Rapid vaccination protocols for commercial vaccines against tick-borne encephalitis.

Although inactivated viral vaccines have been dramatically successful in controlling many of the world's most devastating diseases, they frequently need several injections to ensure high levels of protection, and thus their efficacy is reduced in many situations. We have developed several rapid vaccination protocols for two commercial vaccine preparations against tick-borne encephalitis virus and studied their efficacy in an experimental murine model. Vaccination protocols as brief as two doses given over two days elicit efficient protection against challenge with potentially fatal doses of virus and this protection is afforded as soon as 5 or as long as 100 days after the first vaccination. The very rapid induction of protection and the poor antibody responses observed would suggest that cell-mediated immune responses are the most important mechanisms for the protection elicited by conventional inactivated vaccines against tick-borne encephalitis.