Nat. Biotechnol. 26, 256 (2008); published online 7 March 2008; corrected after print 11 July 2008

In the version of this article initially published, the author reported that “trial participants now test seropositive for HIV and are 'unable to convince their employers that their HIV status was vaccine induced'.” In fact, none of the trial participants tested positive for HIV. The error has been corrected in the HTML and PDF versions of the article.