With influenza activity increasing nationwide, CDC said Monday that physicians should quickly treat suspected cases in high-risk patients. The agency said it has received reports of severe respiratory illness among young to middle-aged adults with H1N1pdm09 virus infection, including some that were fatal. Some of the patients tested negative by rapid influenza diagnostic test, and many were reportedly unvaccinated. According to CDC, clinicians should continue their efforts to get people vaccinated against influenza and promptly begin antiviral treatment of severely ill or high-risk patients if influenza is suspected or confirmed. High-risk patients include children aged younger than 2 years; adults aged 65 years and older; people with immunosuppression; people with chronic pulmonary, cardiovascular, renal, hepatic, or metabolic disorders, among others; and the morbidly obese.