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

Abstract

Tick-borne encephalitis (TBE) virus, which is usually divided into European, Far Eastern and Siberian subtypes, is a serious public health problem in several European and Asian countries. Vaccination is the most effective measure to prevent TBE; cross-subtype protection elicited by the TBE vaccines is biologically plausible since all TBE virus subtypes are closely related. This manuscript systematically explores available data on the cross-subtype immunogenicity elicited by the currently available Western vaccines based on the European subtype. Completed immunization course of 3 doses of both Western vaccines determined very high seroconversion/seropositivity rates against both Far Eastern and Siberian subtypes among previously flavivirus-naïve subjects. All but one study found no statistically significant difference in titers of neutralizing antibodies against strains belonging to homologous and heterologous subtypes. 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 (risk ratio = 0.98, p = 0.83) or enzyme-linked immunosorbent (risk ratio = 0.95, p = 0.44) assays after 2 vaccine doses. This suggests that, in regions where a heterogeneous TBE virus population circulates, vaccines based on the European subtype may be used alongside vaccines based on the Far Eastern subtype. Studies on the field effectiveness of TBE vaccines and investigation of vaccination failures, especially in countries where different subtypes co-circulate, will further elucidate TBE vaccination-induced cross-subtype protection.

EAN consensus review on prevention, diagnosis and management of tick‐borne encephalitis

“…An animal study in Far Eastern Russia detecting the antibodies to the Far Eastern subtype of TBE after vaccination with two European and two Russian vaccines demonstrated a high seroconversion rate and high and stable antibody levels [107]. A meta-analysis of 14 studies demonstrated high seroconversion rates against Far Eastern and Siberian subtypes of TBE after immunization with both European vaccines [108].…”

Comparison of the Immunogenicity and Safety of Two Pediatric TBE Vaccines Based on the Far Eastern and European Virus Subtypes

“…Evaluations of the reactogenicity and immunogenicity of whole virion, inactivated, and concentrated vaccines against TBE have been conducted repeatedly; however, the majority of these studies analyzed collected immunization data corresponding to the conventional vaccination schedule [12][13][14] or the rapid schedule [15][16][17]. Data from comparative studies of reactogenicity and immunogenicity of different TBE vaccines using different immunization schedules in a single experiment were rather limited [18].…”

Analysis of Efficacy and Safety of Tick-Borne Encephalitis Vaccines

“…Данные систематического обзора и мета-анализа много-численных клинических исследований [23] свидетельствуют о том, что все современные зарегистрированные вакцины про-тив КЭ обеспечивают высокий профиль безопасности и имму-нологическую эффективность.…”