Clinical Treatment Research of COVID-19-related Olfactory Dysfunction

Inclusion Criteria: 1\. Previous diagnosis of COVID-19 infection; 2. Olfactory function was normal in the past, and the olfactory function decreased due to COVID-19 infection, which has occurred more than 2 weeks; 3. Olfactory function test score: TDI ≤ 30; 4.18 ≤ age ≤ 55 years old; 5.Good overall physical condition, without other diseases that may affect the test; 6. No active infection, such as uncontrolled pneumonia; 7. Women with reproductive potential and sexually active men agree to use acceptable and effective contraceptive methods. Exclusion Criteria: 1\. Participants who refuse to sign informed consent; 2. Participants who have other diseases that affect the result, such as trauma, benign and malignant tumors of nasal cavity and paranasal sinuses, intracranial benign and malignant tumors, etc; 3. Participants with uncontrolled concurrent diseases that the researcher believes will interfere with the treatment; 4. Participants who has contraindications to oral corticosteroids, such as serious gastric and duodenal ulcer, diabetes, glaucoma, etc; 5. Participants who have serious neurological or mental diseases, including dementia and seizures; 6.Participants who have oral corticosteroids history within 2 weeks, or who have recently taken a large amount of oral corticosteroids and are not suitable after the evaluation of the researcher; 7. Participants who have used corticosteroids therapy during the treatment of COVID-19 and olfactory function didn't recover; 8. Pregnant or lactating women; 9. persons without personal freedom and independent civil capacity; 10. Participants who have been enrolled in other intervention clinical trials; 11. Participants who with autoimmune diseases; 12. Participants who has any situation that may hinder the compliance of the protocol study or the safety during the study; 13. Other situations that the investigators think are not suitable for the trial.