Surapat AssawawiroonhakarnNopporn ApiwattanakulSamart PakakasamaSuradej HongengUsanarat AnurathapanSutee YoksanChompunuch KlinmalaiPattarana Sae-ChewChonnamet TechasaensiriFaculty of Medicine Ramathibodi Hospital, Mahidol UniversityMahidol University2022-08-042022-08-042021-01-01Pediatric Infectious Disease Journal. (2021), 264-26815320987089136682-s2.0-85102090938https://repository.li.mahidol.ac.th/handle/20.500.14594/78805Background: Children and young adults undergoing hematopoietic stem cell transplantation (HSCT) typically lose their immunity to vaccine-preventable diseases, including Japanese encephalitis (JE). Revaccination against JE in this population has not been well characterized. Methods: This prospective study evaluated the immunogenicity of inactivated Vero cell culture-derived JE vaccine in children and young adults (<25 years of age) who had completed HSCT >1 year prior. Each patient received inactivated Vero cell culture-derived JE vaccine at enrollment and 1 month after enrollment, as well as a booster dose 13 months after enrollment. Serum JE plaque reduction neutralization test and JE-specific T lymphocyte count assay were performed at baseline, 1 month after the second dose, on the day of the booster dose, and 1 month after the booster dose. Results: Thirty-seven patients were enrolled. At baseline, 15 patients (40.5%) had plaque reduction neutralization titer >10, which is considered protective. Among 22 seronegative patients, 15 (68.2%) and 19 (86.4%) exhibited seroconversion after revaccination and booster dose, respectively. Median JE-specific T lymphocyte counts also increased. Twenty of 111 (18.0%) vaccination doses resulted in self-limiting side effects. Conclusions: The inactivated Vero cell culture-derived JE vaccine may be safe and effective for immunization against JE virus in children and young adults who have undergone HSCT.Mahidol UniversityMedicineArticleSCOPUS10.1097/INF.0000000000003007