The SARS-CoV-2 virus causes respiratory tract infection. It is transmitted mainly via respiratory droplets after close contact, and primary viral replication is presumed to occur in mucosal epithelium of the upper respiratory tract (nasal cavity and pharynx). At these locations viral load peaks within the first week after symptom onset, and then declines.
A CoV-2 antigen test detects the presence of the SARS-CoV-2 virus from part of the upper respiratory tract swab specimens by identifying a nucleoprotein that is carried by the virus. The test identifies current infection during the acute phase of COVID-19, while the virus is still present in large quantities in the respiratory tract.
Provider - Kudu Spectrum Health supplier to the NZ Government