Influenza: Prevention and treatment

Abstract

Influenza viruses cause annual epidemics of respiratory illness, and have caused three influenza pandemics since 1900. Although young children <2 years of age, adults >65 years of age and persons with underlying chronic medical conditions are at greatest risk for influenza complications, severe complications, including death, can occur in any age group. Influenza also results in a substantial amount of work and school absenteeism and losses in productivity. The diagnosis of influenza should be considered in persons presenting with respiratory symptoms or fever during periods when influenza virus is known to circulate locally, and influenza diagnostic testing is the only reliable way to differentiate influenza from other respiratory viral illnesses, which can present with the same constellation of symptoms. Annual influenza vaccination is the most effective way to prevent influenza and can provide protection against influenza even during seasons, where there is a suboptimal match between circulating influenza strains and the strains found in the influenza vaccine. Influenza vaccines are available in two forms: inactivated influenza vaccine and live attenuated influenza vaccine. Antiviral medications are an important adjunct to influenza prevention and control. However, the increasing prevalence of influenza viruses, that are resistant to currently licensed antiviral medications, highlights the need for the development of new antiviral medications. Some influenza viruses can infect many species of animals in addition to humans. Human infection with avian and swine influenza viruses is now well-documented, but modes of animal-human transmission and the burden of human infection with animal influenza viruses is still not well understood. In addition, an outbreak of novel swine-origin influenza A (H1N1) virus (S-OIV) was recently identified in many countries. The burden of disease resulting from S-OIV and its spread are still being characterized.