Study registration: *
Publication Lopez Bernal J, BMJ, 2021
Dates: 2020-10-26 to 2021-02-21
Funding: Public/non profit (There was no external funding for this study. Funded by Public Health England)
Conflict of interest: no COI (All authors have completed the ICMJE uniform disclosure form at and declare: funding from Public Health England for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years, no other relationships or activities that could appear to have influenced the submitted work.)