For US adults ages 18-49, it varies (depending on the severity of flu strains) between .01% and .02%. https://www.cdc.gov/flu/about/burden/2016-2017.html https

For US adults ages 18-49, it varies (depending on the severity of flu strains) between .01% and .02%. https://www.cdc.gov/flu/about/burden/2016-2017.html https://www.cdc.gov/flu/about/burden/2016-2017.html