Pakpoom Janewongwirot1, Thanyawee Puthanakit2, Suvaporn Anugulruengkitt3, Watsamon Jantarabenjakul3, Chayapa Phasomsap3, Sompong Chumket3, Sutee Yoksan4, Chitsanu Pancharoen3. 1. Division of Infectious Diseases, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Rama IV Road, Bangkok 10330, Thailand. 2. Division of Infectious Diseases, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Rama IV Road, Bangkok 10330, Thailand; Research Unit in Pediatric Infectious Diseases and Vaccine, Chulalongkorn University, Bangkok, Thailand. Electronic address: thanyawee.p@chula.ac.th. 3. Division of Infectious Diseases, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Rama IV Road, Bangkok 10330, Thailand; Research Unit in Pediatric Infectious Diseases and Vaccine, Chulalongkorn University, Bangkok, Thailand. 4. Center for Vaccine Development, Institute of Molecular Biosciences, Mahidol University, Bangkok, Thailand.
Abstract
BACKGROUND: Japanese Encephalitis chimeric virus vaccine (JE-CV) and SA14-14-2 vaccine are live-attenuated JE vaccines produced from the same virus strain. Data on interchangeability is limited. OBJECTIVES: To evaluate the immunogenicity and safety of JE-CV booster after primary vaccination with SA14-14-2 vaccine. METHODS: This study was an open-label clinical trial in Thai children who had received a primary SA14-14-2 vaccination at 12-24monthsbefore enrollment (ClinicalTrials.gov NCT02602652). JE-CV was administered. A 50% plaque reduction neutralization test (PRNT50) against three virus strains; JE-CV, SA-14-14-2andwild-type JE virus was measured before and 28-days post vaccination. The laboratory was performed at PRNT50 titers ⩾10 (1/dil) were considered seroprotective against JE. Geometric mean titer (GMT) of PRNT50 was calculated. Adverse events were observed for 28days. RESULTS: From March 2014 to June 2015, 50 children (64% male) were enrolled. Mean age and duration after primary vaccination was 26.9 (SD 4.6) and 12.8 (SD 2.7) months, respectively. The proportion of participants who had PRNT50pre and post-booster vaccination were 92% and 96% against JE-CV virus, 56% and 98% against SA-14-14-2 strain and 70% and 98% against wild-type JE virus, respectively. Solicited injection site reactions including erythema, pain and swelling occurred in 18%, 10% and 4% of subjects, respectively. Four children (8%) had fever (⩾37.7Celsius). Eight children (16%) had adverse events, which were not related to the vaccine. CONCLUSIONS: AJE-CV booster dose is highly immunogenic and safe among children who previously received SA14-14-2 vaccine.
BACKGROUND:Japanese Encephalitis chimeric virus vaccine (JE-CV) and SA14-14-2 vaccine are live-attenuated JE vaccines produced from the same virus strain. Data on interchangeability is limited. OBJECTIVES: To evaluate the immunogenicity and safety of JE-CV booster after primary vaccination with SA14-14-2 vaccine. METHODS: This study was an open-label clinical trial in Thai children who had received a primary SA14-14-2 vaccination at 12-24monthsbefore enrollment (ClinicalTrials.gov NCT02602652). JE-CV was administered. A 50% plaque reduction neutralization test (PRNT50) against three virus strains; JE-CV, SA-14-14-2andwild-type JE virus was measured before and 28-days post vaccination. The laboratory was performed at PRNT50 titers ⩾10 (1/dil) were considered seroprotective against JE. Geometric mean titer (GMT) of PRNT50 was calculated. Adverse events were observed for 28days. RESULTS: From March 2014 to June 2015, 50 children (64% male) were enrolled. Mean age and duration after primary vaccination was 26.9 (SD 4.6) and 12.8 (SD 2.7) months, respectively. The proportion of participants who had PRNT50pre and post-booster vaccination were 92% and 96% against JE-CV virus, 56% and 98% against SA-14-14-2 strain and 70% and 98% against wild-type JE virus, respectively. Solicited injection site reactions including erythema, pain and swelling occurred in 18%, 10% and 4% of subjects, respectively. Four children (8%) had fever (⩾37.7Celsius). Eight children (16%) had adverse events, which were not related to the vaccine. CONCLUSIONS: AJE-CV booster dose is highly immunogenic and safe among children who previously received SA14-14-2 vaccine.