H7N9: preparing for the unexpected in influenza

Area of Science:

• Virology
• Epidemiology
• Public Health

Background:

• Avian influenza A H7 viruses typically caused mild human illness before 2013.
• A novel influenza A(H7N9) virus emerged in China in March 2013, causing severe human illness and high mortality.

Purpose of the Study:

• To characterize the novel influenza A(H7N9) virus.
• To assess the risk of further adaptation and human-to-human transmission.

Main Methods:

• Genetic sequencing
• Glycan-array receptor-binding assays
• Ferret studies
• Risk-assessment tools
• Virologic and epidemiologic surveillance

Main Results:

• The H7N9 virus demonstrated increased binding to mammalian respiratory cells.
• Mutations were identified, correlating with higher virus replication rates and increased illness severity.
• Risk assessment indicated potential for further mammalian adaptation and human-to-human transmission.

Conclusions:

• The novel H7N9 influenza virus poses a significant public health threat due to its severity and potential for adaptation.
• Ongoing virologic and epidemiologic surveillance is crucial for monitoring H7N9 and detecting emerging novel influenza viruses.