Japanese Encephalitis Vaccine (Inactivated, Adsorbed) [IXIARO®]

Abstract

▴ The Japanese encephalitis vaccine IC-51 (IXIARO®) is an inactivated virus (strain SA₁₄-14-2) that is manufactured in cultured Vero cells and is currently being developed for preventive vaccination against the Japanese encephalitis virus. ▴ Administration of IXIARO® as a two-dose treatment in healthy adults provided high levels of seroprotection against Japanese encephalitis virus. Immune responses at 56 days post-vaccination, including seroconversion rates and geometric mean titres, were noninferior to those seen with a currently available licensed vaccine. Seroprotection was achieved 1 week after second vaccination. ▴ Long-term seroprotection was also observed with the vaccine, with seroconversion rates and geometric mean titres maintained at both 6 and 12 months post-vaccination. ▴ Coadministration with a hepatitis A vaccine had no effect on the immunogenicity of IXIARO®. Additionally, the vaccine immunogenicity was not compromised in subjects with pre-existing vaccine-induced antibodies for tick-borne encephalitis, a related flavivirus. ▴ Vaccine immunogenicity was also observed in paediatric volunteers, with seroconversion rates not significantly different to an active comparator at 56 days post-vaccination. ▴ The safety and tolerability profile of IXIARO® was generally similar to that of placebo with respect to systemic adverse events, and was associated with a numerically lower frequency of local injection site adverse events than the active comparator vaccine.