The recent news about the accuracy of self test kits/antigen rapid test kits (RTK-AG) has sparked further debate. For example, a few days ago, some netizens claimed that they used these kits every day for testing, as well as up to five different brands of rapid test kits, and that the results were all negative. When they eventually used the PCR test, they were surprised to learn that they had been diagnosed with the infection.
In fact, these antigen rapid test kits (RTK-Ag) are inherently less accurate than polymerase chain reaction (RT-PCR), and may lead to inaccurate results in these three circumstances. These are some of them:
1. The self-test kit’s accuracy and flaws
Rapid test kits are less accurate than polymerase chain reaction (PCR) and come with their own set of constraints. For example, some brands of rapid tests can detect the coronavirus with a cycle threshold (CT value) of less than 30. If the CT value of the diagnosed person is higher than this index, the test results will be changed.
2. Error handling by the user
Different brands of rapid tests have different methods. The public is urged to read the instructions carefully before using them. Also, avoid doing the following in the hour leading up to the saliva test: eating, smoking, brushing, chewing gum, gargling with mouthwash or salt water, and so on. Inadequate saliva sample collection might also result in inaccurate test results.
3. Detection period
Viruses have a period of incubation. If you’ve recently been infected with the virus, the amount of antigens in your sample is probably too small to detect. Alternatively, the body has progressively recovered after 7 days of infection, and the number of antigens in the sample is too low to be detected. The test should be done on the fourth or fifth day after contact with a confirmed patient, and the result will be more accurate.
