Safety and immunogenicity of an inactivated Vero cell_derived Japanese encephalitis vaccine (IXIARO®, JESPECT®) in a pediatric population in JE non-endemic countries: An uncontrolled, open-label phase 3 study

Abstract

Background: Young travelers to South-East Asia may be at risk for Japanese encephalitis (JE).

Methods: IXIARO^® (0.25 ml or 0.5 ml, depending on age) were administrated to 100 travelers aged ≥ 2 months to < 18 years. Solicited AEs were collected for 7 days after each injection, unsolicited adverse events (AEs) for a total of 7 months. JE neutralizing antibodies were assessed in 64 subjects.

Results: The most common solicited local AEs were redness (3/12 subjects), induration and tenderness (both 1/12) with 0.25 ml IXIARO^®, and tenderness (44/88) and pain (22/88) with 0.5 ml IXIARO^®. Common solicited systemic AEs were diarrhea (2/12) and loss of appetite (1/12) with 0.25 ml IXIARO^® and muscle pain (27/88) and excessive fatigue (10/88) with 0.5 ml IXIARO^®. In total, up to day 56, AEs were reported by 10/12 (83.3%) of subjects who received the 0.25 ml dose and 67/88 (76.1%) of those vaccinated with the 0.5 ml dose. All subjects (62/62; 100%) developed protective levels of JE neutralizing antibodies by Day 56 and 31/34 (91.2%) retained protective titers at Month 7.

Conclusions: IXIARO^® was generally well tolerated in children, with an overall AE profile similar to adults. IXIARO^® was highly immunogenic in both dose groups.

Keywords: Children; IXIARO; Immunogenicity; Japanese encephalitis vaccine; Safety.