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

Area of Science:

• Vaccinology
• Hepatology
• Immunology

Background:

• Development of novel inactivated hepatitis A vaccines is ongoing.
• Evaluation of vaccine safety, reactogenicity, and immunogenicity is crucial.
• Monitoring antibody kinetics post-vaccination provides insight into immune response.

Purpose of the Study:

• To assess the safety, reactogenicity, and immunogenicity of a single-dose inactivated hepatitis A vaccine (1440 EI.U.).
• To monitor the kinetics of anti-hepatitis A virus (antiHAV) antibodies for one year post-vaccination.
• To evaluate the efficacy of a booster dose at 12 months.

Main Methods:

• An open clinical trial involving 194 healthy adult healthcare volunteers.
• Administration of a single intramuscular dose of hepatitis A vaccine at month 0 and a booster at month 12.
• Serologic follow-up of antiHAV antibodies and liver enzymes at specified intervals, with monthly sampling for a subgroup.

Main Results:

• The single-dose vaccine was well-tolerated with high seroconversion rates (80% at 2 weeks, 99% at 1 month).
• High persistence of antiHAV antibodies (94%) was observed one year after the single dose.
• A booster dose at 12 months resulted in 100% seroconversion and a significant increase in geometric mean titer (GMT).

Conclusions:

• The inactivated hepatitis A vaccine is safe and highly immunogenic, inducing rapid antibody production.
• The vaccine demonstrates sustained protective antibody levels for one year, supporting a 12-month booster schedule.
• This vaccination schedule is practical for travel and occupational health, potentially improving compliance.