Influenza viruses cause an acute respiratory illness, which is experienced annually by millions of people with tens of thousands of deaths. Risk for more severe outcomes is greater among the youngest and oldest patients, those who are pregnant, and patients with underlying chronic health conditions. Symptoms frequently resemble other respiratory illnesses, which makes clinical diagnosis challenging. Most people can infect others beginning one day before symptoms develop, posing a challenge for many infection prevention and control strategies. The most effective prevention strategy is annual vaccination; however, vaccine effectiveness can vary among influenza seasons, for different influenza types, and depending on the ages of vaccine recipients. Annual vaccination is required because frequent genetic mutations of the virus can cause immunity to rapidly wane. Pandemics have occurred multiple times during the past century after different influenza viruses have combined genetic material to form a new virus. Surveillance and interventions for any identified issues are key infection prevention strategies to manage annual influenza epidemics and prevent facility transmission. Infection preventionists also serve a key role in preparing for future pandemics.