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PCR or polymerase chain reaction is a laboratory test to detect the presence of genetic material from cells, bacteria, or viruses. Currently, PCR is also used to determine whether a person is infected with COVID-19 disease or not
Genetic material in every living cell, including bacteria or viruses, can be DNA (deoxyribonucleic acid) or RNA (ribonucleic acid). These two types of genetic material are distinguished by the number of chains they contain.
DNA is genetic material with double chains, while RNA is genetic material with single chains. The DNA and RNA of each living species carry unique genetic information.
The presence of DNA and RNA will be detected by PCR through amplification or propagation techniques. Well, with PCR, the presence of genetic material from several types of diseases caused by bacterial or viral infections will be detected and ultimately can help diagnose these diseases.
Some of the diseases that can be diagnosed through PCR tests are:
- Human immunodeficiency virus (HIV)
- Hepatitis C
- Human papillomavirus (HPV)
- Lyme Disease
- Pertussis (whooping cough)
In addition to diagnosing a number of diseases above, PCR tests are also used to detect the Corona virus that causes COVID-19. Corona virus is a type of RNA virus.
PCR Test to Diagnose COVID-19
The examination procedure begins with taking a sample of phlegm, mucus, or fluid from the throat (nasopharynx), nose (oropharynx), or lungs of patients suspected of being infected with the Corona virus.
Sputum sampling is done by wiping (swab) the nose and throat for about 15 seconds. You may feel a little uncomfortable during and after the procedure. Next, the sputum sample will be examined in the laboratory.
Well, because the Corona virus that causes COVID-19 is an RNA virus, the detection of this virus begins by converting the RNA found in the sample into DNA. The process of converting viral RNA into DNA is carried out by the reverse-transcriptase enzyme.
The technique of examining RNA viruses by first converting them into DNA and detecting them by PCR is called reverse-transcriptase polymerase chain reaction (RT-PCR).
After the RNA is converted into DNA, then the PCR tool will amplify or multiply this genetic material, also known as the CT value, so that it can be detected. If the PCR machine detects Corona virus RNA in the sputum or mucus sample being examined, the result is said to be positive.
PCR Test to Confirm Rapid Test Results
In addition to diagnosing infection with the SARS-CoV-2 virus, the PCR test can also be used to confirm the results of the rapid serological test. This is because the rapid test is not a test to diagnose COVID-19, but only as an initial examination or screening to detect the presence of IgM and IgG antibodies that are produced by the body when exposed to the Corona virus.
Please note, the formation of IgM and IgG antibodies takes 2-4 weeks after the virus enters the body. Therefore, a negative result on a rapid test cannot be used as a determinant of a person not being infected with COVID-19.
A positive result on a rapid test also cannot be used as a determinant that someone is infected with COVID-19 disease. This is because the antibodies detected can be IgM and IgG which are formed by the body due to other viral infections, including viruses from the coronavirus group other than SARS-CoV-2. Results like this are said to be false positives.
This is where it is important to do a PCR test. Because until now, the PCR test is a diagnostic test that is considered the most accurate to determine whether a person has COVID-19 or not.
If you still have questions regarding the Corona virus and its examination, ask the doctor directly through the ALODOKTER application. In this application, you can chat directly with a doctor or make an appointment with a doctor at a hospital if you need an in-person examination.