Novel reassortant H7N9 viruses were associated with severe and fatal respiratory disease in three patients. (Funded by the National Basic Research Program of China and others.).

Most persons with confirmed H7N9 virus infection had severe lower respiratory tract illness, were epidemiologically unrelated, and had a history of recent exposure to poultry. However, limited, nonsustained human-to-human H7N9 virus transmission could not be ruled out in four families.

No abstract