title: Irregular tick-borne encephalitis vaccination schedules: the effect of a single catch-up vaccination with FSME-IMMUN. A prospective non-interventional study.
abstract: BACKGROUND
  Intervals longer than recommended are frequently encountered between doses of tick borne encephalitis virus (TBE) vaccines in both residents of and travelers to endemic regions. In clinical practice the management of individuals with lapsed TBE vaccination schedules varies widely and has in common that the underlying immunological evidence is scarce.
  The aim of this study was to generate data reliable enough to derive practical recommendations on how to continue vaccination with FSME-IMMUN in subjects with an irregular TBE vaccination history. Antibody response to a single catch-up dose of FSME-IMMUN was assessed in 1115 adults (age ≥16 years) and 125 children (age 6-15 years) with irregular TBE vaccination histories.
  
  
  RESULTS
  Subjects of all age groups developed a substantial increase in geometric mean antibody concentration after a single catch-up TBE vaccination which was consistently lower in subjects with only one previous TBE vaccination compared to subjects with two or more vaccinations. Overall, >94% of young adults and children, and >93% of elderly subjects with an irregular TBE vaccination history achieved antibody levels ≥25U/ml irrespective of the number of previous TBE vaccinations.
  
  
  CONCLUSIONS
  We conclude that TBE vaccination of subjects with irregular vaccination histories should be continued as if the previous vaccinations had been administered in a regular manner, with the stage of the vaccination schedule being determined by the number of previous vaccinations. Although lapsed vaccination schedules may leave subjects temporarily with inadequate protection against TBE infection, adequate protection can quickly be re-established in >93% of the subjects by a single catch-up dose of FSME-IMMUN, irrespective of age, number of previous vaccinations, and time interval since the last vaccination.
authors.affiliation: Medical Affairs, Baxter Deutschland GmbH, Im Breitspiel 13, 69126 Heidelberg, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Schosser
authors.affiliation: Medical Affairs Group DACH, Baxter Deutschland GmbH, Edisonstrasse 4, 85716 Unterschleißheim, Germany. Electronic address: anja_reichert@baxter.com.
authors.forename: Anja
authors.initials: A
authors.lastname: Reichert
authors.affiliation: Institute of Medical Informatics, Biometry, and Epidemiology, Faculty of Medicine, University of Munich, Marchioninistrasse 15, 81377 München, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Mansmann
authors.affiliation: Global R&D, Baxter Bioscience, IZD Tower, Wagramer Strasse 17-19, 1220 Wien, Austria.
authors.forename: Bernd
authors.initials: B
authors.lastname: Unger
authors.affiliation: Division of Paediatric Infectious Diseases and Vaccinology, University Children's Hospital, Spitalstrasse 33, 4031 Basel, Switzerland.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Heininger
authors.affiliation: Neurological Clinic, Klinikum Pforzheim GmbH, Kanzlerstrasse 2-6, 75175 Pforzheim, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kaiser
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D004675:Encephalitis, Tick-Borne / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014765:Viral Vaccines / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D014765:Viral Vaccines
keywords: Delayed TBE vaccination; Irregular scheme; Reestablish protection