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Evidence summaries

Vaccines for Preventing Tick-Borne Encephalitis

Tick-borne encephalitis vaccines appear to be highly immunogenic. However, the relationship between seroconversion and clinical protection is less clear. Level of evidence: "B"

A Cochrane review [Abstract] 1 included 11 trials with a total of 8 184 participants (6 586 adults and 1 598 children). Different versions of three types of TBE vaccines were tested (IPVE, FSME-IMMUN, and Encepur). No trials reported on cases of clinical TBE, but all reported on antibody titre (seroconversion). All the vaccines gave seroconversion rates of over 87%. There were frequent reports of systemic and local adverse effects, none of which were severe.

A meta-analysis 2 assessed the cross-subtype immunogenicity elicited by the currently available Western vaccines based on the European subtype. 14 RCTs were included into the qualitative and 4 into the quantitative analysis. Completed immunization course of 3 doses of both Western vaccines (FSME-IMMUN and Encepur) determined very high seroconversion/seropositivity rates against both Far Eastern and Siberian subtypes among previously flavivirus-naive subjects. Pooled analysis of randomized controlled trials on head-to-head comparison of immunogenicity of Western and Russian TBE vaccines did not reveal differences in seroconversion rates against Far Eastern isolates in either hemagglutination inhibition (RR 0.98, p=0.83) or enzyme-linked immunosorbent (RR 0.95, p=0.44) assays after 2 vaccine doses.

A commercially funded study 3 evaluated TBE antibody persistence after 3-5 years in children (aged 5-15 years): 2 groups previously primed with 3 doses of Encepur Children; and 2 groups previously primed with 2 doses of FSME-IMMUN followed by a third dose of Encepur. In the Encepur groups (full series), protective neutralization titers of HASH(0x2f82cc8)10 were detected in 98-100% of children up to 5 years after their last primary vaccination. In contrast, only 65-70% subjects in the FSME-IMMUN groups (mixed series) displayed titers HASH(0x2f82cc8)10 after 3 years.

Comment: The quality of evidence is downgraded by limitations in study quality (inadequate or unclear allocation concealment).

References

  • Demicheli V, Debalini MG, Rivetti A. Vaccines for preventing tick-borne encephalitis. Cochrane Database Syst Rev. 2009;(1):CD000977. [PubMed]
  • .Domnich A, Panatto D, Arbuzova EK et al. Immunogenicity against Far Eastern and Siberian subtypes of tick-borne encephalitis (TBE) virus elicited by the currently available vaccines based on the European subtype: systematic review and meta-analysis. Hum Vaccin Immunother 2014;10(10):2819-33. [PubMed]
  • Wittermann C, Izu A, Petri E et al. Five year follow-up after primary vaccination against tick-borne encephalitis in children. Vaccine 2015;33(15):1824-9.[PubMed]

Primary/Secondary Keywords