Pandemic influenza vaccines

In April 2009, a new influenza A (H1N1) virus, was determined to be the cause of outbreaks of respiratory illness in the United States of America and Mexico. In contrast to seasonal influenza, current evidence indicates that relatively few severe cases of novel influenza A (H1N1) virus infection have occurred among older persons, and the highest hospitalization rates for illness caused by this virus have been among persons aged 65 years. Although the signs and symptoms of novel influenza A (H1N1) virus infection are similar to those of seasonal influenza, specific diagnostic testing is required to distinguish novel influenza A (H1N1) virus from seasonal influenza virus. Influenza vaccination is the most effective method for preventing influenza and influenza-related complications.