Reappraisal of the Immunogenicity and Safety of Three Hepatitis A Vaccines in Adolescents

Although the overall incidence of hepatitis A in Korea has been decreasing, adolescents remain highly vulnerable to its outbreaks. This study was conducted to compare the immunogenicity and safety of three hepatitis A vaccines in Korean adolescents. Healthy anti-hepatitis A virus seronegative subjects aged 13 to 19 yr were randomized in three equal groups to receive two doses of Avaxim(TM), Epaxal(R), or Havrix(R), 6 to 12 months apart. Seroconversion rates one month after the first dose were 98%, 95%, and 93% for Avaxim(TM), Epaxal(R), and Havrix(R), respectively. Seroconversion rates reached 100% for all vaccine groups one month after the second dose. Anti-HAV geometric mean concentrations (GMCs) were 7,207.7 mIU/mL (95% CI, 6023.1-8684.7), 1,750.5 mIU/mL (95% CI, 1362.9-2248.3), and 1,953.5 mIU/mL (95% CI, 1459.4-2614.7) after two doses of Avaxim(TM), Epaxal(R), and Havrix(R) respectively. Avaxim(TM) was significantly more immunogenic than Epaxal(R) and Havrix(R), whereas there were no significant differences in antibody responses between Epaxal(R) and Havrix(R). Local and systemic solicited adverse events (AEs) were mostly of mild-to-moderate intensity and resolved within 5 days. No serious AEs were reported. In conclusion, all three vaccines are highly immunogenic and well-tolerated in Korean adolescents. (Clinical Trial Registry NCT00483470)

Incidence of hepatitis 'A' infection post vaccination program

The aim of this study is to assess the incidence of Hepatitis 'A' Virus [HAV] infection after the introduction of vaccination program in 2008. Health care settings in Jeddah region, Kingdom of Saudi Arabia. An ecologic record-based study. Data on HAV infections were documented from the health registries of the surveillance unit in Jeddah region. Four hundred sixty-nine HAV infection were documented from 2007 to 2009, the incidence rate revealed a decreasing trend from 4.57 per 100,000 in 2007 to 3.27 per 100,000 in 2009 [p=0.016]. The decreasing trend was demonstrated among Saudis only [p=0.007]. The majority of the cases were in the age groups of 5-14 and 15-44 years. No significant difference could be noticed between males and females. A decreasing trend of HAV infections occurred in Jeddah from 2007 to 2009 among Saudis, which could be partially attributed to the HAV vaccination in 2008. Long-term follow-up is recommended to evaluate the result of vaccination

Evaluation of immunogenicity and tolerability of a live attenuated hepatitis a vaccine in Indian children.

An open non comparative study of a live attenuated H2 strain Hepatitis A vaccine of Chinese origin was carried out in 143 healthy Indian children aged 1 to 12 years (mean age 4.87 2.76 years; 88 boys, 55 girls). At baseline, all were negative for IgG HAV antibodies and had normal hematological and biochemical indices. Two months after a single dose of the vaccine (given subcutaneously), 137 children (i.e. 95.8 %) developed protective antibodies of IgG > 20 mIU / mL. The hematological and biochemical parameters remained within normal limits. There were no adverse events in any except mild fever in one child. In conclusion, live attenuated H2 strain Hepatitis A vaccine in a single dose was found to be immunogenic and safe in Indian children.

Field performance of VAQTA (inactivated, purified hepatitis a vaccine) in Chinese children in Jiangsu.

In Jiangsu, 30% of children between the ages of 5 and 8 years test seropositive for hepatitis A. The safety, tolerability, and immunogenicity of a 2-dose regimen (0, 6 months) of VAQTA (0.5 ml of 25U) administered IM in 50 healthy children aged 5 to 8 years without prior serological screening was evaluated. Blood samples were collected prior to the first dose and after each additional dose of VAQTA to determine the initial anti-HAV serostatus and response rates to the vaccine. Twelve children (24%) were initially seropositive and 38 (76%) were initially seronegative. Four weeks after the primary dose of VAQTA, 34 of the 38 subjects (89.5%, 95% CI 75 to 97) were anti-HAV seropositive. The geometric mean titer was 33.1 mIU/ml (95% CI 22.4 to 49.0). After the booster dose at 6 months, all the subjects were seropositive (37/37), giving a seroconversion of 100% (95% CI: 90, 100). The geometric mean titer was 7585.8 mIU/ml (95% CI: 5623.4 to 10,471.3). Adverse experiences were generally mild and transient. Results of this study are consistent with results from a previous double-blind randomized trial of this vaccine and confirm that VAQTA is highly immunogenic, and generally well-tolerated.

Immunogenicity and safety of an inactivated hepatitis A vaccine in Taiwanese adults and children.

The safety and immunogenicity of an inactivated hepatitis A vaccine (AVAXIM, 160 antigen units) was evaluated in 190 subjects: 50 children aged from 2 to 5 years, 70 children aged from 6 to 17 years and 70 adults aged from 18 to 30 years in a monocentric, open, non-controlled, phase III trial conducted in Taipei, Taiwan from December 1996 to October 1997. The vaccine was administered intramuscularly, with a two-dose schedule 6 months apart. Clinical adverse events were monitored during the seven days following each injection. Hepatitis A virus (HAV) antibody titers were measured by modified radioimmunoassay on the day of inclusion and four weeks after both the first dose and booster injection. Among the 190 subjects who received the first dose, 174 (91.6%) were initially HAV seronegative and 16 (8.4%) were HAV seropositive at inclusion. One hundred and seventy-four subjects (91.6%) received the booster dose and completed the study. One month after the first dose, all the subjects, whatever the age, presented HAV antibody titers over 20 mIU/ml. In children (2 to 17 years), the GMT was 136 mIU/ml at week 4 and 7,906 mIU/ml four weeks after the booster dose. In adults (> or = 18 years), GMT values were 93 mIU/ml at week 4 and 3,655 mIU/ml four weeks after the booster. These results show a strong anamnestic response to the second dose of vaccine and are compatible with long-term antibody persistence in each age group. The vaccine was safe and well tolerated. No vaccine-related serious adverse event occurred. No immediate reaction occurred. The majority of the reactions were reported by adults after the primary injection. Local reactions (pain and redness) were reported by 9.0% and 4.0% of the subjects after the primary and the booster doses, respectively. Systemic reactions (mainly myalgia/arthralgia or asthenia) affected less than 10% of the subjects after the first dose and less than 3% after the booster. Results from this study in a Taiwanese population are consistent with those obtained with the same vaccine in previous European studies in children and adults, and suggest that AVAXIM (160 AU) is suitable for use in all subjects aged over 2 years.