Background: Although children are less likely than adults to become infected by SARS-CoV-2, a widespread uncontrolled dysregulation of the host immune defense can occur at any age. We sought to investigate some potential immunological changes in confirmed pediatric COVID-19 in relation to disease severity and outcome. Methods: Our cross-sectional study comprised 55 confirmed COVID-19 pediatric cases, and 50 healthy matched control subjects. Patients underwent detailed clinical evaluation, laboratory immune system screening and radiological assessment. The laboratory testing included complete blood counting (CBC), serum immunoglobulins, lymphocyte immunophenotyping by flow cytometry and CD107a expression as a marker of natural killer cells degranulation .
Results: There were some disturbances in key lymphocyte subsets in the form of reduced levels of B cells (CD19), natural killer cells (CD56), CD4+ T cells, and CD8+ T cells. Impaired NK cell degranulation and cytotoxicity were evident as significantly decreased levels of CD107a in COVID-19 cases compared to controls (p<0.0001). Comorbid conditions and lymphopenia amplified the reduction in the studied lymphocyte subsets, CD4/CD8 ratios and the elevation of CD8 percentage. These immune impairments did not correlate with disease severity or ICU admission .
Conclusion: Significant immunologic changes in hospitalized pediatric patients with confirmed COVID-19 infection were demonstrated. These dysregulations were amplified by the presence of comorbidities and lymphopenia but not by disease severity and ICU admission. Further wider scale longitudinal studies are needed to validate our conclusions.