Background: Study of expression of lymphocyte subsets could help to understand the pathophysiology of COVID-19 infection, development of novel treatment protocols and reducing rate of mortality among COVID-19 infected patients.

Objective: The aim of this work was to correlate expression of lymphocyte subsets with the inflammatory markers and clinical status of patients with COVID-19 infection.

Patients and methods: This prospective study was performed at Zagazig University Isolation Hospitals and clinical pathology department, Zagazig, Egypt on 80 persons who were enrolled in this study; 40 COVID-19 patients with pneumonia made up group I, and the following individuals made up group II: 40 COVID-19 patients without pneumonia. Immunophenotyping of CD4 CD8 were measured by Flow Cytometry in both groups.

Results: Patients had a considerable drop in CD4 CD8 levels with pneumonia than those without pneumonia

Conclusion: Low levels of CD4 CD8 in COVID-19 patients are associated with a higher risk of pneumonia.