Jefferson T, Smith S, Demicheli V, Harnden A, Rivetti A, Di Pietrantonj C
Cochrane Vaccines Field, ASL 20, 15100 Alessandria, Italy.
Lancet. 2005;365(9461):773-80. doi: 10.1016/S0140-6736(05)17984-7.
We aimed to assess evidence of efficacy and effectiveness of live attenuated and inactivated influenza vaccines in children up to 16 years of age.
We searched the Cochrane Library, MEDLINE, EMBASE Biological Abstracts, and Science Citation Index to June, 2004, in any language, and contacted vaccine manufacturers and authors of relevant studies to identify additional data. We included randomised, cohort, and case-control studies comparing efficacy of vaccines against influenza (reduction in laboratory-confirmed cases), effectiveness of vaccines against influenza-like illness (reduction in symptomatic cases), or both, with placebo or no intervention. We analysed the following outcomes: influenza, influenza-like illness, admissions, school absences, complications, and secondary transmission.
We included 14 randomised controlled trials, eight cohort studies, one case-control study, and one randomised controlled trial of intraepidemic use of the vaccines. Live attenuated influenza vaccines had 79% efficacy and 38% effectiveness in children older than 2 years compared with placebo or no immunisation. Inactivated vaccines had lower efficacy (65%) than live attenuated vaccines, and in children aged 2 years or younger they had similar effects to placebo. Effectiveness of inactivated vaccines was about 28% in children older than 2 years. Vaccines were effective in reducing long school absences (relative risk 0.14 [95% CI 0.07-0.27]). Studies assessing the effects of vaccines against secondary cases, lower-respiratory tract disease, acute otitis media, and hospital stay suggested no difference with placebo or standard care, but lacked statistical power.
Influenza vaccines (especially two-dose live attenuated vaccines) are efficacious in children older than 2 years. Efficacy and effectiveness of the vaccines differed strikingly. Only two small studies assessed the effects of influenza vaccines on hospital admissions and no studies assessed reductions in mortality, serious complications, and community transmission of influenza. If influenza immunisation in children is to be recommended as public-health policy, large-scale studies assessing such important outcomes and undertaking direct comparisons of vaccines are urgently needed.
我们旨在评估减毒活流感疫苗和灭活流感疫苗在16岁及以下儿童中的有效性和效果证据。
我们检索了截至2004年6月的Cochrane图书馆、MEDLINE、EMBASE生物学文摘和科学引文索引，不限语言，并联系了疫苗生产商和相关研究的作者以获取更多数据。我们纳入了随机对照试验、队列研究和病例对照研究，这些研究比较了疫苗预防流感的有效性（实验室确诊病例的减少）、疫苗预防流感样疾病的效果（有症状病例的减少）或两者，与安慰剂或无干预措施进行比较。我们分析了以下结果：流感、流感样疾病、住院、缺课、并发症和二次传播。
我们纳入了14项随机对照试验、8项队列研究、1项病例对照研究以及1项疫苗流行期间使用的随机对照试验。与安慰剂或未免疫相比，减毒活流感疫苗在2岁以上儿童中的有效性为79%，效果为38%。灭活疫苗的有效性（65%）低于减毒活疫苗，在2岁及以下儿童中，其效果与安慰剂相似。灭活疫苗在2岁以上儿童中的效果约为28%。疫苗在减少长期缺课方面有效（相对危险度0.14 [95%可信区间0.07 - 0.27]）。评估疫苗对二代病例、下呼吸道疾病、急性中耳炎和住院影响的研究表明，与安慰剂或标准治疗相比无差异，但缺乏统计学效力。
流感疫苗（尤其是两剂次减毒活疫苗）在2岁以上儿童中有效。疫苗的有效性和效果存在显著差异。仅有两项小型研究评估了流感疫苗对住院的影响，且没有研究评估流感疫苗对死亡率、严重并发症和社区传播的降低作用。如果将儿童流感免疫作为公共卫生政策推荐，迫切需要进行大规模研究来评估这些重要结果并对疫苗进行直接比较。
