How reliable are home COVID tests?
Amid rising numbers of coronavirus cases, the demand for at-home COVID test kits has shot up significantly. While molecular PCR testing is said to be more accurate, rapid home tests are more prompt in delivering results, which is why many believe that it minimizes possibilities of delays and also eases the pressure of diagnostic labs.
However, while rapid tests have been seen as efficient, discussions around its accuracy and whether or not it can detect the new variant is ongoing. Let us first understand how home testing kits work.
How to use an at-home COVID testing kit?
The Indian Council of Medical Research has currently advised symptomatic individuals (who have been in close contact with COVID positive people) to use home testing by Rapid Antigen Test.
To use a self-test COVID kit, follow the below mentioned steps.
- Find a clean, sanitised surface to place your test kits.
- Wash your hands with soap and wipe it dry.
- Do not forget to download the app mentioned in the testing kit and fill in your credentials. Make sure you complete this step so no positive cases are missed.
- Tear the COVID testing pouch and lay it down on the clean surface. Ensure that you take the test within 30 minutes after opening.
- Gently tab the pre-filled extraction tube on the table for the liquid to settle.
- Unscrew the cap and hold it in your hand.
- While holding the tube in one hand, open the sterile nasal safe swab and do not touch the swab end.
- Slowly insert the nasal safe swap in both your nostrils one after the other up to 2-4 cms. Roll the swab five times in each nostril.
- Immerse the swab in the pre-filled extraction tube and break it where needed. Lastly, cover the tube with the nozzle cap.
Please see that any result that appears post 20 minutes will be considered invalid.
Mistakes to avoid
For those of you, who have never conducted an at-home COVID-19 test, make sure you read the instructions on the testing pouch and follow them accordingly. Make sure you let the swab sit for the required time and do not meddle with it.
It is of utmost importance that you wash your hands and sanitise them before conducting any test. If you do not adhere to these basic hygiene protocols, the test can become contaminated and the results may not be accurate.
What is a false positive/negative? How to detect it?
While at-home testing kits are swift in delivering results and cost-effective, it is not to say that they're 100 percent accurate. This suggests that there can be possibilities of getting wrong results i.e. a false positive or a negative.
A COVID test 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 COVID result. However, if you notice very faint lines on the testing device, you might find it difficult to interpret the same and chances of a false negative or positive may be high.
Read also: Coronavirus: Will my rapid antigen test or RT-PCR tell me if I have Omicron?
According to experts, the interpretation window plays a significant role in determining your test results. That said, if any line appears before the end of the interpretation window, which is usually 20 minutes, whatever the result may be, it is possibly accurate and one must isolate.
However, if the line emerges after the interpretation window, then this does not count as a positive/negative test.
Therefore, it is important to read the results within the allotted window. For most tests it is 30 minutes, although some may have a shorter window of around 15 minutes.
At-home antigen tests versus RT PCR COVID test: What's more accurate?
As compared to molecular or PCR testing, self-COVID tests may be a bit behind in terms of accuracy.
While at-home antigen tests may seem convenient, the chances of getting a false positive or negative is much higher with rapid tests than in a PCR test. The primary reason behind it is that the antigen test only looks at the protein part, and not the entire virus RNA. Rapid testing uses a technology that traces the protein in the virus strain and reveals whether a person is infected or not, whereas molecular testing helps detect the RNA, or the genetic component of the virus, which is likely to present the most accurate results.
So, in order to avoid any diagnostic mistakes, it is crucial that you take an RT PCR test.