tissues(4) lymphopenia(4) Reinfection(4) previous study(4) asymptomatic infection(4) adopted(4) viruses(4) hydroxyl(4) Cell(4) envelope protein(4) phagocytic cell(4) Coronavirus pneumonia(4) superoxide anions(4) memory B cell(4) NK cell(4) water(4) cytokine(4) tissue(4) Novel coronavirus(4) surface antigen(4) domain(4) Asymptomatic(4) generate(4) infected cell(4) widespread(4) ROS(4) reactive oxygen specy(4) Lymphocytes(4) phagocyte(4) cell death(4)