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NIH Study Sheds Light on Role of Climate in Flu Transmission
Two types of environmental conditions — cold/dry and humid/rainy — are associated with seasonal influenza epidemics, according to an epidemiological study led by researchers at the National Institutes of Health (NIH). The study, published in PLoS Pathogens, presents a simple climate-based model that maps influenza activity globally and accounts for the diverse range of seasonal patterns observed across temperate, subtropical, and tropical regions.
The findings could be used to improve existing current influenza transmission models, and could help target surveillance efforts and optimize the timing of seasonal vaccine delivery, according to lead researcher Cecile Viboud, PhD.
After assessing the role of local climatic variables on virus seasonality in a global sample of study sites, the researchers found that temperature and specific humidity were the best individual predictors of the months of maximum influenza activity, known as influenza peaks. The team discovered that, in temperate regions, influenza was more common 1 month after periods of minimum specific humidity. These periods happened to coincide with months of lowest temperature.
Although the study offers researchers a new tool in the global effort to track the spread of influenza, climate is only one of several potential drivers of influenza seasonality, the researchers say. Further work should focus, for example, on examining the role of population travel and other factors in influenza transmission.
The authors conclude that a better understanding of the environmental, demographic, and social drivers of the seasonality of infectious disease is crucial for optimizing interventions.
Source: NIH; March 8, 2013.