With the increasing cases of Coronavirus Disease 2019 (COVID-19) in Malaysia, tests for COVID-19 are commonly available in public or private health settings. You can easily search with the keyword ‘covid test near me’ to look for the available places offering the tests. The two common tests that are currently available are the reverse transcription polymerase chain reaction (RT-PCR) and antigen rapid test kit (RTK-Ag), in which both would require a nasal swab sample. In this article, we will look into detail on how to read a COVID test report, particularly the Cycle threshold (Ct) value mentioned in the report.
Nasal Swab Test
A nasal swab test is an easy, fast and effective way of determining a person with an active COVID-19 infection.
In this procedure, you will be required to take a seat and tilt your head back. The health professional will then insert a 6-inch cotton-tipped swab into the area between your nose and your throat, known as the nasopharynx. The brush is twirled for a few circles up to 15 seconds to get enough samples of nasal discharge. After that, the health professional will remove the brush and insert it into a specimen tube. You might feel some discomfort during the procedure and it might trigger some normal reflexes of your body such as the gag reflex and lacrimal reflex (stimulation to produce flow of tears).
While waiting for the result to be released, it is recommended for you to self-quarantine at home.
Interpretation Of Test Result
Reverse transcription polymerase chain reaction (RT-PCR)
RT-PCR is a widely used laboratory test to test for the presence of COVID-19 virus from the nasal sample. In this test, the genetic material of the virus is amplified to improve the detection of the virus. It is also a diagnostic test for COVID-19.
A positive test indicates the person has an active infection of COVID-19. Your screening centre will then register you as a positive COVID-19 patient and inform the district health department within 24 hours. You will then be referred to the COVID-19 assessment centre for further assessment and appointment.
A negative result indicates that the person does not have an active COVID-19 infection.
Ct value refers to the number of cycles required to amplify virus level to be detectable in laboratory tests. A lower number of cycles implies a higher virus load which is easily detectable. A person is considered COVID-19 positive if the Ct value is lower than 35-40.
The Ct value also implies the infectivity of the disease but does not correlate with the severity of the disease.
Antigen Rapid Test Kit (Rtk-Ag)
RTK-Ag is a relatively inexpensive and fast screening test which can produce results in less than 30 minutes. It is effective in detecting a coronavirus outbreak quickly.
It works by detecting a specific protein on coronavirus causing COVID-19.
A positive result indicates the person might be infected with COVID-19. It is recommended for this group of patients to proceed with the RT-PCR test within 24 hours as a confirmatory test depending on their clinical history.
A positive result will be reported to the district health department within 24 hours.
RTK-Ag might lead to a false negative result. Depending on the clinical judgement of the clinician, a person with a negative result might require a further RT-PCR test within 48 hours to be excluded as confirmed COVID-19 patients.
Nasal swab test is a common method to collect samples for RT-PCR and RTK-Ag in Malaysia. RT-PCR is known as the diagnostic test for active COVID-19 infection while RTK-Ag acts as an effective screening tool. If you experienced any symptoms suggesting COVID-19, kindly visit your doctor immediately.