An at-home COVID-19 test, commonly known as a rapid antigen test, detects proteins from the SARS-CoV-2 virus, indicating an active infection. These tests offer quick results, typically within 15 to 30 minutes, using a shallow nasal swab sample. While convenient, their accuracy is generally lower than laboratory-based PCR tests, making proper execution of the procedure important. A positive result is highly reliable, but a negative result, especially with symptoms, may require follow-up testing.
Essential Preparation Steps
Read the specific instructions provided with your test kit, as minor variations exist between brands. Check the expiration date on the box to ensure the chemical reagents have not degraded, which could lead to inaccurate results. If stored in a cool environment, bring the test kit components to room temperature (generally between 59 and 86 degrees Fahrenheit), as temperature extremes can affect performance.
Hygiene is essential to prevent contamination of the sample. Wash your hands thoroughly with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer, and dry them completely. Lay out the swab, the extraction buffer tube, and the test cassette on a clean, flat, well-lit surface. Have a timer ready, since the timing of the final steps is precise.
Step-by-Step Sample Collection
Carefully remove the sterile collection swab from its packaging, touching only the handle and avoiding the soft collection tip. Before swabbing, gently blow your nose into a tissue to clear excess mucus, which helps ensure a better sample. The swab is designed for a shallow nasal collection, not a deep nasopharyngeal one, so the process should not be painful.
Insert the swab tip into one nostril, going no more than about three-quarters of an inch deep. Gently rub and rotate the swab against the inner wall in a circular motion, completing at least four to five full rotations for a minimum of 15 seconds. Use the same swab to repeat this entire process in the second nostril to maximize the viral material collected.
Transfer the collected sample immediately to the extraction buffer tube, which contains liquid designed to release the viral antigens. Insert the swab tip into the liquid and stir it vigorously, typically 10 to 15 times, pressing the swab against the bottom and sides of the tube. As you remove the swab, pinch the sides of the tube firmly against the tip to extract as much liquid as possible. Insufficient liquid transfer can lead to an inaccurate result. Discard the used swab, seal the tube with its cap, and the sample is ready for the test cassette.
Interpreting and Acting on Results
Apply the prepared liquid to the test cassette. Open the small cap on the tube and dispense the specified number of drops, usually three to five, into the designated sample well, often marked with an ‘S’. Immediately start a timer for the duration specified in the instructions, typically between 15 and 20 minutes.
Read the result within the time window specified by the manufacturer. Lines appearing after the maximum time limit (often 30 minutes) can be misleading and lead to a false positive. The test result window displays two lines: the Control line (‘C’) and the Test line (‘T’). A valid test must always show a line next to the ‘C’ to confirm the test worked correctly.
A negative result is indicated by only the ‘C’ line appearing, with no line next to the ‘T’. If symptomatic, a negative antigen test should be followed by a repeat test after 48 hours or a more sensitive PCR test. A positive result is indicated by a line next to both the ‘C’ and the ‘T’. Even a faint line next to the ‘T’ counts as a positive result, indicating the presence of the viral antigens.
Anyone who receives a positive result should immediately follow public health guidelines, which typically include isolating to prevent further transmission. Contact a healthcare provider to discuss next steps, especially if you are at a higher risk for severe illness and may be eligible for specific treatments. Once the testing is complete, seal all used materials in a plastic bag before disposal to safely contain biohazardous waste.