. Author manuscript; available in PMC: 2019 Mar 1.
Published in final edited form as: Sex Transm Infect. 2017 Sep 2;94(2):131–137. doi: 10.1136/sextrans-2017-053235
The Corresponding Author has the right to grant on behalf of all authors and does grant on behalf of all authors, an exclusive licence (or non exclusive for government employees) on a worldwide basis to the BMJ Publishing Group Ltd to permit this article (if accepted) to be published in STI and any other BMJPGL products and sub-licences such use and exploit all subsidiary rights, as set out in our licence http://group.bmj.com/products/journals/instructions-for-authors/licence-forms.