Challenges and prospects in current diagnostic techniques available for corona virus disease-19 (covid-19)

Background: The current global pandemic (SARS Covid-19), was first detected in Wuhan, in December 2019. The increasing magnitude and significance of identifying the cases have accentuated the importance of diagnostic approaches to Covid-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Major challenges are being faced in various phases of laboratory diagnosis, from pre-analytical to post-analytical processes. Although the gold-standard method for testing is real-time reverse-transcription polymerase chain reaction (rRT-PCR), various limitations such as low sensitivity at early stages of infection, longer turn-around time (TAT) and influence of external factors have been reported in various studies. Choosing ideal targetsfor nuclei acid amplification tests (NAATs) are important to increase the sensitivity and specificity of the assays and lower the limit of detection.At present computed tomography (CT) of chest has been reported as a reliable diagnostic technique, even in rRT-PCR false-negative cases. Immunodiagnostic assays are being developed recently to overcome the short-comings in rRT-PCR method, to confirm the active cases, as well as determine the immune status of asymptomatic patients. Reverse-transcriptase loop-mediated isothermal amplification (RT-LAMP) based assays, have been suggested as rapid, cost-effective point-of-care tests (POCTs). Currently various diagnostic assays are under development based on isothermal amplification, CRISPR, nanotechnology, biosensors and AI (artificial intelligence), most with potential for POCTs. Aim: To identify and compare the relevance of various techniques and tests under development to detect Covid-19. Methods: Original articles, review articles, commentaries and short communications regarding the assays to detect Covid-19 were thoroughly examined to summarise the observations. Conclusion: Understanding the biological properties of the virus is crucial forthe development of new diagnostic approaches which can provide precise identification with high sensitivity, specificity, and short TAT, thus aiding in real-time patient management and controlling spread of infection.”