Antigen swabs have recently been widely discussed after the Head of Petamburan Urban Village, Central Jakarta, was declared reactive COVID-19 through this test. Later, he was confirmed positive by means of a PCR swab.
Actually, what is an antigen swab and how is it different from a PCR swab or a rapid test?
dr Thyrza Laudamy Darmadi SpPK, clinical pathology specialist from Pondok Indah Hospital (RSPI) Bintaro Jaya explained swab antigen different from the rapid test. It was said that the rapid test generally detects COVID-19 antibodies in the body, while the antigen swab detects viral proteins.
The difference between antigen swabs and PCR swabs
The method for taking the COVID-19 antigen swab test in taking samples is similar to RT PCR (Real Time Polymerase Chain Reaction), which is taking samples in the nose and throat. However, the antigen swab is only able to detect the virus when the viral load is high.
“So the antigen is able to detect when the patient’s virus count is high, but when the virus count is not too high, so the CT (cycle threshold) value is above 25 or above 30, the antigen could be negative,” explained Dr. Thyrza when met. detikcom at RSPI Bintaro Jaya Friday (20/11/2020).
“In fact, the patient contains the virus, contains the COVID-19 virus, so it is less sensitive to detect than PCR,” he continued.
Another difference, RT-PCR requires a special laboratory with bio safety level (BSL) qualifications 2.
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dr Thyrza Laudamy Darmadi, SpPK Photo: detikFOTO— |
The difference between antigen swab and rapid test
Although the results are both stated as reactive and non-reactive, the process of reading the results of the two COVID-19 tests, both the antigen swab and the rapid test, takes different times.
Rapid test results come out within 15 minutes, while new antigen swabs can show results at least 30 minutes after being tested.
The sample used is different, the antigen swab takes samples from the nose and throat the same as the RT PCR, while the rapid test draws the patient’s blood.
Your COVID-19 antigen swabs are best checked during the first week after symptoms develop. While the rapid test is better used during the second week after symptoms or more than 7 days.
“The comparison between the accuracy of the rapid antigen and the rapid antibody cannot be compared because the time frame for use is different between the rapid antigen and the rapid antibody. In the first week, the rapid antigen test is more sensitive and accurate than the antibody to show someone has COVID-19 or not,” he concluded.
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