Sentence: Patients with major comorbidities had high viral RNA concentration even when presenting 12 days after symptom onset ( mean ע standard deviation , vs log 10 copies/mL ; ; b , +0.86 ( 95 % confidence interval , 5.06 ע 1.85 3.62 ע 2.13 P p .005 +0.03 to +1.68 ) ). 
 Section: purpose