This study examined patients hospitalized with influenza who developed a serious fungal infection caused by Aspergillus fungus. Among 109 influenza patients, about 9% developed this fungal complication which significantly increased their risk of death and required longer hospital stays. Patients with existing lung diseases were at higher risk, and those with the fungal infection also had more bacterial superinfections. The findings highlight the importance of recognizing and treating this serious fungal complication in hospitalized influenza patients.