Swabbing for Covid-19
TESTING for Covid-19 continues to be the primary form of defence in the fight to tackle, contain and prevent the spread of the SARS-CoV-2 virus that is ravaging the country and world.
Malaysia’s public healthcare system’s capacity to conduct testing for the virus has increased over the last couple of months.
However, these free tests are targeted at specific groups, like those who have contact with confirmed Covid-19 cases, e.g. in suspected clusters and enhanced movement control order (EMCO) areas, and Malaysians placed in quarantine after returning from overseas.
However, some people who are not in these groups might suspect that they have developed symptoms of Covid-19 and wish to test for the virus.
They can do so at certain private hospitals, which provide Covid-19 screening services on nasopharyngeal and oropharyngeal swabs, otherwise known as nasal and throat testing.
The swab test is usually done at a designated area next to the hospital’s Emergency Department in order to contain any possible positive Covid-19 cases to this area.
Drive-through testing is usually also available, where you can remain your car while getting swabbed.
Some hospitals are able to analyse all the samples in their own laboratory, enabling the results to be available more quickly.
Testing can help determine how the virus impacts different people based on age and health condition among other factors.
This will help determine treatment and course of action.
Wider spread testing will enable the healthcare sector to gain deeper understanding of this relatively unknown virus as quickly as possible.
A genetic test
The Covid-19 test is a molecular diagnostic test done in a controlled environment (in vitro) to detect the presence of the SARS-Cov-2 virus in a person’s swab sample, using the real-time RT-PCR (reverse transcription polymerase chain reaction) method.
The PCR test detects the virus directly, thus indicating whether an active infection of Covid-19 is present.
The test uses a set of DNA (deoxyribonucleic acid) fragments that complement three target RNA (ribonucleic acid) genes of the virus.
If any of the SARS-CoV-2 viral RNA is present, these DNA fragments will bind to it.
Chemical markers in the form of fluorescent dye or reporter molecules attached to the DNA fragments will release fluorescence during this DNA binding, which is visible on the result strip.
The entire process of analysing one swab test can take up to a day and involves the following three key steps:
> Sample deactivation
The sample will undergo heat inactivation at 65°C for one hour to kill the virus.
This is to ensure that it is no longer infectious and safe to handle in a laboratory.
Lab personnel handling the sample deactivation must wear full personal protective equipment (PPE), including a disposable isolation gown, double gloves, an N95 face mask, a face shield, a hair cap and shoe covers.
> RNA isolation
This step is carried out in a fully automated and closed system to isolate the RNA from the virus cells.
> PCR amplification and data analysis
The isolated RNA is amplified (duplicated many times) and analysed by a real time RT-PCR machine.