Summary and Perspective
Specificity and sensitivity are two fundamental requirements for an effective diagnosis. It is also important that the testing method is user friendly. RNA detection is the most frequently used method for the identification of COVID-19 patients because this method is extremely sensitive due to the power of nucleic acid amplification and also highly specific by using complementary nucleic acid probe/primer for the identification of a particular RNA. The major drawback in such an emergency situation is probably the requirement of well-trained personnel and lengthy testing time (usually 3-4 hours) to run the test. However, NAAT has been announced that positive/negative COVID-19 can be determined in about 10 minutes by using the isothermal amplification method. This may due to the simplification of the NAAT procedure and the high amount of the SARS-CoV-2 at the beginning of the infection be detected.
Detection on viral proteins, such as S and N protein, give complementary information to that of RNA detection from the same sample. This method is more direct (without amplification), but is less sensitive. It needs more effort to obtain a suitable probe (usually antibody), but the testing method can be simple. Recent developments in biosensing technologies can significantly improve the protein sensing sensitivity such as the use of magnetic bead to concentrate the protein molecules or by applying nanowire field-effect transistor as a transducer. Many of the entrepreneurs may take this opportunity to fasten their product development. Serology testing targeting on viral-induced antibodies is given different information as those for viral RNA and proteins from SARS-CoV-2. Although the protein testing method is similar, the targets are not part of the virus and the testing specimens used can be quite different as compared to those for viral protein detection.
It is unfortunate that the world is currently suffering from the COVID-19 epidemic. However, we can expect that such an incident will re-appear. We wish that the world will be better prepared every time when we face the potential spread of an infectious disease. Biosensing technologies have progressed rapidly in the past decade. The pandemic outbreaks of COVID-19 continue to remind us that diagnostic tools are critical and needed to be prepared in advance.