INTRODUCTION: IXIARO (IC51), a recently approved inactivated Japanese Encephalitis vaccine, is immunogenic and safe in a 0/28 days primary immunization schedule. Neutralizing antibody titers decline with time and booster doses are likely needed to enhance persistence of immunity. OBJECTIVES: To assess the effect of a booster dose on neutralizing JE antibody titers for up to 12 months after boostering. METHODS: In this phase III trial, 198 subjects, who had received primary immunization in a preceding randomized trial, were boosted with IXIARO 15 months after the primary immunization. Neutralizing antibody titers were assessed by plaque-reduction neutralisation test, PRNT. RESULTS: Prior to the booster dose, 69.2% (137/198) of subjects had PRNT50 titers ≥ 1:10. One month after the booster, the rate of subjects with PRNT50 ≥ 1:10 (recognized as a protective titer) was 100%. This rate remained high at 98.5% at 6 and 12 months; GMTs were 22.5 before the booster and 900, 487 and 361 at 1, 6 and 12 months after the booster, respectively. CONCLUSION: A booster dose of IXIARO at 15 months after primary immunization was highly immunogenic with GMTs >5-fold higher than those seen immediately after primary immunization, and remained at high levels for at least 12 months after the booster.
RCT Entities:
INTRODUCTION: IXIARO (IC51), a recently approved inactivated Japanese Encephalitis vaccine, is immunogenic and safe in a 0/28 days primary immunization schedule. Neutralizing antibody titers decline with time and booster doses are likely needed to enhance persistence of immunity. OBJECTIVES: To assess the effect of a booster dose on neutralizing JE antibody titers for up to 12 months after boostering. METHODS: In this phase III trial, 198 subjects, who had received primary immunization in a preceding randomized trial, were boosted with IXIARO 15 months after the primary immunization. Neutralizing antibody titers were assessed by plaque-reduction neutralisation test, PRNT. RESULTS: Prior to the booster dose, 69.2% (137/198) of subjects had PRNT50 titers ≥ 1:10. One month after the booster, the rate of subjects with PRNT50 ≥ 1:10 (recognized as a protective titer) was 100%. This rate remained high at 98.5% at 6 and 12 months; GMTs were 22.5 before the booster and 900, 487 and 361 at 1, 6 and 12 months after the booster, respectively. CONCLUSION: A booster dose of IXIARO at 15 months after primary immunization was highly immunogenic with GMTs >5-fold higher than those seen immediately after primary immunization, and remained at high levels for at least 12 months after the booster.
Authors: Kathryn E Stephenson; Chen Sabrina Tan; Stephen R Walsh; Andrew Hale; Jessica L Ansel; Diane G Kanjilal; Kate Jaegle; Lauren Peter; Erica N Borducchi; Joseph P Nkolola; Tatenda Makoni; Rachel Fogel; Connor Bradshaw; Anna Tyler; Edward Moseley; Abishek Chandrashekar; Katherine E Yanosick; Michael S Seaman; Kenneth H Eckels; Rafael A De La Barrera; Jason Thompson; Peter Dawson; Stephen J Thomas; Nelson L Michael; Kayvon Modjarrad; Dan H Barouch Journal: Lancet Infect Dis Date: 2020-05-06 Impact factor: 25.071
Authors: Elina O Erra; Helena Hervius Askling; Lars Rombo; Jukka Riutta; Sirkka Vene; Sutee Yoksan; Lars Lindquist; Sari H Pakkanen; Eili Huhtamo; Olli Vapalahti; Anu Kantele Journal: Clin Infect Dis Date: 2012-06-13 Impact factor: 9.079
Authors: Elina O Erra; Helena Hervius Askling; Sutee Yoksan; Lars Rombo; Jukka Riutta; Sirkka Vene; Lars Lindquist; Olli Vapalahti; Anu Kantele Journal: Clin Infect Dis Date: 2012-10-16 Impact factor: 9.079