Influenza is a highly contagious viral illness characterized by fever, cough, headache and myalgia. The influenza virus is a segmented ribonucleic acid (RNA) virus that can infect both humans and animals, and the capacity for reassortment when multiple viruses infect the same cell has led – and will continue to lead – to the development of novel pandemic influenza A viruses. The disease is generally self-limiting, although complications and deaths can occur, particularly in children < two years of age, adults >65 years of age, pregnant women, and immunosuppressed individuals. Specific antiviral therapy is available, including oseltamivir in Singapore, and is recommended for severe disease as well as those with higher likelihood for developing complications from influenza. In addition to hand hygiene and respiratory etiquette, antiviral prophylaxis may reduce the impact and burden of influenza in household and institutional settings. However, the primary means for preventing influenza is via annual vaccination in those above the age of two years. The influenza vaccine, while having variable efficacy depending on antigenic matching with circulating viruses each year, is safe and cost-effective at the population level.