Comparative analysis of point-of-care diagnostic techniques for respiratory infectious diseases. Lessons we learned from the COVID-19 pandemic and future consideration on more competent alternatives

Our unpreparedness in responding to the prompt emergence of COVID-19 in its early stage of outbreak, especially the lack of rapid and early diagnostic techniques for mass screening which should have been prioritized, contributed to the virus' spread alongside other factors. This article provides an overview of the common diagnostic techniques with special focus on the reported and/or authorized point-of-care methods for early COVID-19 diagnosis, including lateral flow assays and localized surface plasmon resonance-based approaches. The inherent limitations of these techniques are critically examined. We then propose a potentially more competent alternative, i.e. direct detection of viral particles with aptamer-conjugated gold nanoparticles in liquid solution in combination with noninvasive breath sampling or saliva sampling, for further improvement in early diagnostic capability for infectious respiratory diseases like COVID-19. In addition, an integration of air sampling with in-situ direct colorimetric detection of viral particles could represent a potential option for airborne virus detection, thus minimizing the transmission of infectious diseases and their impact on the economy and life in the future.