The diagnostic methods in the COVID-19 pandemic, today and in the future

Abstract

Introduction: The emergence of anovel coronavirus identified in patients with unknown cause of acute respiratory disease in Wuhan, China at the end of 2019 has caused aglobal outbreak. The causative coronavirus was later named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the disease caused by SARS-CoV-2 was named as Coronavirus Disease-2019 (COVID-19). As of 10 August 2020, more than 19,718,030 confirmed cases and 728,013 deaths have been reported. COVID-19 is spread via respiratory droplets which are inhaled into the lungs. Areas covered: In this article, we summarized the knowledge about the causative pathogen of COVID-19 and various diagnostic methods in this pandemic for better understanding of the limitations and the nuances of virus testing for COVID-19. Expert opinion: In this pandemic, rapid and accurate identification of COVID-19 patients are critical to break the chain of infection in the community. RT-PCR provides a rapid and reliable identification of SARS-CoV-2 infection. In the future, molecular diagnostics will still be the gold standard and nextgeneration sequencing can help us to understand more on the pathogenesis and detect novel mutations. It is believed that more sophisticated detection methods will be introduced to detect SARS-CoV-2 as earliest as possible.

Review of Current COVID-19 Diagnostics and Opportunities for Further Development

“…In a recent systematic review and meta-analysis, the mean duration of SARS-CoV-2 RNA shedding was 17.0 days (95% CI 15.5-18.6; 43 studies, 3,229 individuals) in the upper respiratory tract, 14.6 days (95% CI 9.3-20.0; seven studies, 260 individuals) in lower respiratory tract, and 17.2 days (95% CI 14.4-20.1; 13 studies, 586 individuals) in stool (103). An earlier study highlighted two COVID-19 cases with positive stool before pharyngeal specimens (102), suggesting that stool may be an alternative to respiratory specimens for early virus discovery in individuals unable to provide respiratory samples, such as infants (104). Stool as a source is consistent with the virus being found in wastewater, where it is presumed to survive several days.…”

“…Different institutions rely on varying numbers of SARS-CoV-2 gene targets and different target regions. Gene targets include structural proteins, which have higher sensitivity for coronavirus detection, and species-specific SARS-CoV-2 accessory genes (104). Use of multiple PCR targets helps to avoid falsenegatives associated with mutations in the primer site, especially mismatches at the 3' end (117,118).…”

A review on current diagnostic techniques for COVID-19

“…There are several current endeavors to develop less expensive, faster, and dependable diagnostic tools based on specific SARS-CoV-2 antigens detection to be used as rapid diagnostic tests [188]. This approach intended to directly reveal, in respiratory secretions, the highly expressed viral antigens during virus replication [188][189][190], has a suboptimal sensitivity and requires adequate concentration of antigens. Therefore, the antigen assays could potentially be employed as a triage test to quickly highlight the patients susceptible to have COVID-19 infection [189].…”

“…As with antibody testing, the principle of antigen detection relies on the mobilization of the sample along the test strip by capillary action [190]. These assays are not limited to a particular format as the target antigen can be captured by fluorescent-labeled or colloidal gold antibodies.…”

Detection of SARS-CoV-2- specific antibodies in asymptomatic healthcare workers in a tertiary care hospital in NCR

“…Though RTPCR has been the mainstay of covid diagnosis, the importance of serological diagnostic procedures cannot be underestimated. Combining RTPCR with serological assays increases the sensitivity of diagnosing Covid19 many fold [6] which can be helpful in setting various protocols. Whereas RTPCR detects the viral genome in patients sample and clearly tells about the presence or absence of disease, serological detection of IgG, IgM or IgA tells about past or present infection and immune status of patient against Covid.…”