A quick update on the TESTS for COVID-19 – By InfoMed – 02 June 2020
We need evidence-based protocols for Employers who can use to bring back employees to the workplace safely.
This is a short guide and pertinent information based on science and evidence up till now to help offices and workplaces to bring employees back.
The focus here is on the testing protocols as there is a sudden proliferation in the supply of test-kits in the market that the employers can find it challenging and overwhelming in deciding the right test-kit to be used cost-effectively.
There are two broad categories of test: a viral test for a current infection, or an antibody test for the past presence of the virus.
Reverse transcription polymerase chain reaction (RT-PCR) is a technique that first uses reverse transcription to convert the extracted RNA into DNA and then uses PCR to amplify a piece of the resulting DNA, creating enough to be examined to determine if it matches the genetic code of SARS-CoV-2.
When testing an infected person, the likelihood of detecting the virus depends on how much time has passed since the person was infected. According to Christian Drosten, the RT-PCR test performed with throat swabs is reliable only in the first week of the disease. Later on, the virus can disappear in the throat while it continues to multiply in the lungs. Christian is the head of the German public health institute’s reference lab on coronaviruses and was one of those who identified the Sars virus in 2003.
Essential Updates in Malaysia for Testing
- Test results – typically, the RT-PCR test results take about 24 hours. However, due to the high volume, it may take longer, anywhere from 2 days to a week. Thus, after many days when the test results are received, it may not reflect the current health status of the person tested.
- MMA cautions the public that Covid-19 tests are merely precautionary measures and not a guarantee against Covid-19 infection. You can still be infected after testing negative if you do not follow the guidelines on prevention.
- 11 May 2020: The Ministry of Health, Malaysia said it does not recommend the usage of the antibody rapid test kits (RTK) for the screening of Covid-19, as a negative test result does not guarantee the individual is free of the virus. The tests that are recommended for screening purposes are the antigen RTK test and the reverse-transcription polymerase chain reaction (RT PCR) test.
The different tests for COVID-19
|No||Test||The Science||Testing Method|
|1||RT PCR (reverse-transcription polymerase chain reaction)||Detects the presence of the virus (the genetic material of the virus) at the time of testing. If it is negative, you probably were not infected at the time your sample was taken. This molecular test is considered very accurate. Result typically takes about 24 hours quality of the test depends on the swab used (should be nylon or foam, cotton contains its own DNA thus don’t work), the trained person taking the swabs, the quality of the specimen taken, and the laboratory condition. The sample taken goes into a tube and is sent to a molecular test lab. At the lab, the virus’s RNA, the molecule that helps regulate genes is extracted. Is then analyzed thru a process called polymerase chain reaction (PCR), which can detect whether the sample is positive or negative for COVID. This process at the lab takes about 6 hours to complete. The process is done in batches at the lab and a few cycles per day.||Nasopharyngeal swab by a trained person|
|2||Antigen RTK Test||The test detects specific proteins that are part of the virus. The results are produced in minutes. It is less expensive and more practical for large numbers of people. The positive antigen test result is considered very accurate. But there is also an increasing chance of false-negative results (an infected person shows negative antigen test result). Thus, antigen tests aren’t as sensitive as the RT PCR test.||Nasopharyngeal swab by a trained person|
|3||Antibody RTK Test (also known as serology testing)||The antibodies may not show up for weeks. It does not tell you if you have a current infection. There are a lot of unknowns about how exactly the body’s production of antibodies will translate to immunity to the disease, or for how long. Antibody testing is not currently effective to manage the individual patient as the testing quality varies, and results are unreliable. Even if you have some immunity, World Health Organization cautions that there is a lack of evidence on whether having antibodies means you’re protected against reinfection with COVID-19.||Blood sample (finger prick or drawing blood from the vein)|
The current state of antibody testing for COVID-19 is “a disaster,” said Roche CEO Severin Schwan, as a large number of potentially inaccurate tests enter the market fueled by sky-high demand.
This guideline shall be reviewed and updated as the science and findings on the coronavirus evolves with changes of the pandemic.
A contribution to evidence-based healthcare.