title: Efficacy of virosome hepatitis A vaccine in young children in Nicaragua: randomized placebo-controlled trial.
abstract: Immunization of young children could control hepatitis A virus (HAV) infection, but the efficacy of hepatitis A vaccines in early childhood is unknown. In a randomized, double-blind trial of a single dose of a virosome-formulated, aluminum-free inactivated HAV vaccine in Nicaragua, 274 children (age range, 1.5-6 years) received vaccine or placebo injections; 239 children seronegative for hepatitis A were included in the primary efficacy analysis. HAV infection documented by immunoglobulin M antibodies was the primary end point. Among children seronegative for hepatitis A, infection was diagnosed in 4 children in the vaccine group and 22 children in the placebo group (protective efficacy, 84.6%; 95% confidence interval, 54.7%-96.1%). All infections in children in the vaccine group occurred within 6 weeks. After 6 weeks, protective efficacy was 100% (79.8%-100%). In children in the placebo group, the incidence of HAV infection was 17.6 and that of icteric illness was 1.6 cases/100 person-years. Adverse effects were rare in both children in the vaccine group and children in the placebo group. A single dose of a hepatitis A virosome vaccine is safe and protects young children against HAV infection.
authors.affiliation: Department of Microbiology and Parasitology, Faculty of Medicine, University of León, Nicaragua.
authors.forename: Orlando
authors.initials: O
authors.lastname: Mayorga Pérez
authors.forename: Christian
authors.initials: C
authors.lastname: Herzog
authors.forename: Martina
authors.initials: M
authors.lastname: Zellmeyer
authors.forename: Arnoldo
authors.initials: A
authors.lastname: Loáisiga
authors.forename: Gert
authors.initials: G
authors.lastname: Frösner
authors.forename: Matthias
authors.initials: M
authors.lastname: Egger
mesh_terms: D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006506:Hepatitis A / Q000517:prevention & control*; 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; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D008297:Male; D009527:Nicaragua; D016896:Treatment Outcome; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D022701:Virosomes / Q000008:administration & dosage*
chemical_list: D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D007074:Immunoglobulin G; D015164:Vaccines, Inactivated; D022701:Virosomes