Antibody response following administration of two paediatric tick-borne encephalitis vaccines using two different vaccination schedules

Two paediatric tick-borne encephalitis vaccines, Encepur® Children and FSME-IMMUN® Junior, are used widely in Europe. This study compared the immunogenicity and safety of both vaccines, administered using the conventional (Days 0, 28, and 300) or accelerated (Days 0, 14, and 300) schedule and evaluated whether a third dose of Encepur® Children can complete a primary vaccination course initiated with FSME-IMMUN® Junior. A total of 334 children 1 to <11 years of age were enrolled in this Phase IV randomized, controlled, single-blind, multi-centre trial. All subjects, irrespective of study arm, received Encepur® Children as the third dose on Day 300. The percentage of subjects with antibody titres ≥10, as determined by neutralization test (NT), was assessed and local and systemic reactions were monitored and solicited. Within both the conventional and accelerated schedules, the proportion of subjects achieving an NT ≥ 10 was higher in the group that received Encepur® Children, compared with the group that received FSME-IMMUN® Junior, at Days 42 and 300 (conventional schedule Day 300, P < 0.001 Encepur® Children versus FSME-IMMUN® Junior; accelerated schedule Days 42 and 300, P < 0.001 Encepur® Children versus FSME-IMMUN® Junior). The third dose of Encepur® Children led to a substantial increase in the proportion of subjects in the FSME-IMMUN® Junior groups achieving NT ≥ 10. Overall, >95% of all children achieved NT ≥ 10, on completion of the primary vaccination course. Encepur® Children provides an immune response, measured by neutralizing TBE antibodies, that is superior to FSME-IMMUN® Junior and can successfully be used to complete a primary vaccination course initiated with FSME-IMMUN® Junior. Both vaccines were well tolerated, with comparable safety profiles; no vaccine-related serious adverse events were reported.