Eligibility Criteria
The indication for hospitalization according to the national protocol was as follows: fever above 39° or being toxic in the examination, respiratory distress, the use of respiratory muscle relaxants, the use of suprasternal or intercostal retraction, a respiratory rate greater than 30 per minute, a heart rate higher than 120 beats per minute, a peripheral blood O2 saturation level less than 93%, having an underlying disease (eg, diabetes, hypertension, heart failure, immune system disorders, renal or hepatic impairment, a history of asthma or chronic obstructive pulmonary disease, and smoking), age over 50 years in the case of being symptomatic, and the involvement of one-third of 3 to 5 pulmonary lobes. The exclusion criteria were composed of being a child, having unstable vital signs, being either intubated or needing intubation, being admitted to the ICU, having decreased levels of consciousness, having a respiratory rate greater than 24, having a blood pressure level below 90/60 mm Hg, exhibiting multi-lobular infiltration on CT scans or chest X-rays, having permanent hypoxia, being pregnant or lactating, and having previous allergies to NAC or glutathione-based drugs. The withdrawal criteria were comprised of drug intolerance, severe complications probably related to NAC during treatment, and unwillingness to continue collaboration with the study at any point and for any reason.