Long-term Serologic Follow-up of Children Vaccinated with a Pediatric Formulation of Virosomal Hepatitis A Vaccine Administered With Routine Childhood Vaccines at 12-15 Months of Age.
The aim of this open-label, active-controlled, parallel group, phase 2 follow-up study was to assess the long-term immunogenicity of Epaxal Junior, the pediatric dose of an aluminum-free virosomal inactivated hepatitis A virus (HAV) vaccine, in children receiving routine childhood vaccines (RCV).



Healthy children (12-15 months old, ≥8 kg weight) were randomized (1:1:1) to group A: Epaxal Junior + RCV (day 1); group B: Epaxal Junior (day 1) + RCV (day 29) and group C: Havrix 720 + RCV (day 1). All 3 groups received 2 doses of HAV vaccines 6 months apart. Children who completed the primary study were followed up from 18 months to 7.5 years post booster.



Of 291/327 randomized children who had completed the primary study, 157 were followed for the 7.5-year analysis (group A: 50; group B: 54; and group C: 53). Of these, 152 children had protective levels of anti-HAV antibodies [≥10 mIU/mL; 98% (group A); 96.3% (group B); 96.2% (group C)]. Anti-HAV geometric mean concentrations were similar in groups A and B at all the time points (1.5-, 2.5-, 3.5-, 5.25- and 7.5-year time point) but slightly lower in group C. Predictions of the median duration of persistence of seroprotective antibody levels, using the linear mixed model were similar in all groups: (group A: 19.1 years, group B: 18.7 years, group C: 17.3 years).



Immunization with Epaxal Junior administered with RCVs at 12 months elicited protective response beyond 7.5 years in almost all children. Assessing the kinetic of anti-HAV antibody titers decline over time, the moment to reach antibody concentrations below the accepted protective level may occur earlier than previously estimated.
From the *Soroka University Medical Center, Beer-Sheva, Israel; †Schneider Children's Medical Center, Petach Tikva and Sackler Faculty of Medicine, Tel Aviv, Israel; ‡Janssen Research & Development, LLC, Raritan, New Jersey; and §Janssen Vaccines AG, Berne, Switzerland.
Ron
R
Dagan
Shai
S
Ashkenazi
Gilat
G
Livni
Oscar
O
Go
Partha
P
Bagchi
Michal
M
Sarnecki
D005260:Female; D005500:Follow-Up Studies; D006506:Hepatitis A / Q000276:immunology / Q000517:prevention & control; D035922:Hepatitis A Antibodies / Q000097:blood; D022362:Hepatitis A Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood* / Q000276:immunology; D017957:Hepatitis A Virus, Human / Q000276:immunology; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007223:Infant; D008297:Male; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000276:immunology; D022721:Vaccines, Virosome / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000276:immunology
D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D015164:Vaccines, Inactivated; D022721:Vaccines, Virosome; C530970:epaxal berna