. 2020 Mar 2;7:e7. doi: 10.1017/gmh.2020.1
© The Author(s) 2020
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
Fig. 2.
PRISMA flow diagram.