Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA, USA; Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Icddr,b, Dhaka, Bangladesh.
Vaccine. 2017 Dec 15;35(50):6967-6976. doi: 10.1016/j.vaccine.2017.10.074. Epub 2017 Oct 31.
Few trials have evaluated influenza vaccine efficacy (VE) in young children, a group particularly vulnerable to influenza complications. We aimed to estimate VE against influenza in children aged <2 years in Bangladesh; a subtropical setting, where influenza circulation can be irregular.
Children aged 6-23 months were enrolled 1:1 in a parallel, double-blind, randomized controlled trial of trivalent inactivated influenza vaccine (IIV3) versus inactivated polio vaccine (IPV); conducted August 2010-March 2014 in Dhaka, Bangladesh. Children received two pediatric doses of vaccine, one month apart, and were followed for one year for febrile and respiratory illness. Field assistants conducted weekly home-based, active surveillance and ill children were referred to the study clinic for clinical evaluation and nasopharyngeal wash specimen collection. Analysis included all children who received a first vaccine dose and compared yearly incidence of reverse transcription polymerase chain reaction (RT-PCR)-confirmed influenza between trial arms. The VE was estimated as 1-(rate ratio of illness) × 100%, using unadjusted Poisson regression. The trial was registered with ClinicalTrials.gov, number NCT01319955.
Across four vaccination rounds, 4081 children were enrolled and randomized, contributing 2576 child-years of observation to the IIV3 arm and 2593 child-years to the IPV arm. Influenza incidence was 10 episodes/100 child-years in the IIV3 arm and 15 episodes/100 child-years in the IPV arm. Overall, the VE was 31% (95% confidence interval 18, 42%) against any RT-PCR-confirmed influenza. The VE varied by season, but was similar by influenza type/subtype and participant age and sex.
Vaccination of young children with IIV3 provided a significant reduction in laboratory-confirmed influenza; however, exploration of additional influenza vaccine strategies, such as adjuvanted vaccines or standard adult vaccine doses, is warranted to find more effective influenza vaccines for young children in low-income countries.
很少有试验评估流感疫苗在幼儿中的有效性（VE），而幼儿特别容易受到流感并发症的影响。我们旨在评估孟加拉国 2 岁以下儿童中流感疫苗的 VE；这是一个亚热带环境，流感的传播可能不规则。
2010 年 8 月至 2014 年 3 月在孟加拉国达卡，以 1:1 的比例将 6-23 月龄的儿童纳入三价灭活流感疫苗（IIV3）与灭活脊髓灰质炎疫苗（IPV）的平行、双盲、随机对照试验中。儿童接受了两剂儿科疫苗，间隔一个月，并在一年内对发热和呼吸道疾病进行随访。现场助理每周进行家庭主动监测，如果儿童生病，将被转介到研究诊所进行临床评估和采集鼻咽洗液标本。分析包括所有接受第一剂疫苗的儿童，并比较试验组之间每年逆转录聚合酶链反应（RT-PCR）确诊流感的发病率。使用未调整的泊松回归估计 VE，计算公式为 1-(发病率比)×100%。该试验在 ClinicalTrials.gov 注册，编号为 NCT01319955。
在四轮疫苗接种中，共招募了 4081 名儿童并进行了随机分组，为 IIV3 组提供了 2576 个儿童年观察期，为 IPV 组提供了 2593 个儿童年观察期。在 IIV3 组中，流感发病率为每 100 名儿童年 10 例，在 IPV 组中为每 100 名儿童年 15 例。总体而言，任何 RT-PCR 确诊流感的 VE 为 31%（95%置信区间为 18%，42%）。VE 随季节变化而变化，但与流感类型/亚型和参与者年龄及性别无关。
为幼儿接种 IIV3 可显著降低实验室确诊的流感；然而，需要探索其他流感疫苗策略，如佐剂疫苗或标准成人疫苗剂量，以寻找更有效的流感疫苗用于低收入国家的幼儿。
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