Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Center of Excellence in Clinical Virology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Vaccine. 2020 Nov 10;38(48):7638-7644. doi: 10.1016/j.vaccine.2020.10.002. Epub 2020 Oct 14.
Thailand is one of the countries in the Asia-pacific region that has been most affected by the Enterovirus-A71 (EV-A71) epidemic. An individual who is susceptible to EV-A71 may also be infected asymptomatically, thus, a serological assay is a useful tool to estimate the cumulative incidence of infection in the community and to provide guidance for vaccination scheduling. There have been several candidate EV-A71 vaccines, of which three have been approved and licensed in China. The population target for EV-A71 vaccine is children younger than three years of age. In Thailand, there are limited data available on the seroprevalence of EV-A71 neutralizing (NT) antibodies and the timing of seroconversion in children. This study aims to investigate the seroprevalence and seroconversion rate of EV-A71 NT antibody in a cohort of Thai children. Sera were collected at the King Chulalongkorn Memorial Hospital in Bangkok, Thailand from 100 children between 2015 and 2020. Maternal sera were collected on the day of delivery. Serum samples from children were collected at birth (month 0) and at 2, 7, 18, 24, 36, and 48 months of age to test for EV-A71 NT antibody titers using an enzyme-linked immunosorbent assay (ELISA)-based microneutralization test. The seroprotection rate (NT antibody ≥1:16) in children at months 0, 2, 7, 18, 24, 36, and 48 was 81.0%, 60.0%, 9.0%, 10.0%, 13.0%, 17.0%, and 37.1%, respectively. The seroprotection rate was lowest at month 7 due to waning of the maternal antibody and the immunity of children increased with increasing age. At 48 months of age, less than 40% of children were seroprotected. Children at the age of 6 months should be considered a primary target for vaccination.
泰国是亚太地区受肠病毒 A71（EV-A71）疫情影响最严重的国家之一。易感染 EV-A71 的个体也可能无症状感染，因此血清学检测是估计社区感染累积发生率并为疫苗接种计划提供指导的有用工具。已经有几种候选 EV-A71 疫苗，其中三种在中国获得批准和许可。EV-A71 疫苗的目标人群是三岁以下的儿童。在泰国，关于 EV-A71 中和（NT）抗体的血清流行率和儿童血清阳转时间的数据有限。本研究旨在调查泰国儿童队列中 EV-A71 NT 抗体的血清流行率和血清转化率。在泰国曼谷的朱拉隆功国王纪念医院收集了 2015 年至 2020 年间 100 名儿童的血清。在分娩当天采集了母亲的血清。在出生时（第 0 个月）和 2、7、18、24、36 和 48 个月时采集儿童的血清样本，使用酶联免疫吸附测定（ELISA）-基于微量中和试验检测 EV-A71 NT 抗体滴度。在第 0、2、7、18、24、36 和 48 个月时，儿童的血清保护率（NT 抗体≥1:16）分别为 81.0%、60.0%、9.0%、10.0%、13.0%、17.0%和 37.1%。第 7 个月的血清保护率最低，这是由于母体抗体的衰减和儿童的免疫力随着年龄的增长而增加。在 48 个月时，不到 40%的儿童具有血清保护作用。6 个月大的儿童应被视为疫苗接种的主要目标人群。
