Rapid antigen tests allow for convenient self-screening for COVID-19. These kits detect specific viral proteins (antigens) in a respiratory sample, providing results much faster than laboratory tests. Although exact instructions vary slightly between brands, the foundational steps for sample collection and result interpretation are largely the same. Understanding this common process empowers individuals to use these home tests effectively for personal and public health screening.
Preparing the Testing Area and Materials
Before testing, prepare a clean environment and confirm the kit’s viability. Start by thoroughly washing your hands with soap and water for at least 20 seconds, then dry them completely. Select a flat, stable surface that can be easily sanitized afterward, ensuring it is free from dust or contaminants that could affect the sample.
Inspect the test kit to verify all components are present and undamaged. Confirm the expiration date has not passed, as expired tests may yield unreliable results. Lay out the parts—including the sterile swab, buffer solution tube, and test cassette—without touching the soft tip of the swab or the cassette’s result window. Reading the manufacturer’s specific instructions helps prevent errors, as the exact timing or number of solution drops can vary.
Detailed Instructions for Sample Collection
The accuracy of the rapid antigen test depends significantly on obtaining a quality sample. Begin by gently blowing your nose to clear excess mucus, which helps ensure the swab makes contact with the nasal lining cells. Carefully insert the soft end of the swab into one nostril, about one-half to three-quarters of an inch deep, which is less invasive than a deep nasopharyngeal collection.
Once inserted, gently rub and rotate the swab against the inside wall of the nostril four to five times, or for five to ten seconds, to collect viral material. Use the same swab to repeat this process in the second nostril. Immediately process the sample by placing the swab tip into the extraction buffer solution tube.
Swirl the swab tip vigorously in the liquid, often for 10 seconds, while pressing the outside of the tube against the swab to release the sample. Remove the swab, typically by pinching the tube to squeeze out remaining fluid, and then discard it. Finally, add the required number of drops (often three) from the buffer tube into the designated sample well on the test cassette, avoiding air bubbles, and set a timer immediately.
Understanding and Reading Your Results
Interpreting the result requires strict adherence to the waiting time specified in the instructions. Most rapid antigen tests must be read between 15 and 30 minutes after the drops are placed into the cassette. Reading the test too early may produce a false negative, while reading it after the maximum time may show a misleading positive line.
The test cassette displays two potential lines: the Control (C) line and the Test (T) line. A negative result is indicated by the appearance of the Control (C) line alone, with no line visible next to the Test (T) marker. This means the test functioned correctly, but viral antigens were not detected.
A positive result is confirmed when both the Control (C) line and the Test (T) line appear. The intensity of the Test line does not matter; any visible line, even a faint one, is interpreted as positive. If the Control (C) line does not appear, regardless of the Test (T) line presence, the result is invalid. This means the test did not work and must be repeated with a new kit.
Actions to Take Based on Test Outcome
A positive result means the virus was detected, and you should immediately take steps to prevent further transmission. Public health recommendations advise immediate isolation for at least five days, starting from the day symptoms began or the positive test date. Wear a high-quality mask when around others in your home, use a separate bathroom if possible, and avoid sharing household items.
People who test positive should contact a healthcare provider, especially if symptomatic, to discuss potential treatments that work best when started early. You can typically return to normal activities after five days if symptoms are improving and you have been fever-free for 24 hours without medication. Wearing a mask is often recommended for the subsequent five days.
A negative result does not guarantee the absence of infection, as these tests are less sensitive than laboratory tests. If you have symptoms but test negative, or if you were recently exposed, repeat testing is recommended.
Repeat Testing Guidance
The FDA suggests the following protocols for repeat testing:
- Individuals with symptoms who test negative should test again 48 hours later.
- Individuals without symptoms should test a total of three times over five days, with 48 hours between each test.
If you receive an invalid result, all testing materials must be properly sealed and disposed of, and a new test must be performed immediately using a fresh kit.