Antigenetesti

Antigenetesti, or antigen test, is a rapid diagnostic method that detects specific proteins from a pathogen, most commonly viral proteins from SARS-CoV-2 or other respiratory viruses. It is used to identify current infection by detecting viral antigens in samples from the upper respiratory tract.

Most antigen tests are immunoassays that use antibodies to capture viral antigens. The common format is a lateral flow assay, producing a visible line within minutes, similar to a home pregnancy test. Specimens are usually nasal or nasopharyngeal swabs, though some assays can use saliva.

Usage and interpretation: They are used for rapid screening at clinics, workplaces, schools, or at home where permitted. A positive result generally indicates infection, while a negative result should be interpreted in context; if symptoms persist or exposure is recent, a confirmatory RT-PCR test may be recommended. Timing matters; they work best during higher viral loads.

Performance and limitations: Sensitivity is generally lower than RT-PCR, particularly in asymptomatic individuals or late in infection; specificity is typically high, but false positives can occur, especially in low-prevalence settings. Test performance depends on timing relative to symptom onset, specimen quality, and adherence to the manufacturer's instructions. Regulatory status varies by country, with some tests approved for home use.