The epidemic has been geographically focused in China, and is associated with exposure to infected poultry.
The risk to public health is low; however, the pandemic potential of this virus is concerning. Case clusters of limited human-to-human transmission have been described, but there is no evidence of sustained transmission.
Infection prevention and control measures for routine care include standard, droplet, and contact precautions. Particulate respirators are recommended for aerosol-generating procedures.
There is a high cumulative case-fatality proportion of approximately 40% among hospitalized patients with laboratory-confirmed infection.
Reverse transcription-polymerase chain reaction of respiratory tract samples is the recommended diagnostic test.
Treatment involves supportive care, specialized intensive-care management, and administration of a neuraminidase inhibitor.
Avian influenza A viruses are generally confined to birds but have infected other mammals and some viruses have crossed the species barrier to sporadically infect humans. Highly pathogenic avian influenza (HPAI) A(H5N1) virus is capable of causing severe multisystem disease in birds, humans, and other mammals.  Until 2017, Asian lineage A(H7N9) virus infections in birds were associated with only asymptomatic infection or mild illness (characterized as low-pathogenicity avian influenza; LPAI). In February 2017, the detection of Asian lineage HPAI A(H7N9) viruses was reported for the first time in the People’s Republic of China (herein referred to as China), in samples from human cases, and from poultry and their environments.   Regardless of pathogenicity assessments in birds, Asian lineage LPAI A(H7N9) virus typically causes severe illness in infected humans. 
Following the detection of Asian lineage LPAI A(H7N9) virus infection in humans in eastern China in March 2013, A(H7N9) viruses that are genetically similar to isolates from human cases were detected in poultry and environmental samples obtained from live animal markets in China.   Investigation of isolated clusters of human infections where zoonotic transmission was thought to be unlikely suggests that human-to-human transmission may occur with Asian lineage LPAI A(H7N9) viruses, although transmission appears to be limited and nonsustainable.     Nosocomial transmission, including patient-to-healthcare worker, and patient-to-patient, has been reported for Asian lineage LPAI A(H7N9) viruses.   
Consultant in Infectious Diseases and General (Internal) Medicine
Respiratory Virus Unit
Virus Reference Department
National Infection Service
Public Health England
JD declares that he has no competing interests.
Assistant Professor of Medicine and Global Health
International Respiratory and Severe Illness Center (INTERSECT)
Division of Pulmonary and Critical Care Medicine
University of Washington
JRO declares that he has no competing interests.
Chief Medical Officer
National Center for Immunization and Respiratory Diseases
Centers for Disease Control and Prevention
TMU declares that he has no competing interests.
To be added
RF declares that he has no competing interests.
Division of Infectious Diseases
Faculty of Medicine and Dentistry
University of Alberta
NL declares that he has no competing interests.
Division of Infectious Diseases
Division of Organ Transplantation
Northwestern University Feinberg School of Medicine
MI declares that he received research support, paid to Northwestern University, from Beckman Coulter, Chimerix, and Gilead; is a paid consultant for Celltrion, Chimerix, Farmark, Genentech/Roche, Toyama/MediVector, Seqirus, and Shionogi; and is a member of the DSMB for GlaxoSmithKelin and Shionogi.
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