Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Feb 14;227(4):512-521.
doi: 10.1093/infdis/jiac075.

Tick-Borne Encephalitis in Vaccinated Patients: A Retrospective Case-Control Study and Analysis of Vaccination Field Effectiveness in Austria From 2000 to 2018

Isabel Santonja  1 , Karin Stiasny  1 , Astrid Essl  2 , Franz X Heinz  1 , Michael Kundi  3 , Heidemarie Holzmann  1
Affiliations

Tick-Borne Encephalitis in Vaccinated Patients: A Retrospective Case-Control Study and Analysis of Vaccination Field Effectiveness in Austria From 2000 to 2018

Isabel Santonja et al. J Infect Dis. .

Abstract

Background: There are discrepant observations on the severity of tick-borne encephalitis (TBE) in vaccinated persons. We, therefore, analyzed the occurrence of severe and mild disease in hospitalized vaccinated and nonvaccinated patients with TBE and determined the field effectiveness (FE) of vaccination against these forms of disease.

Methods: The study covered all patients hospitalized with TBE in Austria from 2000 to 2018. Clinical diagnoses in vaccinated and age- and sex-matched nonvaccinated patients were compared in a nested case-control study. FE was calculated based on vaccination coverage and incidences in the nonvaccinated and vaccinated population.

Results: Of 1545 patients hospitalized with TBE, 206 were vaccinated. In those, a higher proportion of severe TBE was observed, especially in children. FE was high in all age groups and against all forms of disease. The higher proportion of severe TBE can be explained by a lower FE against severe than against mild disease, a difference especially pronounced in children (FE, 82.7% for severe vs 94.7% for mild disease).

Conclusions: The FE of TBE vaccination is excellent. The observed higher proportion of severe disease in vaccinated persons with TBE does not reflect a higher risk associated with vaccination but is rather due to a somewhat lower FE against severe TBE. Because this effect was more pronounced in children, we recommend adapting the immunization schedule.

Keywords: course of disease; tick-borne encephalitis; tick-borne encephalitis vaccination; vaccination failures; vaccine field effectiveness.

PubMed Disclaimer

Conflict of interest statement

Potential conflicts of interest. The project was supported by Pfizer as an IIR project (grant WI235042; with H. H. and M. K. as principal investigators and I. S. involved in the project); and by the Center for Virology, Medical University of Vienna. The Center for Virology received an IIR grant from Pfizer (grant WI239484; “Epidemiological changes of TBE in Austria,” with K. S. as principal investigator). All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Publication types

LinkOut - more resources