Seropersistence of tick-borne encephalitis antibodies, safety and booster response to FSME-IMMUN^®0.5 ml in adults aged 18-67 years

Abstract

A clinical study was carried out to evaluate the persistence of tick-borne encephalitis (TBE) antibodies 2 and 3 years after a primary vaccination series (three-dose regimen), and to assess the antibody response to a booster vaccination with FSME-IMMUN. Volunteers (N = 347, 18-67 years) who had received two doses of either FSME-IMMUN or Encepur adults and a third vaccination with FSME-IMMUN were enrolled. Seropositivity rates were assessed by ELISA and neutralization test (NT). After the primary series, seropositivity rates were 99.1% as determined by ELISA and 100% by NT, decreasing to 85% and 96.8% in the first two years and to 88.7% and 95.4% after 3 years. Following booster vaccination, 100% of subjects were seropositive. Age was the only variable with a significant influence on the probability of remaining TBE seropositive 2 or 3 years after the third vaccination. In subjects aged 18-50 years, the pre-booster seropositivity rate was higher (88.7% and 92.3% after 2 and 3 years, respectively) than in those aged 51-67 years (65.5% and 70.9% after 2 and 3 years, respectively). Adverse events after booster vaccination occurred with a low frequency and were predominantly mild. An annual TBE antibody decline rate of 0.58 (based on NT) was estimated to lead to antibody titer decrease from e.g., 260 to 45.6 after 3 years. To conclude, a booster vaccination with FSME-IMMUN, administered 3 years after primary vaccination, is well tolerated and induces a

Antibody persistence after two vaccinations with either FSME-IMMUN® Junior or ENCEPUR® Children followed by third vaccination with FSME-IMMUN® Junior

“…20 ELISA values > 126 VIE U/mL obtained by the Immunozym ® ELISA were considered positive. 21 The Enzygnost ® ELISA categorized results > 10.32 U/mL as positive.…”

Tick-borne encephalitis and golden agers: position paper of the International Scientific Working Group on Tick-borne encephalitis (ISW-TBE)

“…A study on TBE booster vaccination reporting 6-year follow-up data showed that antibody levels were 2 times lower in vaccinees 60 years of age or older, implying some waning of antibodies with increasing age [28]. A study investigating the seropersistence of TBE antibodies in adults aged 18-67 years concluded that the comparatively low seropositivity rates in vaccinees above 50 before their first booster vaccination emphasized the importance of administering the first booster vaccination no later than 3 years after the completion of primary immunization [29].…”

An Inactivated Ross River Virus Vaccine Is Well Tolerated and Immunogenic in an Adult Population in a Randomized Phase 3 Trial

“…More extensive clinical data are available for inactivated, whole-virus vaccines to prevent diseases caused by flaviviruses, which structurally resemble alphaviruses, such as tick-borne encephalitis virus (TBEV), Japanese encephalitis virus, and yellow fever virus (21)(22)(23). The most extensively studied flavivirus vaccine is an alumadjuvanted inactivated whole-virus TBEV vaccine, which has been demonstrated to be safe and immunogenic in a multitude of clinical studies (24)(25)(26)(27)(28)(29)(30) and which has been used in Europe for several decades. In field studies, it has been demonstrated that three immunizations with a 2.4-g dose of the inactivated wholevirus TBEV vaccine provide approximately 99% effectiveness in preventing tick-borne encephalitis (22).…”