[New pandemic influenza: what are the risks?]

Area of Science:

• Virology
• Epidemiology
• Public Health

Context:

• Influenza pandemics originate from novel avian influenza A subtypes entering the human population.
• Avian influenza A viruses require significant adaptation to become transmissible between humans.
• Two primary adaptation mechanisms include direct mutation accumulation and genetic reassortment with human influenza viruses.

Purpose:

• To assess the pandemic potential of avian influenza A(H5N1) virus.
• To evaluate the risk posed by the current A(H5N1) strain given its observed human cases and widespread epizootic spread.
• To identify the factors contributing to the pandemic threat of A(H5N1).

Summary:

• Influenza pandemics emerge from new avian influenza A subtypes.
• The avian influenza A(H5N1) virus, despite not being human-adapted, has caused 382 human cases with 241 deaths.
• Widespread avian A(H5N1) outbreaks, human infections from poultry exposure, and poor control in bird populations highlight its pandemic risk.

Impact:

• Understanding avian influenza A virus adaptation is crucial for pandemic preparedness.
• The current A(H5N1) strain represents a significant threat for a future influenza pandemic.
• Effective control of A(H5N1) in avian reservoirs is essential to mitigate pandemic risk.