FPJ Interview: For accurate COVID-19 self-test result, adhere to basic hygiene protocols, says doctor

Are home Covid testing kits reliable?

With a rise in coronavirus cases, the demand for home test kits has increased tremendously in the third wave. While rapid home tests give prompt results, molecular PCR testing is said to be more accurate.

How should one use the home testing kit?

Download the application mentioned on the kit and fill in your credentials. Sanitise your hands before using the kit and find a clean surface to place it on. Tear the Covid testing pouch and lay it down on the clean surface. Ensure that you take the test within 30 minutes after opening. Tap the pre-filled extraction tube to settle the liquid. Open the sterile nasal swab and make sure you do not touch it. Insert the nasal swab in both nostrils one after the other up to 2-4 cm. Roll the swab five times in each nostril. Immerse the swabs in the prefilled extraction tube and break them. Cover the tube with the nozzle cap. Note that any result that appears post 20 minutes will be considered invalid.

What factors can contribute to a false negative/ positive or invalid status? One should adhere to the basic hygiene protocols or the test can become contaminated and the results may not be accurate.

How to detect a false negative/ positive?

Home testing kits are swift in delivering results and cost-effective, but one can’t say that they are 100 per cent accurate. A kit either shows two lines next to the letters C and T suggesting a positive result or displays only one line next to C, suggesting a negative result. However, if you notice very faint lines on the device, you might find it difficult to interpret them and chances of a false negative or positive may be high. The interpretation window is very important.

If any line appears before the end of the window, which is usually 20 minutes, whatever the result maybe it is possibly accurate and one is advised to isolate. However, if the line appears after the window, this does not count as a positive /negative test. Therefore it is of paramount importance to read the results within the allotted window. For most tests, it is 30 minutes, but some might have a shorter window of 15 minutes.

(Dr Prem is a consultant at the department of geriatric medicine, Jaslok hospital and research centre)