The nature of the Coronavirus disease is such that one can test negative now and contract the virus the next minute if care is not taken. That’s why many people get tested everyday. But unfortunately, the results don’t always get it right as an August 18, 2020, publication by Bestlife.com revealed.
The spiraling rate of the virus has left many worried as the search for vaccine hasn’t completely materialised.
According to the report, U.S. Food and Drug Administration (FDA) says Thermo Fisher’s TaqPath is one of the test kits that was returning false findings.
The FDA issued a public statement on August 17, notifying laboratories and healthcare providers that there was a “risk of false results” associated with the Thermo Fisher Scientific TaqPath COVID-19 Combo Kit, a swab test conducted either on your throat or nose that can produce results in just a few hours.
This left much to be desired of how tests were carried out in detecting cases. The interesting thing is, if a country like the United States is having these shortfalls in testing for the virus, then the fate of developing countries like Ghana needs to be assessed as far as testing for the Coronavirus is concerned.
The Director of the Noguchi Memorial Institute for Medical Research, Professor Abraham Kwabena Anang has explained to Fact-check Ghana, the forms of testing that exist, the challenges associated with them, and the one commonly used in Ghana and its rate of efficiency.
There are three main types of testing according to him.
Molecular test
This type of testing is also known as the PCR. Prof. Anang says the ability of a particular test kit to detect the virus under this type differs in terms of how small amount of the virus is present. So even though you can get PCR tests that can detect COVID-19 alright, people with a certain low concentration of the virus would not be found to be positive due to the variance in sensitivity. Sensitivity is the ability of the test to detect positive.
Detection of antibody: Also known as the Rapid Diagnostic Test (RDT), this is the other form of testing for a virus. Prof. Anang indicated that when a virus enters the body, the RDT uses cross reactivity of the kit to detect antibody in the system since the immune system recognises and produce antibodies against the virus.
The effectiveness of this, he says, “depends on how well the scientist who developed the test kit checked for cross reactivity. Cross reactivity means that for any virus or pathogen that enters the body, an antibody is produced. But you must find the antibodies that are produced against Covid-19, which are different from the ones produced against other pathogens in the body. So if the cross reactivity is not well checked, you may say one has tested positive for Covid-19, but it is for the other viruses that are inside the body.”
“That notwithstanding, if it is well produced, it also gives a problem because if you remove all the other antibodies because you are introducing Covid into a system, you may get a result such that, some people with Covid, will not show antibody,” he said.
The last but not the least is the Detection of antigens. He explained that, “when a virus enters a body, it reproduces itself, part of it die, part remains. So any part of the virus that remains in the system is antigen and they are usually detected using antibodies. So you select an antibody, use it to detect the virus particles that is the antigens.”
Noguchi, he said, has however been collaborating with the Food and Drugs Authority (FDA) to ensure all dysfunctional and problematic kits are disapproved.
The only challenge he said was with the RDTR. He said sometimes when people are strained, it is not able to detect those with very low amount of the virus. So after evaluation, they advise the FDA not to recommend such kits.
Prof. Anang noted there are bigger challenges with the antibody detection kits because of the way the Coronavirus interacts with the immune system. He said some of them are not sensitive at all.
“For some of them, if we give them known positive cases of say, 100, the maximum they can detect is sixty something, which means the remaining would be said to be negative. Meanwhile they are positive,” he said.
The good news with Ghana’s testing system, he disclosed, was that Ghana was not “using too many different kinds of tests, so we don’t have that problem. In Ghana, the major test we are using is the RTPCR and it is the most sensitive and the most globally recommended.”
Supported by STAR Ghana Foundation with funding from UKAID and the European Union
