Correction to: Nature Medicine https://doi.org/10.1038/s41591-020-0886-4, published online 8 June 2020.

In the version of this article initially published, the units used for TEER results (ohm cm–2) were incorrect in the third, fourth, fifth and final sentences of the fourth paragraph in the first subsection of Results; along the vertical axis of Fig. 1k; and in the fourth sentence of the second subsection of Methods (‘iBBB permeability studies’). The correct units are ‘ohm cm2’. The error has been corrected in the HTML and PDF versions of the article.