- October 2, 2014
Influenza viruses are responsible for acute respiratory illnesses during winter seasons in temperate climates. Epidemic influenza occurs due to small changes in surface glycoproteins, a process known as antigenic drift. Large changes in those proteins, known as antigenic shift, are responsible for larger pandemic influenza outbreaks. Seasonal influenza is expected annually, but the threat of pandemic influenza due to a large change in seasonal strains or introduction of a novel strain requires infection prevention and control programs to have surveillance, interventions, and emergency preparedness plans in place. Influenza can cause a spectrum of disease in humans, ranging from a self-limited respiratory infection to a more fulminant illness. The very young and very old are more susceptible to severe disease, as are individuals with certain underlying medical conditions. Several antiviral drugs are available for treatment of influenza, but vaccination and respiratory etiquette are the primary control strategies. Each year, vaccines are modified to reflect the strains most likely to be circulating.