With the COVID-19 pandemic causing global devastation and leaving no stone unturned, testing for the virulent disease has become one of the most in-demand healthcare services all over the world. These test kits, from being only used sporadically in laboratories and hospitals, have become popularised and are now being disseminated widely and used in thousands by healthcare professionals and medical workers worldwide.

Singapore itself has ramped up its testing numbers to 50,000 a day as of the end of May. Moreover, while previously, those being tested were primarily migrant workers living in dormitories, our nation has now expanded testing to workers and residents in aged homes as well as pre-school teachers.

It is only logical that Singapore extends testing to other crucial aspects of the community, moving forward, as when the circuit breaker is eased, there will no doubt be a second wave of cases.

So what are COVID-19 tests exactly? You may have heard that these tests are being deployed in masses but what sort of tests are being used, how do they work and what exactly do they test for?

Polymerase Chain Reaction (PCR) Test

Polymerase Chain Reaction or PCR tests are currently the most widely used form of COVID-19 testing both in Singapore and across the globe. This form of testing was the first one to be formulated to detect the presence of the COVID-19 virus in an individual.

PCR testing is done by obtaining nasal, pharyngeal or sputum swabs from suspected patients. In PCR tests, viral RNA from samples is extracted and then converted into DNA through reverse transcription. This is done so that viral genetic material is amplified and made easier to pick out.

If viral genetic material is present in a particular patient’s sample, it is rendered fluorescent because of a specific dye that reacts in the presence of DNA. The more the viral genetic material, the more the fluorescence and thus, a pattern of fluorescence identifies the presence of the COVID-19 virus.

Samples for PCR tests are very easy to obtain since they require healthcare professionals or technicians to merely swab a patient’s throat or nose. However, the process of testing requires a high amount of labour in order for results to be out in the 1 or 2 hours that they are stipulated to be out in.

Moreover, samples also need to be transported to laboratories from the clinics or locations that they are obtained, and chances of contamination are increased when transportation of samples occurs.

The process is also error-prone, which can lead to a patient with COVID-19 being tested negative for the virus. Of course, the process of testing is constantly being refined to reduce errors, but the margin for errors is still higher when compared to other methods of testing.

Antigen test

Rapid Antigen Test

Bosch, a German engineering and technology firm, was the first to develop a method for rapid antigen testing. This method of testing can done in-house, without samples from patients having to be transported to laboratories, like with PCR testing.

Bosch’s antigen testing is hailed as the first fully automated molecular diagnostic test that can detect the presence of COVID-19 in an individual. A Bosch Vivalytic analyser and Vivalytic test cartridges are required for the test to be conducted. These test cartridges contain components that allow it to identify if COVID-19 antigens are present in an individual’s test sample.

The patient’s sample is first put into the cartridge and the cartridge is then put into the Vivalytic analyser, after which the test runs on its own. Results are obtained in about 2 and a half hours.

The good thing about Bosch’s rapid testing is that it requires minimal labour due to the automated process and it can also be done in-house as long as the clinic has the analyser and the test cartridges. This saves the time that is required for patient samples to be transported to labs and also reduces chances of contamination during transportation. Moreover, the test can simultaneously identify nine other respiratory infections in the patient such as influenza.

However, one Vivalytic test cartridge is required for each patient’s sample, which means that this mode of testing may prove to be high in cost. It is also a point of contention that not every clinic or healthcare institution around the world may have the means to obtain Bosch’s specific Vivalytic Analyser and cartridges.

Lateral Flow Assay

Testing via lateral flow assay is also a method of antigen testing, but one that does not require a swab to be obtained, a wait for the results and then a medical professional to analyse the results. It cuts short the process of testing by providing patients with a negative or positive result on a test strip. Sona Nanotech, a Canadian nanotechnology company, is currently working on churning out the first such lateral flow assay for COVID-19 testing.

The lateral flow assay for COVID-19 is flexible in that an individual’s blood, sweat, urine or other applicable bodily fluids can be used for testing. Sona Nanotech is developing the test such that specific nanorods bind to biological materials (antigens specifically) and then carry them along test strips, thus producing positive or negative results. Lateral flow assays such as these identify the presence of specific biological markers – in this case, it is the COVID-19 antigen.

Since this method tests directly for the COVID-19 virus, there are less chances for false positives or negatives to be obtained. Moreover, Sona expects test results to be out between 5 to 15 minutes, which would make the test the quickest COVID-19 test in the market if it and when it is ready. The cost of each test strip would also be less then USD50, which would optimise it for usage in all countries and across various demographics. The final benefit is that the test can be administered by untrained persons and does not require the supervision of a health professional.

Antibody Test

COVID-19 immunity passports have been hailed as the way through which life after the COVID-19 outbreak can go back to some sense of normalcy. These immunity passports, of course, refer to tests that detect COVID-19 neutralising antibodies in those who have previously been infected with COVID-19. These antibody tests cannot identify active infections, but can reveal who has some sort of immunity built up from previous infection with COVID-19.

The first test of its kind in Singapore, the cPass serology test, an antibody test developed by Singapore’s Duke-NUS Medical School and launched on May 15, detects antibodies in the blood or serum of patients who were previously infected with COVID-19.

Results for this cPass serology test can be reviewed in just an hour, making the test one of the quickest antibody tests. This antibody test also does not require live virus and cell materials, which means that the test is far safer and easier to mass-produce than other such antibody tests.

Instead of using live biological material, the test uses protein engineering to replicate a portion of the virus and a portion of a live cell that bind together. With antibody testing, longevity of immunity, herd immunity and other concepts relating to COVID-19 can be measured.

Currently there are more than 50 COVID-19 diagnostics tests produced by various research institutions and bio-medical firms in Singapore that have been approved for provisional local use by the Health Sciences Authority (HSA). This is so that Singapore does not face a shortage of good-quality test kits in times where COVID-19 infection rates soar. Do visit your General Practitioner or medical practitioner for advice if you are unwell and wish to get tested for COVID-19.