Funding for this research was provided by:
Wellcome Trust (221303/Z/20/Z, 221303/Z/20/Z, 221303/Z/20/Z)
Received: 26 April 2020
Accepted: 22 September 2020
First Online: 14 October 2020
Ethics approval and consent to participate
: The study used only publicly available aggregate data and was thus not subject to ethical review.
: Not applicable.
: The authors declare that they have no competing interests.