Funding for this research was provided by:
Wellcome Trust (WT-iTP-2018/001)
Received: 30 March 2021
Accepted: 18 August 2021
First Online: 9 September 2021
: Ethics approval was waived by the Oxford Tropical Ethics committee for this data mining exercise.
: Not applicable.
: All authors declare that they have no competing interests. Philippe Buchy is currently an employee of GSK Vaccines in Singapore but his work is unrelated to this work.