Empirical evidence for the effect of airline travel on inter-regional influenza spread in the United States.
Empirical evidence for the effect of airline travel on inter-regional influenza spread in the United States.
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DOI：
10.1371/journal.pmed.0030401
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发表时间：
2006-09
期刊：
影响因子：
15.8
通讯作者：
Mandl KD
中科院分区：
文献类型：
--
作者：
Brownstein JS;Wolfe CJ;Mandl KD
航空旅行对流感传播的影响一直是使用模拟的许多调查的主题，但很少有经验证据。鉴于流感大流行的威胁日益严重，了解航空旅行在大规模流感传播中的作用尤为重要。最近的几项模拟研究得出的结论是，航空旅行限制可能不会对大流行的进程产生重大影响。在这里，我们评估，与经验数据，航空公司的流量每年在美国的区域间流感传播的作用。我们使用美国疾病控制和预防中心的每周流感和肺炎死亡率，测量了1996年至2005年美国9个流感季节的地区间传播率和流感时间。季节性的特点是带通滤波。我们发现，11月国内航空旅行量（主要围绕感恩节假期）预测流感传播率（r 2 = 0.60; p = 0.014）。我们还发现，国际航空旅行影响流感死亡的时间（r2 = 0.59; p = 0.016）。2001年9月11日恐怖袭击后美国的禁飞令以及随后航空旅行市场的萧条为评估飞行限制提供了一个自然的实验;航空旅行的减少与流感季节的延迟和延长有关。我们提供了第一个经验证据，证明航空旅行在流感的远距离传播中的作用。我们的研究结果表明，国际航空旅行对流感传入时间的重要影响，以及国内航空旅行对美国地区间流感传播速度的影响。大流行防范战略应考虑到航空旅行限制对流感传播的可能好处。从1996年到2005年，流感在美国的时间和传播受到国内和国际航空旅行量的影响。2001年9月11日之后的飞行禁令与流感季节的延迟和延长有关。在北方和南半球，流感流行每年都在冬季“流感季节”发生。尽管这种疾病在大多数年份都表现出非常相似的模式，但人们对地理传播发生的具体机制知之甚少。考虑到1918年、1957年和1969年发生的流感全球流行病（大流行病）以及最近发生的导致高比例受影响人群死亡的禽流感（“禽流感”）局部爆发的可能性，我们需要了解流感是如何传播的，以限制未来大流行病的破坏性影响。从理论上讲，航空旅行可能会在流感的远距离传播中发挥作用。如果是这样，减少或限制航空旅行可能是流感大流行早期阶段适当的公共卫生干预措施。这项研究旨在确定航空旅行对美国流感年度传播的具体影响。研究人员分析了1996年至2005年9个流感季节期间美国9个地区城市流感和肺炎死亡的每周政府记录。他们每年确定疫情在美国蔓延所需的时间以及全国流感死亡高峰的日期。然后，他们利用政府对乘客航空旅行的估计来探索与年度流感流行时间的任何联系。分析发现，流感疫情在美国达到高峰的通常时间约为两周，在九个季节中的五个季节中，全国高峰日期在平均日期2月17日的两天内。一般来说，流感在国内航空旅客人数较少的年份，特别是在11月，传播速度较慢。此外，在国际航空旅客人数较低的年份，特别是在9月，流感季节的高峰期会较晚。这些结果基于肺炎或流感死亡报告，并得到流感病毒监测项目数据的证实，不能用冬季温度的变化或不同年份流行的不同类型流感病毒来解释。值得注意的是，2001年9月11日之后的美国流感季节高峰期推迟了13天，至3月2日，这与恐怖袭击后航空旅行的显著减少相一致，然后在随后的两个流感季节中，随着国际航空旅行恢复到以前的水平，又回到了2月17日。相比之下，调查人员发现，在2001-2002年的法国流感季节，没有航班限制，没有延误。虽然这项研究并没有证明旅行限制会有效地改变流感大流行的进程，但它确实提供了证据，证明航空旅行在美国流感的年度传播中发挥了重要作用。尽管其他因素，与9月11日之后航空旅行的减少有关或无关，可能影响了2001-2002年流感季节的进程，但几年来的一般调查结果表明，航空旅行影响了流感的高峰日期和传播速度。这些发现值得在为下一次流感大流行做准备的过程中加以考虑。请通过http://dx.doi.org/10.1371/journal.pmed.0030401上的本摘要在线版本访问这些网站。世界卫生组织：流感大流行准备页面美国卫生与公众服务部：禽流感和大流行流感信息网站维基百科关于流感大流行的页面（注：维基百科是一个免费的互联网百科全书，任何人都可以编辑）
The influence of air travel on influenza spread has been the subject of numerous investigations using simulation, but very little empirical evidence has been provided. Understanding the role of airline travel in large-scale influenza spread is especially important given the mounting threat of an influenza pandemic. Several recent simulation studies have concluded that air travel restrictions may not have a significant impact on the course of a pandemic. Here, we assess, with empirical data, the role of airline volume on the yearly inter-regional spread of influenza in the United States. We measured rate of inter-regional spread and timing of influenza in the United States for nine seasons, from 1996 to 2005 using weekly influenza and pneumonia mortality from the Centers for Disease Control and Prevention. Seasonality was characterized by band-pass filtering. We found that domestic airline travel volume in November (mostly surrounding the Thanksgiving holiday) predicts the rate of influenza spread (r 2 = 0.60; p = 0.014). We also found that international airline travel influences the timing of influenza mortality (r 2 = 0.59; p = 0.016). The flight ban in the US after the terrorist attack on September 11, 2001, and the subsequent depression of the air travel market, provided a natural experiment for the evaluation of flight restrictions; the decrease in air travel was associated with a delayed and prolonged influenza season. We provide the first empirical evidence for the role of airline travel in long-range dissemination of influenza. Our results suggest an important influence of international air travel on the timing of influenza introduction, as well as an influence of domestic air travel on the rate of inter-regional influenza spread in the US. Pandemic preparedness strategies should account for a possible benefit of airline travel restrictions on influenza spread. Influenza timing and spread in the US from 1996 to 2005 was influenced by the volume of domestic and international air travel. The flight ban after September 11, 2001, was associated with a delayed and prolonged influenza season. In both the northern and southern hemispheres, influenza epidemics occur annually during the winter “flu season.” Although the disease maps out a remarkably similar pattern in most years, little is known about the specific mechanisms by which geographic spread occurs. Given the perennial possibility of influenza global epidemics (pandemics) such as occurred in 1918, 1957, and 1969, as well as the more recent, localized outbreaks of avian influenza (“bird flu”) in which a high proportion of affected people have died, we need to understand how influenza spreads in order to limit the destructive impact of future pandemics. In theory, airline travel might be expected to play a role in the spread of influenza across large distances. If so, reducing or restricting air travel might be an appropriate public health intervention in the early stages of an influenza pandemic. This study was performed to identify specific effects of air travel on the annual spread of influenza in the United States. The researchers analyzed weekly government records on deaths from influenza and pneumonia in cities from nine regions of the US during the nine influenza seasons between 1996 and 2005. For each year, they determined the time it took for the epidemic to spread across the US and the date of the national peak in influenza deaths. They then used government estimates of passenger air travel to explore any connection with the timing of the annual flu epidemics. The analysis found that the usual time for an influenza epidemic to reach peak levels across the US was approximately two weeks, and that the national peak date fell within two days of the average date, February 17, in five of the nine seasons. In general, influenza was found to spread more slowly during years when the number of domestic air travelers, particularly during November, was lower. Also, the peak of the influenza season was found to come later during years when the number of international air travelers, particularly in September, was lower. These results, based on reported deaths from pneumonia or influenza, were corroborated using data from an influenza virus surveillance program, and could not be explained by variations in winter temperatures or by different types of influenza virus circulating in different years. Of note, the peak date of the US influenza season following September 11, 2001, was delayed by 13 days to March 2, consistent with marked reductions in airline travel following the terrorist attack, and then returned to February 17 over the subsequent two influenza seasons as international airline travel returned to its previous levels. In contrast, the investigators found no delay in the 2001–2002 influenza season in France, where flight restrictions were not imposed. While this study does not demonstrate that travel restriction would be effective in altering the course of a flu pandemic, it does provides evidence that air travel plays a significant role in the annual spread of influenza in the United States. Although other factors, related or unrelated to the decrease in air travel after September 11, may have affected the course of the 2001–2002 influenza season, the general findings across several years suggest that air travel affects both the peak date and the rate of spread of influenza. These findings merit consideration in the process of preparing for the next influenza pandemic. Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030401. World Health Organization: influenza pandemic preparedness page US Department of Health and Human Services: avian and pandemic flu information site Wikipedia page on influenza pandemic (note: Wikipedia is a free Internet encyclopedia that anyone can edit)
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影响因子：
120.7
作者：
Barbera, J;Macintyre, A;Layton, M
通讯作者：
Layton, M
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5
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