Seasonal patterns in flu transmission have observational validity in temperate climates. However, there is no consensus mechanism explaining the increased incidence of flu during the winter. The physiologic effects of cold weather and dry air on the upper respiratory system may contribute to immune dysfunction and increased susceptibly to flu-causing pathogens. Low temperature limits the absolute humidity of air. Persistent exposure to dry air leads to airway desiccation and failure of the mucociliary system. The resultant physiologic and histopathologic changes that occur in the airway increase susceptibility to flu-causing pathogens. Laryngoscope, 130:309-313, 2020.
Keywords: Flu; absolute humidity; mucociliary dysfunction; relative humidity; vapor pressure.
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