COVID-19 testing equipment needs a relook

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REPORTS that three nurses in Mashonaland East province tested positive and then negative on review raise a question that health authorities need to answer to restore confidence in their response to the coronavirus outbreak.

NewsDay Comment

Zimbabwe is using the rapid diagnostic tests (RDT), which only gives a result if they detect anti-bodies in the body, and not that they have detected the coronavirus itself. This is causing some trouble.

National University of Science and Technology head of the Applied Genetics Testing Centre, Zephaniah Dlamini, told Finance minister Mthuli Ncube during a tour of Mpilo Central Hospital in Bulawayo at the weekend that faulty test kits were causing confusion in the collation of coronavirus statistics.

He said they relied on polymerase chain reaction (PCR) test machines.
Mashonaland East provincial medical director Simukai Zizhou also said the RDT tests were not specific and that they could only pick anti-bodies after a period of 14 to 21 days after infection. Other governments have withdrawn thousands of coronavirus test kits because they did not produce accurate results.

It is easy to see why the government is using the RDT because they typically produce results within 30 minutes.

The World Health Organisation cautions that “how well the tests work depends on several factors, including the time from onset of illness, the concentration of the virus in the specimen, the quality of the specimen collected from a person and how it is processed, and the precise formulation of the reagents in the test kits. Based on experience with antigen-based RDTs for other respiratory diseases such as influenza, in which affected patients have comparable concentrations of influenza virus in respiratory samples as seen in COVID-19, the sensitivity of these tests might be expected to vary from 34% to 80%.”

It also notes that “half or more of COVID-19-infected patients might be missed by such tests, depending on the group of patients tested. These assumptions urgently require further study to understand whether they are accurate. Additionally, false-positive results — that is, a test showing that a person is infected when they are not — could occur if the anti-bodies on the test strip also recognise antigens of viruses other than COVID-19, such as from human coronaviruses that cause the common cold. If any of the antigen detection tests that are under development or commercialised demonstrate adequate performance, they could potentially be used as triage tests to rapidly identify patients who are very likely to have COVID-19, reducing or eliminating the need for expensive molecular confirmatory testing.”

As a result, WHO does not recommend the use of RDT.

Should Zimbabwe keep using these gadgets? We are already testing way below the average of our neighbours because of lack of resources, general incompetence and corruption, but when we test, we need to get it right, so that we can as well concentrate on the testing that gives us accurate, reliable results.

We run the risk of rushing tests using dysfunctional equipment to paint a false picture of the COVID-19 situation in the country and it gets to haunt us again tomorrow.

Government has targeted to test at least 40 000 people within the month, but that accurate COVID-19 picture cannot emerge from using faulty testing equipment.