Background

Ghana hailed the innovation by INCAS DIAGNOSTICS and the local production of a Rapid Diagnostic Test (RDT) Kit for SARS COV-2 infections (COVID-19) in Ghana.   What many did not know was the fact that the regulator (Food and Drugs Authority (FDA)) according to the Public Health ACT for medical devices needed to approve its use in Ghana for its intended purposes.

RDTs are constructed in such a way that they can identify antibodies to SARS COV-2 in an exposed person. The antibodies could be of three types; IgA, IgM and IgG. Depending on the antibodies determined, one could be said to have a past or current infection. These kits are used usually for the purposes of screening and anyone who turns out to be positive will need confirmation to be sure of the presence or absence of the virus.

The RDT by INCAS DIAGNOSTICS can determine antibodies (IgM and IgG) in the blood of infected people with COVID-19 in a maximum of 15 mins to tell if someone is or has been exposed. When patients recover, it will be a good tool to check if they have developed antibodies to protect them against future infections. What the RDT cannot do is to tell if the virus (antigen) is present in the blood sample of the infected person. It cannot be used as a substitute for the PCR method. However, it presents one of the cheapest ways to screen for exposure to the virus.

Diagnostic Performance

The performance of the RDT needs to be confirmed by what is called validation which captures the sensitivity, specificity, the predictive values, and the receiver operator characteristics of the area under the curve drawn by the sensitivity and specificity of the kits. Of great considerations are the sensitivity and specificity of the kits. Usually, the performance of the RDT is compared to another method that is accepted as the reference method (“gold standard”). Sensitivity is estimated as the number of samples the reference method identified as positive that the RDT correctively identified as positive. The number of samples that are negative and correctively confirmed as negative by the RDT gives the specificity of the kit. False-positives and false-negatives given by the RDT might affect the performance rating.

It is very important that the appropriate reference method is used to validate test kits. If the method is serological, then the best approach is to use a serological “gold standard” to validate the kit qualitatively. An antigen-based method must equally be validated with an antigen-based “gold standard”.

Considering the RDTs manufactured in Ghana and submitted for validation by the FDA, any attempt to use the molecular-based PCR technique as the gold standard to check if the kits will perform well might end up declaring the RDTs as non-performing.

Let’s break this further. The RDTs can only be validated with samples of known COVID-19 status (both positive and negative samples). Because blood (whole blood, serum, or plasma) is the most suitable matrix for the RDT, no other samples from the patients could be used for validating the test kit. The RDT basically determines the presence or absence of antibodies (IgM and IgG) and for that matter, samples of known antibody concentrations established with the “gold standard” must be used.

In preparing to validate a test kit or method, one other important factor to consider is how many of the positive and negative samples each need to be used. If the focus is on using the RDT as a screening tool, then one can compromise the specificity to gain more sensitivity since all positive samples would be referred for confirmation with an accepted method (in this case PCR).

Benefits of the COVID-19 RDT by INCAS DIAGNOSTICS?

RDTs are mostly used as screening tools for their intended infectious diseases. At the moment, RDTs are not recommended tools for diagnosing COVID-19 patients but they have their place in serological surveillance. Many guidelines are using the taking of temperatures of people to be able to screen people exposed to the virus. This is coupled with further screening questions to be able to zero in on possible exposed people. In place of all these, the RDT with just a drop of blood from an individual within 15 mins could inform if an individual is exposed to SARS COV-2 or not. It can be very useful to screen workers of companies and at our borders before allowing entry into the country. With the increasing infections among health workers, efforts could be made to use these RDTs to screen workers periodically.

Are other countries using COVID-19 RDTs? 

COVID-19 RDTs in several forms are part of the many arsenals used by most countries in the fight against the COVID-19 pandemic. Several of these kits have been given emergency use authorization in the USA to augment the screening and testing processes. One of such developed by LifeAssay in South Africa has been registered for use in the USA, UK, Germany, and the Philipines. Spain in the early days of the pandemic is known to have employed the use of RDTs as part of the public health tools in fighting COVID-19.

in the Africa Region, Senegal has deployed the use of RDTs for mass screening of the population. Ghana could join the league of nations to deploy some of these tools for screening on a mass scale.

Conclusion

It is good news to have such innovation by INCAS DIAGNOSTICS to produce COVID-19 RDTs in Ghana. It is the wish of many that this comes into force to help in the fight against the pandemic. The regulator is expected to work with the developer to make sure the product is used. At a time where reagents for PCR testing are increasingly becoming expensive and scarce, RDTs are some of the cheap tools that should be employed in order not to deny some people testing.

Ghana is blessed with innovation and we should ensure to appropriately validate the kit to give it its rightful indication and place in the fight against COVID-19.