Characteristics of Adults 50 years and older Hospitalized with Symptoms of Respiratory Illness or non-localizing Fever during 2006–2012 Influenza Season.

*defined as transplant, cancer within 5 years, diabetes, no spleen, heart or vascular disease, kidney or liver disease, sickle cell disease, asthma or chronic bronchitis or COPD or other lung disease, memory or thinking problems, HIV/AIDS or other problems with the immune system, genetic or metabolic disorders, neurologic disease, currently on prednisone or other steroids, any chemotherapy in the last 6 months, or any immunosuppressive medications in the last 6 months.Characteristics of Adults 50 years and older Hospitalized with Symptoms of Respiratory Illness or non-localizing Fever during 2006–2012 Influenza Season.