Long-term follow-up of Japanese encephalitis chimeric virus vaccine: Immune responses in children

Modeling the long-term persistence of neutralizing antibody in children and toddlers after vaccination with live attenuated Japanese encephalitis chimeric virus vaccine

“…18 In JEC01, all children aged 2-5 years receiving a JE-CV booster dose 1 to 2 years after JE primary vaccination with MBDV were seroprotected 28 days after JE-CV booster vaccination 10 and 97% were seroprotected at 5 years post-booster (sensitivity analysis). 15 No cases of symptomatic JE virus infection were recorded during the 5-year follow-up study 15 ; however, given the endemicity of JE in Thailand, it is possible that the children came into contact with circulating JE virus during this time. It cannot be excluded that natural exposure to JE virus or another flavivirus may have caused a natural booster effect in some of these children, and thus may have impacted the findings from the current modeling exercise.…”

“…Source data (observed individual JE antibody titers) were obtained from a phase 2 randomized controlled immunogenicity study (cross-over design) in Thailand, in which 100 children (2-5 years old) received 1 dose of JE-CV as a booster JE vaccination after primary immunization with the inactivated JE vaccine MBDV and 200 toddlers (12-24 months old) received a single dose of JE-CV as primary immunization. 10,15 All participants received the control hepatitis A vaccine, administered either 28 days before or 28 days after the study vaccine JE-CV in a cross over design; both groups were treated with both products assuming no effect of hepatitis A vaccination on JE vaccination. Antibody titers were measured before JE-CV administration, then on D28, M6, and Y1, 2, 3, 4 and 5 after vaccination.…”

“…14 Single-dose primary immunization of JE-vaccine-naïve toddlers (12-24 months old) elicits a seroprotective response that has been shown to wane to levels of approximately 60% at 5 years after vaccination. 15,16 These findings prompted the recommendation in the product label by the company for use of booster vaccination at 1 to 2 years after the primary dose in children. 17 Indeed, a very strong booster response is observed following a single booster dose in 2-5 year olds primed with JE vaccination, 10,18 with high seroprotection levels persisting for at least 5 years post-booster.…”

“…17 Indeed, a very strong booster response is observed following a single booster dose in 2-5 year olds primed with JE vaccination, 10,18 with high seroprotection levels persisting for at least 5 years post-booster. 15 Information on the longer term duration of seroprotection after single-dose primary and booster JE vaccination in children is needed to provide insight into the potential long-term benefits, and to help make informed decisions about immunization programs. Here, we present the results of statistical modelling to predict long-term antibody responses based on previously published observed antibody titers up to 5 years after vaccination following i) a booster dose of JE-CV in children (2-5 years old) primed with two doses of MBDV and ii) a single-dose primary administration of JE-CV in toddlers (12-24 months old).…”

“…Here, we present the results of statistical modelling to predict long-term antibody responses based on previously published observed antibody titers up to 5 years after vaccination following i) a booster dose of JE-CV in children (2-5 years old) primed with two doses of MBDV and ii) a single-dose primary administration of JE-CV in toddlers (12-24 months old). 10,15 These data are discussed in the context of a comprehensive review of the literature on the long-term persistence of JE neutralizing antibody response following JE-CV vaccination.…”