Related Experiment Videos
Protection against hepatitis A by an inactivated vaccine
B L Innis1, R Snitbhan, P Kunasol
1Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
Insights
This study shows that an inactivated hepatitis A vaccine is safe and effective. Two doses provide at least one year of protection against hepatitis A virus infection in children.
Area of Science:
- Virology
- Immunology
- Vaccinology
Background:
- Hepatitis A virus (HAV) infection poses a significant public health risk, particularly in endemic areas.
- Effective vaccination strategies are crucial for controlling HAV transmission.
Purpose of the Study:
- To assess the safety and efficacy of a novel inactivated hepatitis A vaccine.
- To determine the duration of protection conferred by the vaccine.
Main Methods:
- A double-blind, randomized, community-based controlled trial involving over 40,000 children aged 1-16 years in Thailand.
- Participants received either the inactivated hepatitis A vaccine or a control hepatitis B vaccine, with a crossover design implemented after 18 months.
- Surveillance for hepatitis A cases was conducted by monitoring school absences and laboratory confirmation.
Main Results:
- The inactivated hepatitis A vaccine demonstrated an excellent safety profile, with no serious adverse reactions observed.
- Antibody levels against HAV reached protective thresholds (≥20 mIU/mL) in 94% of recipients after two doses and 99% after a booster.
- Vaccine efficacy was high: 94% after two doses and 95% cumulatively, with only a few breakthrough infections noted, primarily in the control group.
Conclusions:
- The inactivated hepatitis A vaccine is safe for use in children.
- Two doses of the vaccine provide robust protection against hepatitis A for at least one year, with sustained high antibody levels after a booster dose.
Objective:
To evaluate the safety and efficacy of a new inactivated hepatitis A vaccine.
Design:
Double-blind randomized controlled trial stratified by community.
Setting:
Community-based in Thailand.
Study Participants:
A total of 40,119 children, aged 1 to 16 years, attending 148 primary schools: 38,157 (95%) entered surveillance a mean of 138 days after receiving vaccine dose 1; 33,586 (84%) completed the controlled trial of 532 days; and 31,075 (81%) received crossover vaccine and remained under surveillance until day 844.
Intervention:
Participants received hepatitis A vaccine or control hepatitis B vaccine starting January 7, 1991 (doses in months 0, 1, and 12), and crossed over to the alternate vaccine 18 months later.
Main Outcome Measure:
Cases of hepatitis A (symptoms, alanine aminotransferase levels of 45 U/L or higher, and IgM to hepatitis A virus) were identified by evaluating school absences of 2 or more days.
Results:
There were no serious adverse reactions despite administration of more than 109,000 doses of hepatitis A vaccine. Among initially seronegative recipients of two doses of hepatitis A vaccine, the proportion with 20 mIU/mL or more of antibody to hepatitis A virus before and 5 months after a 1-year booster was 94% and 99%, respectively. Of 6976 episodes of illness during the controlled trial, there were 40 cases of hepatitis A; 38 were in the control group. Of the 40 cases, six, all in controls, occurred after the 1-year booster dose. Following two doses of hepatitis A vaccine (days 138 through 386), protective efficacy was 94% (95% confidence interval, 79% to 99%); cumulative efficacy including the postbooster period (days 138 to 532) was 95% (95% confidence interval, 82% to 99%). The two hepatitis A vaccine recipients who had symptomatic infections (257 and 267 days after dose 1) appeared to have been partially protected since their illnesses were brief and associated with only slight increases in alanine aminotransferase.
Conclusions:
Inactivated hepatitis A vaccine is safe; when administered in two doses, it protects against hepatitis A for at least 1 year.