RT PCR (reverse transcription polymerase chain reaction) is a testing technique wherein RNA template is used for detection and amplification of viral RNA. By using reverse transcriptase, RNA is converted to complementary DNA (cDNA).
In this test, a swab is taken from the throat or nose of the person who is getting tested. This swab contains a small quantity of the RNA of the virus, therefore it is amplified to produce material that is enough for testing whether or not coronavirus has infected the person.
To detect the same in the test, the RNA is converted into a two-strand DNA, using the process known as reverse transcription. Although this test is more accurate than a rapid antigen test, the time taken is also more. The test can be completed in four to eight hours, however, the results are available in one day due to time taken in collection and in the transportation of samples to the labs.
Running RT PCR machines is also expensive and that is why, labs run large batches of RT PCR tests together. This also adds to the time taken by labs to conduct this test. If the testing lab is far from the place where the sample of the person has been collected, the test result may be available after 48 hours or more, in some cases.
On the other hand, the results of the rapid antigen test can come out in about half an hour but the accuracy is less than that of an RT PCR test.
The cost of RT PCR test in private labs has recently been reduced by the Delhi government and is now capped at Rs 800, if the sample is collected at the facility. However, if a technician comes to your home for sample collection, the maximum price that can be taken for the same is Rs 1,200. In the state of Uttar Pradesh, the government has capped RT PCR testing at Rs 600.