Current Status of Diagnostic Testing for SARS-CoV-2 Infection and Future Developments: A Review

The coronavirus disease 2019 (COVID-19) caused by a novel coronavirus, SARS-CoV-2, has infected more than 50.6 million individuals and caused over 1.2 million deaths globally, raising a major health concern. To date, no specific antiviral treatment or vaccine for COVID-19 has been approved by the Food and Drug Administration (FDA). Highly sensitive and specific laboratory diagnostics are therefore critical for controlling the rapidly evolving COVID-19 pandemic and optimizing clinical care, infection control, and public health interventions. The FDA has issued emergency use authorization (EUA) for hundreds of COVID-19 diagnostic tests of different classes. Whereas nucleic acid testing (NAT) such as RT-PCR remains the criterion standard for COVID-19 diagnosis, serological antibody and antigen tests are increasingly being developed. Tests based on the novel RNA sensing techniques (e.g., SHERLOCK, DETECTR, and Toehold Switch) are promising due to their relatively low cost, high accuracy, and rapid detection time. Diagnostic testing results for SARS-CoV-2 should be interpreted with caution, since they depend heavily on factors such as viral load, virus replication, the source and timing of sample collection, sample extraction, and characteristics of various testing methods. This review aims to present the current status of common diagnostic testing for SARS-CoV-2 infection, review the current regulatory requirements, and identify future directions in the development of improved diagnostics that are more accurate, accessible, and rapid.