August 18, 2021 | Written By: Sofia Farudz
COVID-19 infection is raging in our country as well as around the world. The increasing cases of infection and emergent of new variants that are getting stronger are of great concern to everyone. More screening tests are being conducted in the red zone area to curb the spread of this infection. In addition, some travelling pass applications or admission to certain organizations also require screening test results.
Of course many are surprised to find that there are many types of screening tests and confirmation tests for COVID-19 infection. Which one is most accurate, and do the tests differ according to the situation or need? Follow this article to know the types of COVID-19 tests and how each of them works.
Different Types of COVID-19 Tests
1. RT-PCR Test
The RT-PCR test has been shown to has the highest accuracy. This test is most sensitive for detecting active COVID-19 infection and is the gold standard in the diagnosis of COVID-19 infection.
As the name suggests, this test uses the reverse transcriptase technique to detect the presence of COVID-19 virus genetic material from swab samples taken from the nasopharyngeal tract i.e. nose or throat.
The material from the sample was mixed with certain chemicals to separate other substances such as proteins and fats to obtain pure RNA. This RNA is then processed using the reverse transcriptase technique to obtain DNA with the help of an enzyme.
After that, certain parts of the viral DNA are added to the resulting DNA. If there is a virus in the sample, this part of the DNA will be attached to the DNA of the virus. The mixture will then be put into an RT-PCR machine that will duplicate the resulting DNA to detect its level. The machine also provides a CT value that tells how many cycles it takes to detect the virus. The fewer cycles or the lower the CT values usually indicate a more serious infection.
RT-PCR test results usually take longer to obtain. Although one test typically takes approximately 2 hours, it may take a longer time for facilities with many samples to get the results.
2. RTK-Ag test
The RTK-Ag test is also known as the rapid test or Rapid Test Kit Antigen. Compared to the RT-PCR test, the results for this test can be obtained within 15-30 minutes.
The RTK-Ag test has a lower accuracy rate than the RT-PCR. However, it is very useful for mass COVID-19 screening to detect active infections.
Unlike RT-PCR which uses genetic material from the virus to detect infection. The RTK-Ag test detects a type of protein that is on the surface of the virus. The test also requires a swab sample from the throat i.e. the nose or throat.
3. Antibody Test
Another test that is also used to detect COVID-19 infection is the antibody test. This means that this test detects antibodies that have built up after being infected for a while.
Therefore, this test done by using blood droplets can only detect someone infected after some time or those who have recovered from the infection.
Those with active infections may not be detected with this test because individuals who have been infected but are still in the incubation period will show negative results. So it is not suitable to be used as a screening test
4. Saliva Test
This test has just been introduced recently as a screening test worldwide including in Malaysia. It has also been approved by the FDA.
There are two types of saliva tests, one that is taken as samples and then tested in the laboratory and also saliva self-test kits that can be done by any individuals themselves.
The saliva self-test is also a type of RTK-Ag test that detects the presence of proteins or antigens on the surface of the virus in a sample. Compared to the regular RTK-Ag Test which requires a nose or throat swab, this test only requires someone to spit their saliva. It is non -invasive and easier to use. In addition, the approval of this test from the FDA also reduces the exposure of medical professionals to infection and lessen their burden because it can be done by the general public themselves.
The following is a list of saliva self-test kits that have been approved by the Medical Device Association Malaysia for sale to the public.
BRIGHT-COVID-19 Antigen Rapid Test Device
JustCheck COVID-19 Antigen Rapid Test
Source: Ministry of Health Malaysia
Users who wish to use this COVID-19 self-test kit must obtain it from a registered pharmacy. Make sure you use the test kit correctly and are responsible for reporting the actual test results.
It should be noted that this COVID-19 saliva self-test kit is only a screening test. Those who get a test result that is found to be positive should report the test result and inform the nearest health facility for further action. Those who use this test must upload their test results regardless of positive or negative to their respective MySejahtera applications.
*The free doctor consult initiative is supported and fully funded by DoctorOnCall