Correction to: Nature Protocols, published online 23 September 2019.

In the version of this article initially published, three of the sensitivity values in the bottom table in Box 1 were incorrect. The value for LwaCas13a should have been 5e7 aM, not ~5e5 aM; the value for CcaCas13b should have been ~5e7 aM, not ~5e6 aM; and the value for PsmCas13b should have been ~5e9 aM, not ~5e8 aM. In addition, the ‘Anticipated results’ section should not have mentioned Fig. 1d; Fig. 1 has no panel d. The errors have been corrected in the HTML and PDF versions of the article.