H7N9 virus

Also known as: influenza A subtype H7N9

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Last updated

June 26, 2026

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The H7N9 virus is a subtype of the avian influenza A virus. It was first identified in humans in China in 2013 and can cause severe pneumonia and death. Bird flu viruses, including H7N9, are classified as orthomyxoviruses and are distinguished by surface proteins called hemagglutinin (H) and neuraminidase (N).1

While waterfowl are the primary hosts, these viruses can spread to domestic birds and then to humans, particularly those with close contact with infected birds. Symptoms in humans are similar to seasonal flu, including fever, cough, and muscle aches, but can progress to severe respiratory illness. The H7N9 strain has shown a high pathogenicity in humans, meaning it causes severe illness.1

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In 2013 a strain of H7N9 capable of causing severe pneumonia and death emerged in China, with the first confirmed cases detected in February that year and dozens more reported in the following months. It was the first H7N9 outbreak reported in humans.
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In 2013 a strain of H7N9 capable of causing severe pneumonia and death emerged in China, with the first confirmed cases detected in February that year and dozens more reported in the following months. It was the first H7N9 outbreak reported in humans.
Read More