Oregon State University, Corvallis, 97331, USA.
Am J Epidemiol. 2011 Jan 15;173(2):127-35. doi: 10.1093/aje/kwq347. Epub 2010 Nov 16.
Experimental and epidemiologic evidence indicates that variations of absolute humidity account for the onset and seasonal cycle of epidemic influenza in temperate regions. A role for absolute humidity in the transmission of pandemic influenza, such as 2009 A/H1N1, has yet to be demonstrated and, indeed, outbreaks of pandemic influenza during more humid spring, summer, and autumn months might appear to constitute evidence against an effect of humidity. However, here the authors show that variations of the basic and effective reproductive numbers for influenza, caused by seasonal changes in absolute humidity, are consistent with the general timing of pandemic influenza outbreaks observed for 2009 A/H1N1 in temperate regions, as well as wintertime transmission of epidemic influenza. Indeed, absolute humidity conditions correctly identify the region of the United States vulnerable to a third, wintertime wave of pandemic influenza. These findings suggest that the timing of pandemic influenza outbreaks is controlled by a combination of absolute humidity conditions, levels of susceptibility, and changes in population-mixing and contact rates.
实验和流行病学证据表明，绝对湿度的变化是导致温带地区流感爆发和季节性循环的原因。绝对湿度在大流行性流感（如 2009 年 A/H1N1 流感）传播中的作用尚未得到证实，而且在春季、夏季和秋季湿度较高的情况下爆发大流行性流感，似乎构成了对湿度影响的反证。然而，在这里，作者表明，由于绝对湿度的季节性变化，流感的基本和有效繁殖数的变化与在温带地区观察到的 2009 年 A/H1N1 流感大流行以及冬季流行流感的大流行时间一致。事实上，绝对湿度条件正确地确定了美国易受第三次冬季大流行性流感影响的地区。这些发现表明，大流行性流感爆发的时间是由绝对湿度条件、易感性水平以及人群混合和接触率的变化共同控制的。
