And it isn't "just the flu".
https://www.bmj.com/content/bmj/371/bmj.m4677.full.pdf
"In sum, our results suggest that compared with patients admitted to hospital with seasonal influenza, those admitted with covid-19 have increased risk of systemic clinical manifestations (including higher risk of acute kidney injury, incident renal replacement therapy, incident insulin use, severe septic shock, vasopressor use, pulmonary embolism, deep venous thrombosis, stroke, acute myocarditis, arrythmias and sudden cardiac death, elevated troponin, elevated aspartate aminotransferase, elevated alanine aminotransferase, and rhabdomyolysis), increased risk of death, and higher need for healthcare resources (mechanical ventilation, ICU admission, length of hospital stay)."