Influenza viral infections: presentation, prevention, and treatment.

Each year, 20,000 to 40,000 people in the United States die of influenza and associated complications. Influenza infections account for several billion dollars in health care expenditures each year. Two important measures to minimize the incidence of influenza infection are vaccination and chemoprophylaxis with antiviral agents. Vaccinations must be given annually for two reasons: the antigenic changes that influenza strains, particularly influenza A, undergo and the diminished antibody response that occurs over time. Specific efforts should be targeted to high-risk groups. The adverse effects of the vaccine are generally mild, with a sore arm being the most common complaint. Chemoprophylaxis is the recommended substitute for vaccination in people with egg allergy. The vaccine is effective 70% to 90% of the time in preventing illness in healthy individuals. Unfortunately, less than 30% of the targeted population receives the vaccination each year. More research must be conducted on ways to improve the organization and administration of influenza vaccinations.