International Journal of Medical Microbiology 296 (2006) S1, 202–207 MINI-REVIEW Persistence of antibodies after vaccination against tick-borne encephalitis Pamela Rendi-Wagner a , Olaf Zent b,Ã , Wolfgang Jilg c , Annelie Plentz c , Jiri Beran d , Herwig Kollaritsch a a Department of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Austria b Chiron Vaccines, Emil-von-Behring-Str. 76, D-35041 Marburg, Germany c University of Regensburg, Germany d Department of Infectious Diseases, University Hospital, Hradec Kralove, Czech Republic Abstract Active vaccination against the tick-borne encephalitis (TBE) virus has successfully been implemented in endemic countries for many years. However, little was known about persistency of antibodies after completion of the primary vaccination and/or TBE booster immunization. Five recently performed serological follow-up studies in adults have now revealed that the persistence of protective immunity following at least one booster immunization was longer than expected. Notably, studies which analyzed different age groups indicate differences between younger adults aged 18–49 years and older adults aged X50 years with respect to TBE antibody persistence and the immune response following a subsequent booster dose. To summarize, the serological studies included in this analysis generally support a reconsideration of current TBE booster recommendations and a prolongation of booster intervals at least in younger adults. r 2006 Elsevier GmbH. All rights reserved. Keywords: Tick-borne encephalitis; Vaccine; Booster immunization; Immunity Introduction Active vaccination appears to be the most effective means of prevention of tick-borne encephalitis (Barret et al., 2004). Thus, TBE vaccination strategies have successfully been implemented in many European countries, where TBE is endemic. The development and recent licensure of improved TBE vaccine formula- tions has rendered it necessary to re-evaluate recom- mendations for booster intervals, which have been unchanged for many years. Noticeably, little is known about persistence of antibodies after primary vaccina- tion and/or TBE booster immunizations: Only a few serological studies have been published during the last years; and these shall be reviewed in this article. In this context, the persistence of TBE antibodies when using different immunization schedules for primary TBE immunization is of particular interest. TBE immunization schedules for primary immunization There are two different immunization schedules registered for primary immunization against TBE for the widely used European TBE vaccines (i.e. licensed versions of Encepur s , Chiron Behring GmbH & Co KG, Germany, and FSME-IMMUN s , Baxter AG, Austria) (Table 1). The conventional immunization schedule consists of three immunizations (Table 2), which for licensed ARTICLE IN PRESS www.elsevier.de/ijmm 1438-4221/$ - see front matter r 2006 Elsevier GmbH. All rights reserved. doi:10.1016/j.ijmm.2006.01.030 Ã Corresponding author. Tel.: +49 6421 39 4759; fax: +49 6421 39 4667. E-mail address: olaf_zent@chiron.com (O. Zent).