Journal Article

Tick-borne encephalitis (TBE) vaccine failures

Gredmark-Russ, Sara, Rosdahl, Anja, Hansson, Karin, Insulander, Mona, Lindquist, Lars, Askling, Helena H., Vene, Sirkka

2020

Overview

BACKGROUND: Southern Sweden is endemic for tick borne encephalitis (TBE), with Stockholm County as one of the high-risk areas. The aim of this study was to describe cases of vaccine failures, and to optimize future vaccination recommendations. METHODS: Patients with TBE were identified in the notification database at the Department of Communicable Disease Control and Prevention in the county of Stockholm during 2006-2015. Vaccine failure was defined as TBE despite adherence to the recommended vaccination schedule with at least two doses. Clinical data were extracted from medical records. RESULTS: A total of 1004 TBE cases were identified, 53 (5%) were defined as vaccine failures. In this latter group the median age was 62 years (6-83). Forty-three (81%) patients were over 50 years of age and two were children. Approximately half of the patients had comorbidities with diseases affecting the immune system accounting for 26% of all cases.Vaccine failures following the third or fourth vaccine dose accounted for 36 (68%) of the patients. Severe and moderate TBE disease affected 81% of the cases. CONCLUSION: To our knowledge, this is the largest documented cohort of TBE-vaccine failures. Vaccine failure after five TBE-vaccine doses is rare. Our data provides rationale for adding an extra priming dose to the age group 50 years and older.

• Subject: TBE / TBEV / vaccination / vaccine failure