a, Genome map showing primers, probes and gRNAs. Visualization of primers and probes on the SARS-CoV-2 genome. RT–LAMP primers are indicated by black rectangles, the binding position of the F1c and B1c half of the forward inner primer (FIP) (gray) is represented by a striped rectangle with dashed borders. b, gRNA specificity. Cas12 gRNAs are programmed to specifically target SARS-CoV-2 or broadly detect related coronavirus strains. The N gene gRNA used in the assay (left) was specific for SARS-CoV-2, whereas the E gene gRNA was able to detect three SARS-like coronavirus strains (right). A separate N gene gRNA designed to target SARS-CoV and a bat coronavirus failed to detect SARS-CoV-2 (middle). c, The minimum equipment needed to run the protocol. With appropriate biosafety level 2 requirements, the minimum equipment required to run the protocol following RNA extraction includes Eppendorf tubes with reagents, heat blocks or water bath (37 °C and 62 °C), nuclease-free water, pipettes and tips and lateral flow strips. d, Schematic of SARS-CoV-2 DETECTR workflow. Conventional RNA extraction can be used as an input to DETECTR (LAMP preamplification and Cas12-based detection for E gene, N gene and RNase P), which is visualized by a fluorescent reader or lateral flow strip. e, Lateral flow strip assay readout. A positive result requires detection of at least one of the two SARS-CoV-2 viral gene targets (N gene or E gene, as indicated in the interpretation matrix). QC, quality control.