This method is useful to compare multiple samples of a single patient, however, positive rates of detection are around 85.4%. The highest sensitivity for the tests are recorded two weeks after initial symptoms arise. This method can also determine infection status and identify recovered patients who can serve as human donors of plasma for critically ill patients.

University of California, Santa Cruz

Purified recombinant S/N proteins are immobilized to the surface of a multi-well plate to serve as capture antigens. The inactivated SARS-CoV-2 serum samples are placed with the antigen for the virus to promote binding to the antibodies. A secondary antibody serves as a label and binds to the viral antibodies to display a signal when a substrate is added (which can then be measured via photometry).
The samples collected are blood serum samples from patients.

ELISA

Dcruz, R. J., Currier, A. W., & Sampson, V. B. (2020). Laboratory Testing Methods for Novel Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). Frontiers in Cell and Developmental Biology, 8. doi:10.3389/fcell.2020.00468

Frontiers in Cell and Developmental Biology

Advantages of ELISA

The sensitivity indicate the chance of higher false negatives and false positives with this method. Negative results do not rule out infection or recovery, especially with those who have been in contact with individuals who have been positive. 

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