Vaccines for preventing tick-borne encephalitis.
Demicheli V., Graves P., Pratt M., Jefferson T.
BACKGROUND: Tick-borne encephalitis is a disease of the central nervous system caused by a virus. Other than the vaccine, there is no treatment for the disease. OBJECTIVES: The objective of this review was to assess the effects of vaccines to prevent tick-borne encephalitis. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group trials register, the Cochrane Vaccine Fields Trials Register, the Cochrane Controlled Trials Register, Medline, Embase and reference lists of articles. We also handsearched the journal Vaccine. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing tick-borne encephalitis vaccines against placebo, control vaccines or comparisons of different doses or schedules of tick-borne encephalitis vaccines. DATA COLLECTION AND ANALYSIS: Two reviewers independently applied inclusion criteria. A panel of six assessors examined trial quality. MAIN RESULTS: Five trials were included. They could not be combined for meta-analysis because of differences in comparisons and outcomes. Four types of tick-borne encephalitis vaccines were used. All the vaccines gave seroconversion rates of over 87%. There were frequent reports of systemic and local adverse effects. REVIEWER'S CONCLUSIONS: Tick-borne encephalitis vaccines appear to be highly immunogenic, but the relationship between seroconversion and clinical protection has not been established. Although adverse effects were commonly reported, none were severe or life threatening.