Absolute humidity and the seasonal onset of influenza in the continental United States.

TitleAbsolute humidity and the seasonal onset of influenza in the continental United States.
Publication TypeJournal Article
Year of Publication2010
AuthorsShaman, J, Pitzer, VE, Viboud, C, Grenfell, BT, Lipsitch, M
JournalPLoS biology
Volume8
Issue2
Paginatione1000316
Date Published2010 Feb
ISSN1545-7885
KeywordsHumans, Humidity, Influenza, Human, Models, Statistical, Seasons, United States
Abstract

Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent reanalysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here, we extend these findings to the human population level, showing that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions.

Alternate JournalPLoS Biol.