2.3 Laboratory tests
The SARS-CoV-2 viral nucleic acid detection on the pharyngeal swab specimens of each patient from the two hospitals were processed by technicians from Zhongnan Hospital of Wuhan University, using rRT-PCR assay.14 According to the recommendation issued by the National Institute for Viral Disease Control and Prevention (China),15 a cycle threshold value (Ct-value) less than 37 was defined as a positive test result, whereas a Ct-value of 40 or more was defined as a negative test. All rRT-PCR assays were performed with the same kit.
The complete blood counts, biochemical parameters and variables reflecting hepatic and renal functions on admission and data of follow-up laboratory tests during hospital stay were collected for each patient, including leucocytes and platelets, neutrophils, lymphocytes, monocytes, eosinophils, basophils, C-reactive protein (CRP), serum amyloid A (SAA), procalcitonin (PCT), D-dimer, serum creatine kinase (CK), creatine kinase-MB (CK-MB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN) and serum creatinine.
Serum and respiratory samples, such as pharyngeal swabs were used for detection of co-infected other pathogens, such as Mycoplasma pneumoniae, Chlamydia pneumoniae, Coxsackie virus group B, adenovirus, echovirus, respiratory syncytial virus, Epstein‐Barr virus, influenza A virus, influenza B virus, parainfluenza, cytomegalovirus, Gram-positive or Gram-negative bacteria, and fungi.