A comparison of the immunogenicity and safety between a new pediatric Tick-E-Vac vaccine based on the tick-borne encephalitis virus (TBEV) strain Sofjin and FSME-IMMUN Junior vaccine was performed in the Sverdlovsk region. The vaccine strains differ from strains of the Siberian subtype of TBEV that dominates in the region.

The goal of a study published in Advances in Virology was to compare the immunogenicity and safety of new pediatric Tick-E-Vac vaccines – based on the TBEV strain Sofjin and FSME-IMMUN Junior vaccine.

The present study was performed on 163 children aged 1-15 years, who received one of the vaccines according to either a conventional or rapid vaccination schedule. Immunogenicity was assessed based on the seroprotection rates and titers of virus-neutralizing antibodies.

The results showed no significant differences in either the immunogenicity or reactogenicity of the pediatric vaccines based on strains of the Far Eastern or European subtypes of TBEV. In addition, there was acceptable reactogenicity and high immunogenicity of the pediatric form of Tick-E-Vac and FSME-IMMUN Junior. Under conventional and rapid vaccination schedules, in the thirty days after the second injection, seroprotection rates were 100% for Tick-E-Vac and greater than 95% for FSME-IMMUN Junior. However, 14 days after the second injection, seroprotection rates were significantly lower – ranging from 50-63%, regardless of the vaccine used. The observed adverse reactions were mild-to-moderate for both vaccines under both schedules, with total adverse event rates of less than 25%. Furthermore, reactogenicity was not associated with the gender or age of the recipients. On the other hand, 14 days after the second vaccine injection according to the rapid schedule, a statistically significant difference in TBEV-neutralizing antibodies (nAbs) titers was identified between groups of children with and without reported reactions. Any differences in the reactogenicity or immunogenicity of the studied vaccines—based on strains of FE or Eur TBEV subtypes—have not been demonstrated in children living in the region in which strains of the Sib subtype of TBEV are dominating.

Source: Advances in Virology. 2019 Dec 24;2019:5323428. doi: 10.1155/2019/5323428.