title: Immunogenicity of live attenuated Japanese encephalitis SA 14-14-2 vaccine among Sri Lankan children with previous receipt of inactivated JE vaccine.
abstract: The performance of live attenuated Japanese Encephalitis SA 14-14-2 vaccine (CD-JEV) among children previously given inactivated mouse brain-derived JE vaccine (IMBV) is unknown. We evaluated the safety and immunogenicity of CD-JEV administered to 2- and 5-year-old children in Sri Lanka.
  
  
  
  In this open-label, single arm trial in the Colombo District of Sri Lanka, generally healthy children 2 and 5years of age who had previously received two and three doses of IMBV, respectively, were administered one dose of CD-JEV subcutaneously. Participants were monitored for adverse events for one year post-vaccination. Serum neutralizing antibody responses were evaluated pre and 28 and 365days post-vaccination using JE plaque reduction neutralization test and characterized as the proportion of participants seroconverting. Seroconversion was defined as either reaching a titer considered seroprotective (⩾1:10) among participants with a baseline titer <1:10 or achieving at least a 4-fold rise in titer among participants with a baseline titer ⩾1:10.
  
  
  
  Of 305 children given CD-JEV, 294 were included in the primary analysis of immunogenicity. Prior to vaccination, 144/147 (98.0%) 2-year-olds and 146/147 (99.3%) 5-year-olds had seroprotective levels. 28days post-vaccination, 79/147 [53.7% (95% CI, 45.3-62.0)] 2-year olds and of 60/147 [40.8% (95% CI, 32.8-49.2)] 5-year olds achieved seroconversion. Among 2-year-olds, geometric mean titers (GMTs) rose from 697 to 3175 28days post-vaccination. Among 5-year-olds, GMTs rose from 926 to 2776. Most adverse reactions were mild, and no serious adverse events were related to study vaccination.
  
  
  
  Administration of CD-JEV to these children with pre-existing neutralizing JE antibody titers was safe and resulted in substantial boosting of antibody levels. These results may inform other countries in Asia considering switching from IMBV to now WHO-prequalified CD-JEV vaccine to combat this disease of public health importance.
authors: Epidemiological Unit, Ministry of Healthcare and Nutrition, Colombo, Sri Lanka.
authors: Pushpa Ranjan
authors: PR
authors: Wijesinghe
authors: Epidemiological Unit, Ministry of Healthcare and Nutrition, Colombo, Sri Lanka.
authors: M R Nihal
authors: MRN
authors: Abeysinghe
authors: Mahidol University, Bangkok, Thailand.
authors: Sutee
authors: S
authors: Yoksan
authors: Chengdu Institute of Biological Products, Chengdu, China.
authors: Yafu
authors: Y
authors: Yao
authors: Chengdu Institute of Biological Products, Chengdu, China.
authors: Benli
authors: B
authors: Zhou
authors: Chengdu Institute of Biological Products, Chengdu, China.
authors: Lei
authors: L
authors: Zhang
authors: PATH, Seattle, WA, USA.
authors: Jessica A
authors: JA
authors: Fleming
authors: PATH, Seattle, WA, USA.
authors: Anthony A
authors: AA
authors: Marfin
authors: PATH, Seattle, WA, USA. Electronic address: cvictor@path.org.
authors: John C
authors: JC
authors: Victor
mesh_terms: D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D002675:Child, Preschool; D004664:Encephalitis Virus, Japanese / Q000276:immunology*; D004672:Encephalitis, Japanese / Q000453:epidemiology / Q000517:prevention & control; D005260:Female; D006801:Humans; D007117:Immunization, Secondary; D000071497:Immunogenicity, Vaccine; D022321:Japanese Encephalitis Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D008297:Male; D013188:Sri Lanka / Q000453:epidemiology; D065566:Subcutaneous Absorption; D014611:Vaccination; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D022321:Japanese Encephalitis Vaccines; D014613:Vaccines, Attenuated; D015164:Vaccines, Inactivated
keywords: Clinical trial; Humoral immune response; Japanese encephalitis vaccines; Safety; Secondary immune response