Laboratory findings of SARS-COV-2 infection
The nucleic acid amplification test using RT-qPCR has become the gold standard for detection of SARS-CoV-2. Novel methods have been reported to enhance its efficacy and sensitivity27. IgG antibody assays against the receptor binding domain (RBD) and S1 domain were developed as an alternative diagnostic test, albeit with varying accuracies depending on the assay used28. Overall, antibody tests for SARS-COV-2 have high specificity but relatively lower sensitivity, which varied with different immunoassays and epitopes29. Antigen testing is inexpensive, can provide results in a few minutes and be performed at home. Population-wide antigen testing was demonstrated to reduce the transmission of SARS-CoV-230. Asymptomatic SARS-CoV-2 infection is associated with a longer duration of viral shedding and needs to be promptly detected to stop viral transmission31,32. The concentrations of neutrophil extracellular traps increase in the plasma, trachea aspirate and lung autopsies and contribute to the pathophysiology of COVID-1933,34. Thus, blood neutrophil extracellular traps can be a potential biomarker for SASR-CoV-2 infection. In addition, asymptomatic patients have lower levels of SARS-COV-2 specific IgG antibodies, which decay during the early convalescent phase31. Laboratory changes during COVID-19 have been reviewed and are summarized in our previous studies35,36.
Risk and protective factors for susceptibility, severity and mortality of COVID-19