In February, 2013, a novel avian influenza A H7N9 virus emerged in east China and quickly spread to other areas. 1—3 By May 27, 130 human infections had been confirmed, with 37 deaths. Transmission can occur through direct or close contact with poultry or through exposure to environments that are contaminated with poultry. No human-to-human transmission has been reported. Co-infection of viruses in human beings, birds, or other animals provides the possibility for the emergence of a new reassortan ...