【Cochrane简语概要】用以在健康成年人中预防流感的疫苗

综述目的 

于1999年首次发表的此次Cochrane综述的目的是：总结在流感季节使用流感疫苗对健康成年人进行免疫的效果。我们从比较疫苗同假疫苗或不使用疫苗的随机试验中获取相关数据。我们尤其注意使用基于灭活流感病毒疫苗的研究，这种疫苗通过化学药物杀死流感病毒并将其通过皮肤注射。我们评估了疫苗对减少确诊为流感的成年人和流感样症状比如头痛、发烧、咳嗽和肌肉酸痛的成年人数量。我们也评估了住院情况和疫苗引起的伤害。由于历史原因保留了以前版本研究报告的数据，但因对综述结论缺乏影响而未予更新。

该综述研究了什么？ 

超过200种病毒会导致流感样疾病，并产生与流感相同的症状（发烧、头痛、疼痛、咳嗽和流鼻涕）。如果没有实验室检测，医生无法区分它们，因为它们都持续数天，且很少导致严重疾病或死亡。根据世界卫生组织（季节性疫苗）的建议，疫苗中所含的病毒的种类通常是那些预计在接下来的流感季节中会流行的病毒。大流行性流感疫苗只含有导致大流行流感的病毒株（例如2009年至2010年大流行的甲型H1N1病毒）。

主要结果 

我们找到了52项临床试验，包含超过8万名成人。由于报告的细节不足，我们无法确定70%的研究的偏倚影响。大约15%的研究设计和执行合理。我们尤其关注使用灭活疫苗的25项研究报告的结果。注射流感疫苗可能有较小的对流感和流感样症状的保护作用（证据可靠性一般），每71名成年人接种疫苗能预防一例流感，每29名接种则可预防一例流感样疾病。接种疫苗可能对住院有很小甚至没有影响（低可靠性证据）或工作日缺勤天数。

我们不确定灭活流感疫苗对孕妇预防流感和流感样疾病的保护作用，或者说至少是作用有限。

在孕期接种积极性疫苗没有表明对流产或胎儿死亡有显著性影响，不过证据集仅限于观察性研究。

关键信息 

灭活疫苗可降低健康成年人（包括孕妇）患流感或流感样疾病的比例，不过作用很有限。我们不确定灭活疫苗对流感季节中工作日旷工天数或严重流感并发症的影响。

综述如何保持最新？ 

证据更新到2016年12月31日。

结论: 

与未接种疫苗的人相比，接种疫苗的健康成年人患流感的风险可能有所降低，从超过2%降到不到1%（证据可靠性中等）。接种疫苗可能也减少了流感样疾病的可能，不过用绝对数字衡量的话，有效程度随设定的不同而变化。预防流感样疾病的保护效果变化可能部分由于症状的分类不一致。接种疫苗使得住院情况和旷工天数略减的证据可靠性较低。本综述中，在妈妈和新生儿中疫苗对流感和流感样疾病的保护作用看起来比其他群体要小。

疫苗增加了副作用的风险，包括发烧有较小的增长，恶心和呕吐的比率不明。疫苗对孕妇和新生儿的保护作用也不大。本次综述中，我们没有在比较性研究里发现流感疫苗和严重副作用相关的任何证据。15项（29%）随机对照试验有医药界赞助。

【Cochrane Plain Language Summary】Vaccines to prevent influenza in healthy adults

Review aim

The aim of this Cochrane Review, first published in 1999, was to summarise research that looks at the effects of immunising healthy adults with influenza vaccines during influenza seasons. We used information from randomised trials comparing vaccines with dummy vaccines or nothing. We focused on the results of studies looking at vaccines based on inactivated influenza viruses, which are developed by killing the influenza virus with a chemical and are given by injection through the skin. We evaluated the effects of vaccines on reducing the number of adults with confirmed influenza and the number of adults who had influenza-like symptoms such as headache, high temperature, cough, and muscle pain (influenza-like illness, or ILI). We also evaluated hospital admission and harms arising from the vaccines. Observational data included in previous versions of the review have been retained for historical reasons but have not been updated due to their lack of influence on the review conclusions.

What was studied in this review?

Over 200 viruses cause ILI, which produces the same symptoms (fever, headache, aches, pains, cough, and runny nose) as influenza. Without laboratory tests, doctors cannot distinguish between ILI and influenza because both last for days and rarely cause serious illness or death. The types of virus contained in influenza vaccines are usually those that are expected to circulate in the following influenza seasons, according to recommendations of the World Health Organization (seasonal vaccine). Pandemic vaccine contains only the virus strain that is responsible of the pandemic (i.e. the type A H1N1 for the 2009 to 2010 pandemic).

Main results

We found 52 clinical trials of over 80,000 adults. We were unable to determine the impact of bias on about 70% of the included studies due to insufficient reporting of details. Around 15% of the included studies were well designed and conducted. We focused on reporting of results from 25 studies that looked at inactivated vaccines. Injected influenza vaccines probably have a small protective effect against influenza and ILI (moderate-certainty evidence), as 71 people would need to be vaccinated to avoid one influenza case, and 29 would need to be vaccinated to avoid one case of ILI. Vaccination may have little or no appreciable effect on hospitalisations (low-certainty evidence) or number of working days lost.

We were uncertain of the protection provided to pregnant women against ILI and influenza by the inactivated influenza vaccine, or this was at least very limited.

The administration of seasonal vaccines during pregnancy showed no significant effect on abortion or neonatal death, but the evidence set was observational.

Key messages

Inactivated vaccines can reduce the proportion of healthy adults (including pregnant women) who have influenza and ILI, but their impact is modest. We are uncertain about the effects of inactivated vaccines on working days lost or serious complications of influenza during influenza season.

How up to date is this review?

The evidence is current to 31 December 2016.

Authors' conclusions: 

Healthy adults who receive inactivated parenteral influenza vaccine rather than no vaccine probably experience less influenza, from just over 2% to just under 1% (moderate-certainty evidence). They also probably experience less ILI following vaccination, but the degree of benefit when expressed in absolute terms varied across different settings. Variation in protection against ILI may be due in part to inconsistent symptom classification. Certainty of evidence for the small reductions in hospitalisations and time off work is low. Protection against influenza and ILI in mothers and newborns was smaller than the effects seen in other populations considered in this review.

Vaccines increase the risk of a number of adverse events, including a small increase in fever, but rates of nausea and vomiting are uncertain. The protective effect of vaccination in pregnant women and newborns is also very modest. We did not find any evidence of an association between influenza vaccination and serious adverse events in the comparative studies considered in this review. Fifteen included RCTs were industry funded (29%).

译者：逄誉；审校：李迅；编辑排版：张晓雯，北京中医药大学循证医学中心

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