As of creation, the CDC does not have an official case mortality rate for H5N1 in the United States.

Case fatality rate estimates for prior influenza pandemics vary, but are typically less than 3%, even for the 1918 avian influenza pandemic. Attempts over the last 2 decades to model H5N1 mortality in a pandemic have given variable estimates, with some suggesting similar mortality rates to the 1918 influenza pandemic. Others predict higher rates, with one notable study from the Ontario health Department in 2008 suggesting that an HPAI H5N1 pandemic will have a higher mortality rate of 14-33%.

https://pubmed.ncbi.nlm.nih.gov/18477756/

The WHO’s mortality rate estimate is 60%.

https://www.who.int/news-room/questions-and-answers/item/influenza-h5n1