How Rapid Lateral Flow Tests Work
A rapid antigen test is also known as a lateral flow test gives you quick test results within 15-20 minutes.
By Dr. JODIE MOSS
A rapid antigen test is also known as a lateral flow test gives you quick test results within 15-20 minutes. This type of test is a self-test that uses a sterile swab stick that has a cotton bud tip to swab the inside of your nose.
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Rapid antigen tests use immunoassay technology using nitrocellulose membrane, coloured nanoparticles, and typically antibodies to produce results. In your test device, there is a sample pad which when the solution is added onto the test device this pad will absorb the solution containing the virus fragments. The virus fragments are then absorbed and move along the strip and reach a set of labelled antibodies that are in the sample pad. These labelled antibodies are antibodies that are linked to either a visible label or marker which results in seeing what the antibodies bind to. These labelled antibodies recognise certain parts of the viral fragments (if any are present) and will bind to them strongly. Once this process has taken place, they will move along the sample pad to the test zone. In the test zone, there is a line of fixed antibodies that will also recognise and bind to the virus fragments. Unattached antibodies will continue on to the control bed and produce a line across the control area. The control line (C) shows that the test has worked and that this test result is valid. A colour line will appear across the test zone (T) if the virus is present – two lines represent that at the time of testing you have coronavirus (COVID 19).
Steps on how to perform your rapid antigen test:
Step 1: Before you start your test wash your hands with soap and water or by using an alcohol-based gel. Then blow your nose into a tissue to get rid of any nasal discharge.
Step 2: Lay all the items of your test kit out on a flat surface. Remove the test device from the foil pouch and ensure that your test kit has not been damaged.
Step 3: Remove the sterile swab from its sheath by pealing it back and carefully removing it.
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Step 4: Tilt your head back slightly
Step 5: Insert the swab stick into one of your nostrils until you feel some slight resistance rotate the swab 4 to 6 times for at least 15 seconds to collect your sample. Remove from your nostril and repeat this same action in the other nostril.
Step 6: Open the sample tube which contains a solution by twisting the top and insert the swab stick into the tube. Rotate the swab stick at least 5 times (15 seconds) and then slightly lift the swab stick out of the solution. Before you remove, the swab stick from the tube squeeze the tube around the swab cotton bud to remove as much of the sample from the swab stick. Remove the swab stick fully and close the lid.
Step 7: Place 3 drops of the solution into the specimen well on the test device.
Step 8: Wait 15 minutes before you read your result.
A Positive Test result will display two lines on the test device.
A Negative Test result will display one line on the control area (c).
An Invalid Test result will display no lines on the test device.