In the race to engineer rapid testing systems for COVID-19 diagnosis, researchers in California have developed an assay that requires no complex equipment and returns results in under one hour.

The SARS-CoV-2 DETECTR protocol devised by collaborators from Mammoth Biosciences, University of California San Francisco and California Department of Public Health is one of the first tests to use CRISPR (clustered regularly interspaced short palindromic repeats) gene-targeting to detect the novel coronavirus. The assay monitors for the presence of two specific regions in the novel coronavirus genome, one of which is common to all SARS-like coronaviruses and one unique to the SARS-CoV-2 agent responsible for COVID-19. This helps to differentiate COVID-19 infections from those caused by other coronaviruses.

The rapid test outlined in Nature Biotechnology can be performed in any lab using off-the-shelf reagents and is sufficiently sensitive to detect the presence of as few as 10 coronaviruses in a microliter of fluid samples. While slightly less sensitive than available polymerase chain reaction-based tests, the difference is unlikely to have a major impact on diagnosis, due to the high viral loads of infected patients.

The method has been validated using reference and clinical samples from patients and is in the pipeline for fast-track approval through an Emergency Use Authorization from the U.S. Food and Drug Administration.

Schematic of SARS-CoV-2 DETECTR workflow. Source: James P. Broughton et al.