Immunogenicity, safety, and interchangeability of two inactivated hepatitis A vaccines in Chilean children.
OBJECTIVE
To compare the immunogenicity, safety, and interchangeability of two pediatric hepatitis A vaccines, Avaxim 80U-Pediatric and Havrix 720, in Chilean children.


METHODS
In this randomized trial, 332 hepatitis A virus (HAV) seronegative children from 1 to 15 years of age received two doses of Avaxim, two doses of Havrix, or Havrix followed by Avaxim, 6 months apart. Anti-HAV antibody titers were measured before and 14 days after the first dose of vaccine, and before and 28 days after the second dose of vaccine. Immediate reactions were monitored; reactogenicity was evaluated from parental reports.


RESULTS
Seroconversion rates after the first vaccination were 99.4% and 100% for Avaxim and Havrix, respectively. Anti-HAV geometric mean concentrations (GMCs) were 138 mIU/ml for Havrix (95% confidence interval (CI): 120; 159) and 311 mIU/ml for Avaxim (95% CI: 274; 353). GMCs increased to 4008 mIU/ml after two doses of Havrix, 8537 mIU/ml following two doses of Avaxim, and 7144 mIU/ml in children who received Havrix with Avaxim as the second dose. Following the first injection, 36% of subjects given Avaxim and 44% given Havrix reported local reactions; 38% of subjects in the Avaxim group and 40% in the Havrix group reported systemic reactions related to vaccination. Solicited reactions were less frequent after the second dose of Avaxim or Havrix, occurring in 27% to 37% of subjects.


CONCLUSIONS
No significant difference in seroconversion rates was seen 14 days after a single dose of vaccine. A two-dose schedule with either vaccine or with Havrix/Avaxim provided a strong booster response. Both vaccines were well tolerated and can be recommended for routine vaccination of Chilean children. Avaxim 80 may be used to complete a vaccine schedule begun with Havrix 720.
Abarca
Katia
K
Centro Médico San Joaquín, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile. katia@med.puc.cl
Ibánez
Isabel
I
Perret
Cecilia
C
Vial
Pablo
P
Zinsou
Jean-Antoine
JA
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002677:Chile; D005260:Female; D006506:Hepatitis A / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D035922:Hepatitis A Antibodies / Q000097:blood*; D022362:Hepatitis A Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D017957:Hepatitis A Virus, Human / Q000276:immunology*; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D008297:Male; D016896:Treatment Outcome; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology
D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D015164:Vaccines, Inactivated