An antigen rapid test is a quick diagnostic tool designed to detect specific proteins, known as antigens, that are located on the surface of a virus. These tests are a type of lateral flow assay, which uses a paper-based platform to quickly identify the presence of a pathogen in a sample. The primary purpose of this test is to provide rapid, point-of-care screening for an active infection, delivering results much faster than traditional laboratory-based methods. The result indicates whether the target antigen is present at a detectable level at the time the sample was collected.
Essential Pre-Test Preparation
Ensure all components are ready and conditions are optimized for accuracy before starting the test. Check the expiration date printed on the box, as using an expired kit can produce unreliable results. Verify that all necessary parts—the sterile swab, the buffer solution tube, and the test cassette—are present and undamaged.
The entire kit, especially the buffer solution, should be at room temperature (generally between 2°C and 30°C) to ensure the chemical reactions occur as intended. Hand hygiene is paramount; thoroughly wash your hands with soap and water for at least 20 seconds, or use an alcohol-based sanitizer, before handling the materials. Set up the equipment on a clean, flat surface and have a timer ready, as precise timing is necessary for both sample collection and result interpretation. Always review the manufacturer’s instructions, as these specific guidelines override any general advice.
Step-by-Step Sample Collection and Processing
Begin sample collection by gently blowing your nose into a tissue and discarding it, which clears excess mucus that could interfere with the test. Remove the sterile swab from its packaging, touching only the plastic handle and avoiding the soft tip. Insert the nasal swab straight back into one nostril for a shallow collection (typically 1.5 to 2.5 centimeters) until a slight resistance is felt.
Rotate the swab tip against the inner wall of the nostril, usually five to ten times, for approximately 15 seconds. Repeat the process using the same swab in the second nostril. Immediately submerge the tip into the extraction buffer solution, which is designed to break down the virus and release the antigen proteins.
Stir the swab vigorously while pressing the tip against the bottom or side of the tube to mix the sample thoroughly. Remove the swab while pinching the sides of the tube to squeeze out as much liquid as possible from the soft tip. Seal the extraction tube with the provided dropper cap, and dispense the specified number of drops (commonly three or four) into the designated specimen well on the test cassette.
Reading and Understanding Test Results
Once the sample is applied, the liquid analyte travels up the nitrocellulose strip via capillary action, carrying any viral antigens present. The test strip contains immobilized antibodies that capture the target antigens, forming a visible line. The test result must be read strictly within the time frame specified by the manufacturer, typically between 15 and 30 minutes.
A positive result is indicated by the appearance of two distinct colored lines: one at the Control (C) position and one at the Test (T) position. The presence of a line at the T position, even if very faint, suggests the target antigen has been detected. A negative result shows only one colored line, located solely at the Control (C) position.
An invalid result occurs if the Control (C) line does not appear at all, or if no lines appear on the cassette. The C line confirms that the test procedure was performed correctly and that the liquid sample migrated properly across the strip. Reading the cassette after the specified time window can lead to inaccurate interpretation, as evaporation may create a faint line that is not a true positive.
Reporting, Isolation Guidelines, and Safe Disposal
Following a positive result, immediately follow isolation guidelines to prevent further transmission. Consult local public health guidelines for the current recommended isolation period and for notifying close contacts. A negative test result, particularly in a symptomatic person, may require follow-up with a highly sensitive molecular test, such as a PCR test, for confirmation.
Local health authorities may require the reporting of positive self-test results; check regional guidelines for mandatory requirements. The used test kit components (the swab, cassette, and extraction tube) are considered potentially biohazardous waste because they contain biological material. For safe disposal, all components should be carefully sealed in a plastic bag.
It is recommended to double-bag the sealed contents before placing the waste into the household garbage. While many localities permit double-bagging for regular municipal disposal, always wash your hands thoroughly after handling and disposing of the used test materials.