Related Experiment Videos
Immunization of seronegative infants with hepatitis A vaccine (HAVRIX; SKB): a comparative study of two dosing
C L Troisi1, F B Hollinger, D S Krause
1Division of Molecular Virology, Baylor College of Medicine, Houston, TX, USA. ctroisi@utsph.sph.uth.tmc.edu
Insights
This study shows an inactivated Hepatitis A virus (HAV) vaccine is safe and effective in infants. High seroconversion rates indicate its potential inclusion in infant immunization schedules.
Area of Science:
- Virology
- Immunology
- Pediatrics
Background:
- Hepatitis A virus (HAV) infection poses a public health risk, particularly for infants and young children.
- Current HAV vaccines are not widely studied or licensed for children under two years old.
Purpose of the Study:
- To assess the immunogenicity and safety of an inactivated HAV vaccine in seronegative infants.
- To compare two different infant immunization schedules for HAV vaccine.
Main Methods:
- Fifty-three healthy infants received an inactivated HAV vaccine at different ages (2, 4, 6 months or 2, 4, 15 months).
- Antibody concentrations were measured using radioimmunoassay, compared against a WHO reference standard.
- Infants were monitored for local and systemic reactions.
Main Results:
- No serious adverse reactions were reported in any infants.
- Seroconversion rates reached 100% in Group 1 and 93% in Group 2, three months post-third dose.
- Geometric mean anti-HAV concentrations were comparable between groups at various time points.
Conclusions:
- The inactivated HAV vaccine is highly immunogenic and well-tolerated in seronegative infants.
- The vaccine's efficacy supports its potential integration into routine infant immunization programs.
- Maternal antibodies may transiently affect vaccine response in some infants.
Abstract:
Hepatitis A virus (HAV) infection is of public health significance among infants and diapered children. Although two licensed HAV vaccines are available, they have not been assessed widely in children under the age of 2 years and are not currently licensed for this age group. The purpose of this study was to evaluate the immunogenicity and reactogenicity of HAV vaccine in seronegative infants. Fifty-three healthy infants were immunized with 360 ELISA Units (EL.U.) of an inactivated HAV vaccine at 2, 4, and 6 (Group 1) or 2, 4, and 15 months of age (Group 2). These injections were not received on the same day that participants received their routine childhood immunizations. HAV serum antibodies were detected using a modified radioimmunoassay procedure and concentrations were calculated using a World Health Organization serum anti-HAV reference standard. No serious-systemic or local reactions were noted among the immunized infants. Three months following the third immunization, seroconversion rates were 100% and 93% in groups 1 and 2, respectively. No significant differences were observed in the geometric mean anti-HAV concentrations between the two groups at comparable time points, i.e. 2 months after the second dose, 3 months after the third dose, and 19 months after the first dose. Three infants, not included in the data presented above, had preexisting maternal antibodies; one never responded to the vaccine and the other two did not respond until maternal antibody levels had become reduced. The results indicate that the inactivated HAV vaccine is highly immunogenic in seronegative infants and could be included in the routine harmonized infant immunization schedule.