Influenza in the emergency department: 2020 update.

Emergency clinicians must be aware of the current diagnostic and therapeutic recommendations for influenza and the available resources to guide management. This comprehensive review outlines the classification of influenza viruses, influenza pathophysiology, the identification of high-risk patients, and the importance of vaccination, with an update on the 2019-2020 influenza season. Seasonal variations of influenza are discussed, as well as the rationale for limiting testing during periods of high prevalence. Differences between strains of influenza are discussed, as well as the challenges in achieving optimal vaccine effectiveness. Recommendations for use of the currently available oral, intranasal, and intravenous antiviral treatments are provided, as well as utilizing shared decision-making with patients regarding risks and benefits of treatment.