The goal of this type of clinical trial is to learn about symptomatic patients with post-COVID-19 parenchymal lung abnormalities. The main questions it aims to answer are: the efficacy and safety of low-dose dexamethasone or traditional Chinese medicine in symptomatic patients with post-COVID-19 parenchymal lung abnormalities.

Participants will be divided into three parallel groups：controlled group with conventional western medicine treatment including oxygen therapy, antibiotics, nebulization therapy, etc. dexamethasone group: dexamethasone 1.5mg/day for one week and 0.75mg/day for another week basing on conventional western medicine. Chinese medicine group: Strengthening spleen and tonifying lung decoction for 2 weeks basing on conventional western medicine.

Inclusion Criteria:

• Clinical diagnosis of COVID-19 pneumonia；
• 3 to 8 weeks after the onset of the first symptoms of COVID-19 infection;
• Modified Medical Research Council (mMRC) score ⩾2 or hypoxemia;
• Imaging severity assessment of pneumonia: CT severity scores (CTSS):≥5；
• Signed the informed consent.

Exclusion Criteria:

• Participants still admitted to intensive care unit at the time of enrollment;
• Known prior structural lung disease, including pulmonary fibrosis, severe COPD, severe bronchiectasis, and lung destruction;
• Taking glucocorticoids or immunosuppressants because of other chronic diseases;
• Contraindications of glucocorticoid;
• Heart failure(NYHA III or IV);
• Participants with renal replacement therapy;
• Psychiatric disorders or cognitive impairments;
• The expected survival time is less than six months due to diseases other than COVID-19 pneumonia.