Inclusion Criteria:  Significant sputum production (≥ 10 ml per day) Adult patients aged 18 years or older of both sex and diagnosed as COVID-19 positive by PCR either during same visit or in previous visits during the 2020-2021 who have CT scan examination of the chest during acute diseases or at follow up  Exclusion Criteria:  Children under 18 years old, patients with known chronic chest diseases, and patients who are not examined by CT scan of the chest