Summary of Influenza Risk Assessment Tool (IRAT) Results

The H5N1 bird flu viruses that are causing outbreaks in wild birds and poultry, occasional infections in mammals, and rare human infections are H5N1 clade viruses. A risk assessment for the potential ‘emergence’ and ‘public health impact’ for those viruses was conducted in March 2022 using A/American wigeon/South Carolina/AH0195145/2021. New information available since then, including from 7 additional human cases, is being used to inform an updated assessment. A new report is being prepared and will be posted when complete.

The Influenza Risk Assessment Tool (IRAT) is an evaluation tool conceived by CDC and further developed with assistance from global animal and human health influenza experts. The IRAT is used to assess the potential pandemic risk posed by influenza A viruses that are not currently circulating in people. Input is provided by U.S. government animal and human health influenza experts. Information about the IRAT is available at Influenza Risk Assessment Tool (IRAT) Questions and Answers.

Virus Descriptions and Report Summaries

Summary Results of Influenza A Viruses Assessed Using IRAT

Below is a table of results for influenza A viruses that have been assessed using IRAT because the viruses serve as a representative of a particular virus subtype or are of unique interest.

Note: The letters in the ‘dot’ column of this table correspond to those in the dot graph above.

IRAT Virus Emergence and Impact