Fig. 3

Comparison of the hazards of life-threatening secondary infections in COVID-19 and seasonal influenza patients. *Cox models were stratified by matching identifier (sex, birth year, Charlson comorbidity index, and decile of Townsend deprivation index) and adjusted for education level, Townsend deprivation index (as a continuous variable), Charlson comorbidity index (as a continuous variable), BMI, smoking status, and history of life-threatening infections; ^#for all life-threatening secondary infections, the exposed individuals were stratified into three subgroups: with hospital admission and operations/procedures, with only hospital admission, and with neither hospital admission nor operations/procedures, along with their matched unexposed individuals; ^$defined as having been discharged at the time of the life-threatening secondary infection diagnosis, and we also required that a diagnosis of prior virus infection was not present during the hospitalization of the subsequent severe secondary infections