Smith S, Demicheli V, Di Pietrantonj C, Harnden A R, Jefferson T, Matheson N J, Rivetti A
Oxford University, Institute of Health Sciences, Old Road Headington, Oxford, UK, OX3 7LF.
Cochrane Database Syst Rev. 2006 Jan 25(1):CD004879. doi: 10.1002/14651858.CD004879.pub2.
In children and adults the consequences of influenza are mainly absences from school and work, however the risk of complications is greatest in children and people over 65 years old.
To appraise all comparative studies evaluating the effects of influenza vaccines in healthy children; assess vaccine efficacy (prevention of confirmed influenza) and effectiveness (prevention of influenza-like illness) and document adverse events associated with receiving influenza vaccines.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2005); OLD MEDLINE (1966 to 1969); MEDLINE (1969 to December 2004); EMBASE (1974 to December 2004); Biological Abstracts (1969 to December 2004); and Science Citation Index (1974 to December 2004). We wrote to vaccine manufacturers and a number of corresponding authors of studies in the review.
Any randomised controlled trials (RCTs), cohort and case-control studies of any influenza vaccine in healthy children under 16 years old.
Two authors independently assessed trial quality and extracted data.
Fifty-one studies involving 263,987 children were included. Seventeen papers were translated from Russian. Fourteen RCTs and 11 cohort studies were included in the analysis of vaccine efficacy and effectiveness. From RCTs, live vaccines showed an efficacy of 79% (95% confidence interval (CI) 48% to 92%) and an effectiveness of 33% (95% CI 28% to 38%) in children older than two years compared with placebo or no intervention. Inactivated vaccines had a lower efficacy of 59% (95% CI 41% to 71%) than live vaccines but similar effectiveness: 36% (95% CI 24% to 46%). In children under two, the efficacy of inactivated vaccine was similar to placebo. Thirty-four reports containing safety outcomes were included, 22 including live vaccines, 8 inactivated vaccines and 4 both types. The most commonly presented short-term outcomes were temperature and local reactions. The variability in design of studies and presentation of data was such that meta-analysis of safety outcome data was not feasible.
AUTHORS' CONCLUSIONS: Influenza vaccines are efficacious in children older than two years but little evidence is available for children under two. There was a marked difference between vaccine efficacy and effectiveness. That no safety comparisons could be carried out emphasizes the need for standardisation of methods and presentation of vaccine safety data in future studies. It was surprising to find only one study of inactivated vaccine in children under two years, given recent recommendations to vaccinate healthy children from six months old in the USA and Canada. If immunisation in children is to be recommended as public-health policy, large-scale studies assessing important outcomes and directly comparing vaccine types are urgently required.
在儿童和成人中，流感的后果主要是缺课和旷工，然而，儿童和65岁以上人群发生并发症的风险最高。
评估所有评价流感疫苗对健康儿童影响的比较研究；评估疫苗效力（预防确诊流感）和效果（预防流感样疾病），并记录接种流感疫苗相关的不良事件。
我们检索了Cochrane对照试验中心注册库（CENTRAL）（2005年第1期Cochrane图书馆）；旧版医学索引（1966年至1969年）；医学索引（1969年至2004年12月）；EMBASE（1974年至2004年12月）；生物学文摘（1969年至2004年12月）；以及科学引文索引（1974年至2004年12月）。我们写信给疫苗生产商以及本综述中多项研究的若干通讯作者。
任何针对16岁以下健康儿童接种任何流感疫苗的随机对照试验（RCT）、队列研究和病例对照研究。
两位作者独立评估试验质量并提取数据。
纳入了51项涉及263,987名儿童的研究。17篇论文由俄语翻译而来。疫苗效力和效果分析纳入了14项RCT和11项队列研究。在RCT中，与安慰剂或无干预措施相比，对于两岁以上儿童，减毒活疫苗显示效力为79%（95%置信区间（CI）48%至92%），效果为33%（95%CI 28%至38%）。灭活疫苗的效力（59%，95%CI 41%至71%）低于减毒活疫苗，但效果相似：36%（95%CI 24%至46%）。对于两岁以下儿童，灭活疫苗的效力与安慰剂相似。纳入了34篇包含安全性结果的报告，其中22篇涉及减毒活疫苗，8篇涉及灭活疫苗，4篇涉及两种疫苗。最常出现的短期结果是体温和局部反应。研究设计和数据呈现的差异使得对安全性结果数据进行荟萃分析不可行。
流感疫苗对两岁以上儿童有效，但两岁以下儿童的相关证据很少。疫苗效力和效果之间存在显著差异。无法进行安全性比较突出表明未来研究需要对疫苗安全性数据的方法和呈现进行标准化。鉴于美国和加拿大最近建议对六个月以上的健康儿童进行疫苗接种，令人惊讶的是仅发现一项针对两岁以下儿童的灭活疫苗研究。如果要将儿童免疫接种作为公共卫生政策推荐，迫切需要开展大规模研究来评估重要结果并直接比较疫苗类型。
