogenicity of Avaxim (160 AU) as compared with Havrix (1440 EL.U) as a booster following primary immunization with Havrix (1440 EL.U) against hepatitis A

BACKGROUND

Hepatitis A vaccination is recommended for travelers from the UK to areas of moderate or high endemicity. Two licensed hepatitis A vaccines are now available in the UK, and this trial was undertaken to determine whether Avaxim can be used as a booster following a primary course of Havrix.

METHODS

One hundred and eighty-five subjects were randomized to receive a booster dose of either Avaxim (n=92) or Havrix (n=93), 6 to 7 months after a primary dose of Havrix. Subjects were observed for 30 minutes for immediate reactions and subsequently completed a diary card for a further 2 weeks. Serology samples for HAV antibody titers were taken at 28 6 7 days later.

RESULTS

One month following the booster dose, all subjects in both treatment groups achieved HAV antibody titers >= 20 mIU/mL. In the Avaxim group, geometric mean titer (GMT) values increased from 642 mIU/mL (97.5% CI 330-1250 mIU/mL) to 6669 mIU/mL (4566-9740 miu/mL), compared with 739 mIU/mL (379-1443 mIU/mL) at baseline to 4460 mIU/mL (2880-6908 mIU/mL) following the administration of Havrix. The increase in GMT following the administration of Avaxim was significantly greater than that following Havrix (p=.02). Eight percent of subjects reported pain at the injection site following a booster dose of Havrix, compared with none following Avaxim. This difference in reactogenicity was statistically significant (p=.01). In all other respects, both preparations were safe and equally well tolerated.

CONCLUSION

Either Avaxim or Havrix may be given as a booster dose of hepatitis A vaccine when Havrix has been administered as the primary dose.

Does immunoglobulin interfere with the immunogenicity to Pasteur Mérieux inactivated hepatitis A vaccine?

BACKGROUND/AIMS

The aim of this study was to compare the immunogenicity of Pasteur Mérieux (P.M. s.v.) inactivated hepatitis A vaccine when given alone with its immunogenicity when given in combination with immunoglobulin.

METHODS

We enrolled 80 healthy volunteers who were seronegative for anti-HAV. Forty subjects (group A) were given two doses of vaccine at 0 and 6 months plus 4 ml of immunoglobulin given simultaneously with the first vaccine injection; and 40 subjects (group B) were given vaccine alone. The population characteristics (age, sex, height and weight) of the two groups were comparable.

RESULTS

Anti-HAV antibody was detectable at week 1 in 100% of group A and in 5.7% of group B, and in 100% of both groups at 4 and 8 weeks. Seroconversion rates (> or = 20 mIU/ml) were 97.4% in group A and 100% in group B at week 24 and were 100% in both groups 4 weeks after a booster injection at 6 months. The antibody response level was lower after concomitant administration of vaccine with immunoglobulin. The antibody geometric mean titer was higher at week 1 in subjects who had been given vaccine and immunoglobulin, but nearly 50% lower at week 4 and thereafter, indicating inhibition of the vaccine-induced immune response by immunoglobulin. At week 28, i.e. 4 weeks after the booster injection, geometric mean titers had increased about 13-15 times in both groups, reaching highly protective antibody levels (3351 mIU/ml in group A and 5843 mIU/ml in group B). No serious adverse effects were observed during the follow-up.

CONCLUSIONS

These data indicate that P.M. s.v. hepatitis A vaccine is highly immunogenic and safe, even when given simultaneously with immunoglobulin. Despite the interference of the immunoglobulin with the active immune response, individuals who were immunized passively plus actively also developed high titers of anti-HAV antibody. It is therefore reasonable to expect that this inhibition will not affect the overall protection conferred by the vaccine.

Immunogenicity and efficacy of a killed hepatitis A vaccine in day care center children

The objective of this study was to characterize the immune response of children after the use of two different vaccine doses and to evaluate whether vaccination benefits children attending day care centers in areas with high anti-HAV seroprevalence. The study was conducted in a day care center with a stable population in São Paulo, Brazil. Two groups of 20 children, all seronegative for hepatitis A antibodies, were assigned randomly to receive three times 0.5 and 1.0 ml of the vaccine, the second and third dose 1 and 6 months after the first dose, respectively. There were 27 children in the control group. All children in both vaccinated groups had protective levels of antibodies in the serum after two inoculations, and serious adverse reactions were not observed. In the eighth month of follow-up, a hepatitis A outbreak occurred in the day care center. Five children in the control group had high titers of IgM class anti-HAV, four with clinical manifestations of acute hepatitis. None of the vaccinated children developed symptoms or signs of hepatitis (P = 0.0125), and the estimate of vaccine efficacy was 100%. Two nonstudy children from the center also had clinical and serological evidence of acute hepatitis A. It is concluded that vaccination represents an important method for prevention of hepatitis A transmission in day care centers. The results of this pilot study justify further testing in larger groups.

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)