Review of COVID-19 testing and diagnostic methods

Abstract

More than six billion tests for COVID-19 has been already performed in the world. The testing for SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2) virus and corresponding human antibodies is essential not only for diagnostics and treatment of the infection by medical institutions, but also as a pre-requisite for major semi-normal economic and social activities such as international flights, off line work and study in offices, access to malls, sport and social events. Accuracy, sensitivity, specificity, time to results and cost per test are essential parameters of those tests and even minimal improvement in any of them may have noticeable impact on life in the many countries of the world. We described, analyzed and compared methods of COVID-19 detection, while representing their parameters in 22 tables. Also, we compared test performance of some FDA approved test kits with clinical performance of some non-FDA approved methods just described in scientific literature. RT-PCR still remains a golden standard in detection of the virus, but a pressing need for alternative less expensive, more rapid, point of care methods is evident. Those methods that may eventually get developed to satisfy this need are explained, discussed, quantitatively compared. The review has a bioanalytical chemistry prospective, but it may be interesting for a broader circle of readers who are interested in understanding and improvement of COVID-19 testing, helping eventually to leave COVID-19 pandemic in the past.

Keywords: Antibody to SARS-CoV-2; CLIA; COVID-19 tests; CRISPR; CT scanning; ELISA; False negative results; False positive results; LAMP; Lateral flow immunoassays; RT-PCR of SARS CoV-2; Rapid detection; SARS CoV-2; Time to results; Ultrasound scanning.

Graphical abstract

Fig. 1

Illustrated qPCR process from sample collection to result readout (Created in canva.com//Google Spreadsheet//"File:Baby Blue - a prototype polymerase chain reaction (PCR), c 1986. (9663810586).jpg" by Science Museum London/Science and Society Picture Library is licensed under CC BY-SA 2.0s). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 2

The illustration of the CRISPR-based amplification assay process for the detection of SARS-COV-2 (created in BioRender.com).

Fig. 3

Schematic Illustration of the detection of SARS-COV-2 by Amplification methods as RT-LAMP, RT-RPA, and RT-RAA (Reverse Transcription Recombinase-Aided Amplification) (Created with BioRender.com).

Fig. 4

Detection of viral antigen and particles in nasopharyngeal swabs. Top – fluorescence-based sensor; bottom – mass spectrometry method. (created with MS Publisher).

Fig. 5

SARS-CoV-2 viral particles bind to gold nanoparticles functionalized with antibodies targeting three SARS-CoV-2 surface proteins (spike, envelope, and membrane), and color of the solution changes. The binding of the viral antigen to functionalized nanoparticles red-shifts extinction spectrum of the solution. The extent of such shift depends on viral load. Reproduced under Creative Commons License from an open access article by Ventura et al. [147]. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 6

Reagent-free chronoamperometry sensor. Binding of virions or spike protein to the spike-specific antibody anchored to the electrode through DNA aptamer causes changes in current, which are detected by chronoamperometry. Reproduced with permission granted by American Chemical Society from the article by Yousefi et al. [150].

Fig. 7

Schemes of serological assays ELISA, CLIA, and LFIA for detection of SARS-CoV-2 antibodies. CIA is KPS-QQ80 Chemiluminescence Immunoassay Analyzer is from instrumentstrade.com; MR is NS-100 Nano Scan Microplate Reader from hercuvan.com. The figure is created with miro.com.

Fig. 8

SARS-CoV-2 Detection Process by X-ray and CT scan. Positive and Negative X-ray and CT scans are retrieved with permission from an open-access article by Saha et al. (2021) [226]. Lung ultrasound images are retrieved with permission from an open-access article by Smith et al. (2020) [227]. X-ray machine icon is obtained from Alibaba (2021) [228]. Lung ultrasound machine icon is obtained from Flaticon (2021) [229]. CT scan machine icon from CleanPNG (2021), and Computer icon from PinClipart (2021). Note: Figure was made with miro.com.