Inclusion Criteria:  age above 18 years covid-19 patients (20) with real time PCR positive test moderate to severe according to CDC classification smokers are included post-covid 19 patients with real-time pcr positive test 20 healthy subjects  Exclusion Criteria:  below 18 years and above 80 years pregnant womens any medications as anti-il-6 unstable cases history of copd cases or lung disease or lung cancer