The purpose of this study is to evaluate a) whether the seroconversion rates in children are equivalent after two and/or three partial vaccinations with TICOVAC 0.25 mL and TICOVAC 0.5 mL, and b) whether there is a difference in terms of safety between the two products.

Inclusion Criteria:

• Male and female children aged between 6 and 47 months
• No history of any previous TBE vaccination
• Clinically healthy
• Informed consent provided by the parents

Exclusion Criteria:

• History of allergic reactions, in particular allergic reactions to one of the components of the vaccine
• Suffering from a disease that cannot be effectively treated or stabilised
• Suffering from a disease or undergoing a form of treatment which can be expected to influence immunological functions
• Suffering from a chronic, degenerative and/or inflammatory disease of the central nervous system
• HIV-positivity (no special HIV test required for the purpose of the study)
• Suffering from a febrile disease
• History of vaccination against yellow fever and/or Japanese encephalitis
• Participation in another clinical trial