An accompanying smartphone app analyzes the fluorescent readout generated by the assay, giving users a clear “Positive” or “Negative” result. The results can also be shared with doctors and health organizations to track a disease’s spread. (Credit: Wyss Institute at Harvard University)

Despite the impressively fast development of SARS-CoV-2 diagnostic tests over the last year and a half, the vast majority of patient samples must still be sent to a lab for processing, which slows down the pace of COVID-19 case tracking. Now a CRISPR-based diagnostic test allows users to test themselves for SARS-CoV-2 and multiple variants of the virus using a sample of their saliva at home, with no extra instrumentation needed.

The diagnostic device, called Minimally Instrumented SHERLOCK (miSHERLOCK), is easy to use and provides results that can be read and verified by an accompanying smartphone app within one hour. It successfully distinguished between three different variants of SARS-CoV-2 in experiments and can be rapidly reconfigured to detect additional variants like Delta.

The technology makes use of CRISPR’s “molecular scissors” to snip DNA or RNA at specific locations, with an added bonus: upon recognizing its target sequence, this specific type of scissors also cuts other pieces of DNA in the surrounding area, allowing it to be engineered to produce a signal indicating that the target has been successfully cut.

The device can be assembled using a 3D printer and commonly available components for about $15, and re-using the hardware brings the cost of individual assays down to $6 each.