biochemical marker; CD19 antigen; CD3 antigen; CD4 antigen; CD8 antigen; endogenous compound; receptor type tyrosine protein phosphatase C; adult; bacterial pneumonia; blood cell count; blood sampling; CD4 lymphocyte count; CD8 lymphocyte count; clinical article; conference abstract; controlled study; coronavirus disease 2019; female; flow cytometry; follow up; gender; hospital discharge; human; human cell; leukocyte; lymphocyte; lymphocyte count; lymphocyte subpopulation; lymphocytopenia; male; neutrophil; neutrophil lymphocyte ratio; neutrophilia; outcome assessment; prognosis; receiver operating characteristic; software; T lymphocyte