【Cochrane简语概要】预防65岁或以上人群季节性流感及其并发症的疫苗

综述目的 

于2006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老年人（65岁或以上）进行免疫效果的证据。我们使用了随机对照试验中流感疫苗与仿制疫苗或不接种疫苗的对比信息。流感疫苗是通过用能杀死流感病毒（灭活病毒）的化学药品处理流感病毒而制备的，并且通过皮肤注射进行疫苗接种。我们主要关注于疫苗对减少确诊流感，具有头痛，发热，咳嗽和肌肉疼痛（如流感样疾病，influenza-like illness (ILI)）等流感样症状的老年人的数量方面的效果，以及接种疫苗的毒副作用。我们寻找受流感或流感样疾病影响的证据，例如住院，并发症和死亡。仅当有新的试验或疫苗可用时，我们才会在将来更新此综述。

由于历史原因，保留了以前版本研究中67项研究的观察数据，但由于其对综述结论的影响力较小，因此未进行更新。

（图片来源于网络）

本项系统综述研究了哪些内容？ 

导致流感样疾病的病毒超过200种，它们会导致相同的症状（发烧，头痛，酸痛，痛苦，咳嗽和流鼻涕）。如果没有实验室检测，医生将无法区分病毒，因为它们可持续数天，并且很少导致严重疾病。疫苗充其量仅能有效抵抗甲型和乙型流感，它们占所有正在传播的病毒的5％。灭活疫苗是通过用一种“杀死”病毒的特殊化学试剂处理流感病毒而制备的。最终制剂可能包含完整的病毒（全病毒疫苗）或其中的活性部分（分裂或亚单位疫苗）。这些疫苗通常通过皮下注射给药。疫苗中包含的病毒株通常是预期在以下流行季节传播的病毒株（两种A型和一或两种B型株），这是世界卫生组织推荐的（季节性疫苗）。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A型H1N1病毒）。

主要信息 

灭活疫苗可以减少患有流感和流感样疾病老年人的比例。关于死亡的数据很少，我们没有发现因并发症而住院的数据。但是，研究结果的差异意味着我们无法确定这些疫苗在不同季节会产生多大的变化。

主要结果 

我们发现8个随机对照试验（超过5000人），其中4个评价了其危害。这些研究是在1965年至2000年期间在欧洲和美国的社区和住宅护理机构中进行的。

接受流感疫苗的老年人在一个季节内可能会感染较少的流感，从6％降至2.4％，这意味着每30个需要接种灭活流感疫苗的人中，可避免1例流感发生。老年人的流感样疾病可能也更少，从6％降低到3.5％，这意味着需要接种42人才能预防1例流感样疾病。关于肺炎和死亡率的数据资料有限。数据资料不足以确定疫苗对死亡率的影响。一项报告该结果的研究中未发生肺炎病例，也未报告住院数据资料。我们没有足够的数据资料来评价与该人群发烧和恶心有关的危害。

无论研究背景，结局，人群和研究设计如何，流感疫苗对老年人的影响都是中等的。

本系统综述何时进行更新？ 

证据更新到2016年12月31日。

结论: 

与在单一流感季节未接种疫苗的人相比，接受流感疫苗的老年人可能具有较低的流感风险（从6％到2.4％），并且可能具有较低的流感样疾病风险（6 ％至3.5％）。我们不确定这些疫苗在不同季节会产生多大的差异。几乎没有死亡发生，也没有关于住院的数据资料报告。一项报告该结果的研究未发生肺炎病例。我们没有足够的数据资料来评价与该人群发烧和恶心有关的危害。

接种疫苗可降低流感和流感样疾病风险的证据质量受到研究设计或实施偏倚的限制。由于缺乏用于确认流感诊断方法的详细信息，限制了本综述结果的适用性。与并发症相关的现有证据质量差，不充分，且纳入的文献时间久远，并且对于65岁或65岁以上人群的流感疫苗的安全性、效力和效果，未提供明确的公共卫生指导。社会应该投资研究针对老年人的新一代流感疫苗。

译者：梁昌昊；审校：张英英、鲁春丽；编辑排版：张晓雯，北京中医药大学循证医学中心

相关文章链接

【Cochrane Plain Language Summary】Vaccines for preventing seasonal influenza and its complications in people aged 65 or older

Review aim

The aim of this Cochrane Review, first published in 2006, was to summarise research that looks at the effects of immunising the elderly (those aged 65 years or older) with influenza vaccine during influenza seasons. We used information from randomised trials comparing influenza vaccine with dummy vaccine or with nothing. The influenza vaccines were prepared by treating influenza viruses with a chemical that kills the virus (inactivated virus), and the vaccination was given by injection through the skin. We were interested in showing the effects of vaccines on reducing the number of elderly with confirmed influenza, the number who had influenza-like symptoms such as headache, high temperature, cough, and muscle pain (influenza-like illness, of ILI), and harms from vaccination. We looked for evidence of the impact of influenza or ILI such as hospital admission, complications, and death. We will update this review in the future only when new trials or vaccines become available.

Observational data from 67 studies included in previous versions of the review have been retained for historical reasons but have not been updated because of their lack of influence on the review conclusions.

What was studied in this review?

Over 200 viruses cause ILI, producing the same symptoms (fever, headache, aches, pains, cough, and runny nose). Without laboratory tests, doctors cannot distinguish between viruses, as they last for days and rarely lead to serious illness. At best, vaccines are only effective against influenza A and B, which represent about 5% of all circulating viruses. Inactivated vaccine is prepared by treating influenza viruses with a specific chemical agent that 'kills' the virus. Final preparations may contain either the complete viruses (whole-virion vaccine) or the active part of them (split or subunit vaccines). These vaccines are typically administered by injection through the skin. The virus strains contained in the vaccine are usually those that are expected to circulate in the following epidemic seasons (two type A and one or two B strains), which are recommended by the World Health Organization (seasonal vaccine). Pandemic vaccine contains only the virus strain that is responsible for the pandemic (e.g. the type A H1N1 for the 2009 to 2010 pandemic).

Key messages

Inactivated vaccines can reduce the proportion of elderly who have influenza and ILI. Data on deaths were sparse, and we found no data on hospitalisations due to complications. However, variation in the results of studies means we cannot be certain about how big a difference these vaccines will make across different seasons.

Main results

We found eight randomised controlled trials (over 5000 people), of which four assessed harms. The studies were conducted in community and residential care settings in Europe and the USA between 1965 and 2000.

Older adults receiving the influenza vaccine may experience less influenza over a single season, from 6% to 2.4%, meaning that 30 people would need to be vaccinated with inactivated influenza vaccines to avoid one case of influenza. Older adults also probably experience less ILI, from 6% to 3.5%, meaning that 42 people would need to be vaccinated to prevent one case of ILI. The amount of information on pneumonia and mortality was limited. Data were insufficient to be certain about the effect of vaccines on mortality. No cases of pneumonia occurred in one study that reported this outcome, and no data on hospitalisations were reported. We do not have enough information to assess harms relating to fever and nausea in this population.

The impact of influenza vaccines in older people is modest, irrespective of setting, outcome, population, and study design.

How up to date is this review?

The evidence is current to 31 December 2016.

Authors' conclusions: 

Older adults receiving the influenza vaccine may have a lower risk of influenza (from 6% to 2.4%), and probably have a lower risk of ILI compared with those who do not receive a vaccination over the course of a single influenza season (from 6% to 3.5%). We are uncertain how big a difference these vaccines will make across different seasons. Very few deaths occurred, and no data on hospitalisation were reported. No cases of pneumonia occurred in one study that reported this outcome. We do not have enough information to assess harms relating to fever and nausea in this population.

The evidence for a lower risk of influenza and ILI with vaccination is limited by biases in the design or conduct of the studies. Lack of detail regarding the methods used to confirm the diagnosis of influenza limits the applicability of this result. The available evidence relating to complications is of poor quality, insufficient, or old and provides no clear guidance for public health regarding the safety, efficacy, or effectiveness of influenza vaccines for people aged 65 years or older. Society should invest in research on a new generation of influenza vaccines for the elderly.

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