Expert speaks about tests

Many Mossel Bay residents may wonder which tests are available to detect Covid-19. Chemical pathologist Dr Elza Coetzee says currently two types of tests are available. Coetzee says they make use of either tests that search for the virus currently, or tests that ascertain virus exposure.

"We diagnose Covid-19 by identifying actual specific viral genetic material (RNA) using the gold standard RT-PCR test (Reverse Transcriptase Polymerase Chain Reaction), sometimes called a nucleic acid test."

This test does not confuse one virus with other viruses. Thus, a positive result indicates the presence of SARS-CoV-2 viral material in the sample.

"The sample best representing the habitat of the virus is the epithelial cells in the nasopharynx (right at the back, where nose and throat connect), hence most laboratories and international visas prefer the more trustworthy, yet infamous deep nasal swab to the slightly less sensitive oral swab."

Coetzee says it is unfortunately an expensive, time-consuming, specialised molecular test and despite initial hurdles, South African laboratories did themselves proud by reaching and maintaining world-class turnaround times.

The antibody test is a blood test which determines whether the body has developed antibodies specifically toward this virus. "It is therefore a wonderful retrospective tool (only really helpful 14 days after being infected), and has limited use in active disease without proper result interpretation, and should only be done when recommended by a medical practitioner."

There is still, according to Coetzee, much uncertainty as to whether antibodies to this virus offer any immunity, as well as to the extent and duration of immunity. Careful interpretation is also imperative for commercially available “rapid tests” which similarly test for antibodies and have limited clinical value.

"A person’s behavior should not change based on their Covid antibody result. Kindly contact your medical practitioner or local laboratory for more information," says Coetzee.