2.3. Study design
≥24-h
This was a randomized, open-label, single-center pilot study. Patients were observed for 4–5 days after hospitalization to exclude any severe cases of COVID-19, and then randomly divided into two group, i.e., the experimental group and the control group. The experimental group received regular care plus nasal irrigation and oral rinse with 5% sodium bicarbonate solution, while the control group received regular care only. Regular care refers to the treatment according to the “Diagnosis and Treatment Protocol for COVID-19 (Trial Version 9).” Oral rinse with sodium bicarbonate solution was conducted three times every day. Nasal irrigation was conducted two times in total. The solution entered through one nostril and exited from the other one, and the order of nostrils was changed on the second day. 30–40 mL of solution was used every time and the irrigation was performed for at least 30 s. Nasopharyngeal and oropharyngeal swab samples were collected from patients every day for RT-PCR tests. The specimen was considered positive if Ct (cycle threshold) values for both E and RdRP genes were smaller than 40, and the specimen was negative when no Ct value was obtained. If the RT-PCR results were negative, the patient would receive a second test after 24 h. The presence of two negative RT-PCR results, at ≥24-h intervals, was defined as viral clearance (