Leung Ting F, Chan Renee W Y, Kwok Angela, Ho Wendy C S, Tao Mars K P, Hon Kam L, Cheng Frankie W T, Li Albert M, Chan Paul K S
Department of Paediatrics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong.
Department of Microbiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong.
Influenza Other Respir Viruses. 2017 Jul;11(4):319-327. doi: 10.1111/irv.12455. Epub 2017 May 25.
Influenza imposes substantial healthcare burden in children, which can be prevented by vaccination. Influenza vaccination coverage varies widely among childhood populations worldwide, which has significant impact on herd immunity and usefulness of influenza vaccine. However, there are limited real-life data on influenza vaccine effectiveness (VE) in children.
This prospective study aimed to investigate clinical spectrum of childhood influenza and VE in preventing influenza in Hong Kong children.
A total of 623 children were recruited from 15 kindergartens and primary schools. Parents completed a questionnaire on subjects' health and influenza vaccination history. Flocked nasopharyngeal swabs (FNPSs) were collected in biweekly school visits during 2014-2015 influenza seasons. Influenza A and B viruses were detected and typed by molecular assays.
A total of 2633 FNPS samples were collected, with two or more samples being obtained from 607 (97.4%) of subjects. Thirty-six (11.2%) subjects had influenza A or B in 2014, whereas all 19 (6.3%) subjects identified in 2015 had influenza A. Ninety-nine subjects reported influenza-like illness (ILI), and nine illness visits were arranged. Influenza vaccination was protective against ILI but not mild laboratory-confirmed influenza by surveillance. Moderate overall influenza VE of 42%-52% was observed for ILI, and subgroup analyses showed much higher VE for both ILI (70.9% vs 34.6%) and mild laboratory-confirmed influenza (44.0% vs -6.2%) in school-age children than preschoolers who were vaccinated within 12 months.
Mild laboratory-confirmed influenza infection is common in children during influenza seasons. Influenza vaccination is effective against ILI but not mild infection identified by surveillance.
流感给儿童带来了沉重的医疗负担，而接种疫苗可预防流感。全球儿童群体中流感疫苗接种率差异很大，这对群体免疫和流感疫苗的效用有重大影响。然而，关于儿童流感疫苗效力（VE）的实际数据有限。
这项前瞻性研究旨在调查香港儿童流感的临床谱以及预防流感的疫苗效力。
从15所幼儿园和小学招募了623名儿童。家长完成了一份关于受试者健康状况和流感疫苗接种史的问卷。在2014 - 2015年流感季节期间，每两周进行一次学校访视时收集植绒鼻咽拭子（FNPS）。通过分子检测法检测并分型甲型和乙型流感病毒。
共收集了2633份FNPS样本，607名（97.4%）受试者提供了两份或更多样本。2014年有36名（11.2%）受试者感染甲型或乙型流感，而2015年确定的19名（6.3%）受试者均感染甲型流感。99名受试者报告了流感样疾病（ILI），并安排了9次就诊。通过监测发现，流感疫苗可预防ILI，但对轻度实验室确诊流感无效。观察到ILI的总体流感疫苗效力为42% - 52%，亚组分析显示，在12个月内接种疫苗的学龄儿童中，ILI（70.9%对34.6%）和轻度实验室确诊流感（44.0%对 - 6.2%）的疫苗效力均远高于学龄前儿童。
轻度实验室确诊的流感感染在流感季节的儿童中很常见。流感疫苗对ILI有效，但对监测发现的轻度感染无效。
