What to know about a COVID-19 antigen test

Antigen tests work by detecting proteins from SARS-CoV-2 in a sample, often collected from the nose. A positive result can support a diagnosis when the test is used correctly, while a negative result can be less reassuring early in illness or when the sample is inadequate. Read the instructions for the specific kit, check its expiry information, and do not interpret a faint or unclear result without advice from the provider or manufacturer.

Follow the kit instructions closely and record when the sample was taken, your result, and any symptoms. If positive, reduce close contact and follow current local guidance. If negative but you have symptoms or a recent exposure, consider repeat testing or a more sensitive test according to clinical advice. Contact a clinician promptly if you have medical conditions that raise the risk of severe illness, since treatment options can be time-sensitive.

Get emergency help for severe breathing difficulty, persistent chest pressure, new confusion, inability to wake, collapse, or blue or grey lips. Seek prompt assessment if symptoms worsen despite a negative test, if you cannot keep fluids down, or if fever and weakness are becoming more severe. A test result should never delay urgent care.

Ask whether your result needs confirmation, when to repeat testing, how long to avoid close contact, and whether your symptoms warrant treatment or assessment for complications.