Immunogenicity of a JE-CV as a Booster Dose After a Primary Vaccination With SA14-14-2 Vaccine
Condition: Japanese Encephalitis
MeSH terms: Encephalitis, Japanese; Encephalitis
Study type: Interventional

Summary: 
      The objective of this study is to measured the Geometric mean titer (GMT) of Japanese
      Encephalitis neutralizing antibody and proportion of seroprotection among the children who
      received a booster dose of JE-CV after the first dose of SA14-14-2 vaccine.
    

Detailed description: 
      Study design: This open label clinical trial in 50 children aged 1-5 years, was conducted at
      King Chulalongkorn Memorial Hospital in Thailand. The protocol was approved by the
      Institutional Review Board of Chulalongkorn University, and the study was performed in
      accordance with Declaration of Helsinki, International Conference on Harmonization Good
      Clinical Practice, the European Directive 2001/20/EC, and written informed consent was
      obtained from parents or a legally acceptable representative before enrolment.

      Vaccines: JE-CV was manufactured by Sanofi Pasteur Biologics Co., USA., and reconstituted
      using 0.4% sodium chloride diluent for injection; each dose 0.5 ml contained 4.0-5.8 log10
      plaque forming units of virus Serology: JE neutralizing antibody levels were assessed using a
      PRNT50 assay. The final end point neutralization titer is the inverse of the highest serial
      dilution of serum that can neutralize ≥ 50% of JE challenge virus. Testing was performed at
      Focus Diagnostics Inc. using JE-CV as a challenge virus.

      Statistical methods: sample size was calculated based on historical data from JE15 study, at
      month 24 after first dose of JE-CV, the GMT of JE neutralizing antibody was 39.4 (95% CI 33.7
      to 46.0) and increase to 2242 (95% CI 1913, 2628) at day 28 post JE-CV booster dose. On the
      assumption that children who received SA14-14-2 vaccine and subsequently get one booster dose
      of JE-CV at 12-24 months later will have GMT of at least 1040, with 80% power and alpha 0.05,
      data at least 43 children need to be collected. When accounted for 15% of children who might
      loss to follow-up or cannot get adequate blood sample, 50 children should be enrolled.

      The per-protocol population will be used for the main immunogenicity analyses. For the main
      parameters, 95% confidence intervals (CIs) of point estimates will be calculated using the
      normal approximation for quantitative data and the exact binomial distribution for
      proportions. The point estimates and their 95% CI of the following will be presented for each
      group of the Geometric Mean (GM) of neutralizing antibody on D0 and D28 and the percentage of
      subjects with neutralizing antibody >=10 at D0 and D28
    

Intervention name(s): a live attenuated chimeric JE vaccine
Intervention type(s): Biological
Intervention description(s): The study included 2 visits (D0 and D28). At the first visit (D0), children were enrolled, collected the blood sample for evaluate the baseline immune status and given a JE-CV as a booster dose. After vaccination, children were observed for 30 minutes to monitor any immediate adverse events. Parents were given a digital thermometer for axillary temperature measurement, a ruler for measuring injection site reactions and a diary card for recording a solicited injection site and systemic reactions.
At the second visit (D28), blood samples were collected for evaluate the immunogenicity.
Other intervention name(s): Japanese Encephalitis Chimeric Virus vaccine
Intervention MeSH terms: Vaccines
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: geometric mean titer; seroprotection; live attenuated chimeric JE vaccine; JE-CV; SA14-14-2 vaccine