Influenza: Optimizing Prevention and Treatment Strategies
Knowledge of the natural history of influenza is important for understanding the ongoing significance of the influenza vaccine. Influenza is an RNA virus with three antigen types: A, B, and C. Most clinical illness is caused by types A and B. Influenza A is also associated with subtypes based on two surface antigens: hemagglutinin, which is responsible for viral attachment to cells, and neuraminidase, which is responsible for viral penetration into cells. The genetic change of these surface antigens over time leads to antigenic shifts and drifts that, if transmitted from person to person, can result in a pandemic or epidemic, respectively. Influenza epidemics and pandemics that resulted in millions of deaths and caused widespread respiratory illness have been documented as far back as the 1500s. The last major pandemic seen in the U.S. was the novel influenza A(H1N1) virus in 2009.
Influenza is typically most prevalent during the fall and winter months. The CDC publishes weekly surveillance data indicating the prevalence of influenza illness across the U.S., as well as additional information on influenza-related deaths, hospitalizations, antigenic characterization, and antiviral resistance patterns.
History
Knowledge of the natural history of influenza is important for understanding the ongoing significance of the influenza vaccine. Influenza is an RNA virus with three antigen types: A, B, and C. Most clinical illness is caused by types A and B. Influenza A is also associated with subtypes based on two surface antigens: hemagglutinin, which is responsible for viral attachment to cells, and neuraminidase, which is responsible for viral penetration into cells. The genetic change of these surface antigens over time leads to antigenic shifts and drifts that, if transmitted from person to person, can result in a pandemic or epidemic, respectively. Influenza epidemics and pandemics that resulted in millions of deaths and caused widespread respiratory illness have been documented as far back as the 1500s. The last major pandemic seen in the U.S. was the novel influenza A(H1N1) virus in 2009.
Influenza is typically most prevalent during the fall and winter months. The CDC publishes weekly surveillance data indicating the prevalence of influenza illness across the U.S., as well as additional information on influenza-related deaths, hospitalizations, antigenic characterization, and antiviral resistance patterns.