Screening for COVID-19 is crucial to contain the spread of the virus. The virus can be detected in a sample by both the Reverse Transcription Polymerase Chain Reaction (RT-PCR) test and the Rapid Antigen Test (RAT). However, there are some uncertainties about which test you should get and why. In this blog, we look at the pros and cons of these popular COVID-19 diagnostic tests.
RT-PCR test
Accurate and efficient, this test can detect a COVID-19 infection even before the person becomes infectious, allowing for early isolation and preventing transmission. Nasal and oral swabs are taken and then processed. The test detects the presence of the RNA of the virus. While the results are available within 24 hours, generally, it takes around two to three days. If the demand is high, the results can take longer.
The test has a nearly 100 per cent specificity rate (ability to identify those without the disease), and a sensitivity rate (ability to identify those with the disease) of about 67 per cent. Therefore, while there will not be any false positives, there is a 30 per cent chance of getting a false negative. Apart from technology issues, incorrect sampling is a causative factor. Another reason is that lately, the public sees this as a precautionary test and gets it done even in the absence of symptoms. As the virus incubation period is around five days on average, and people test positive only after the sixth day, premature testing can give negative results as the viral load is extremely low.
The test is expensive, needs highly professional staff for sample handling, and extended evaluation periods. However, the RT-PCR test is still considered the gold standard for testing.
RAT
This test has gained popularity as it is quick and cheap. Only nasopharyngeal swabs are collected by trained healthcare workers and the test can be done in a clinic, doctor's office or hospital. The results are reported quickly, sometimes within 15 minutes. This test, too, detects the presence of viral proteins in a sample from a person's respiratory tract. It reveals patients at the peak of the infection when the body has the highest concentration of these proteins.
RAT's main disadvantage is that it is not as accurate as the standard RT-PCR tests in identifying those infected, meaning there is a higher probability of getting a false negative. What makes this test sought after is the price, quick results and lower demands on the staff's expertise.
If you are getting a RAT, it would be best to back it up with an RT-PCR test to get a clear picture.
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