Patients with influenza admitted to a tertiary-care hospital in Riyadh between 2018 and 2022: characteristics, outcomes and factors associated with ICU admission and mortality.

Influenza followed a seasonal pattern in Saudi Arabia, with H3N2 and H1N1 being the predominant circulating strains during the study period. ICU admission was required for > 20%. Female sex, high Pneumonia Severity Index, ischemic heart disease, and immunosuppressed state were associated with increased mortality.