Description
This laboratory test quantitatively measures the SARS-CoV-2 nucleocapsid (N) protein in peripheral blood mononuclear cells (PBMCs).
PBMCs include monocytes and lymphocytes, which may internalise viral proteins during or following infection. After isolation and controlled cell processing, intracellular nucleocapsid protein is analysed using an immunoassay-based detection method to quantify measurable antigen within the sampled cell population.
The assay detects nucleocapsid protein present within the isolated immune cells at the time of sampling. Protein that has been fully degraded, processed into small peptides, present in unsampled tissues, or below the analytical detection limit may not be measurable.
Because currently authorised spike-based COVID-19 vaccines do not contain the nucleocapsid protein, detection is generally associated with prior or ongoing exposure to viral material rather than vaccination alone.
While the test identifies the presence of nucleocapsid protein, it cannot determine the exact timing of infection or the specific viral variant.
Test results should always be interpreted together with clinical symptoms, medical history, and other laboratory findings.