Risk of bias for analysis 4.1 Infection with SARS‐CoV‐2 by day 30.

Study

Bias

Randomisation process

Deviations from intended interventions

Missing outcome data

Measurement of the outcome

Selection of the reported results

Overall

Authors' judgement

Support for judgement

Authors' judgement

Support for judgement

Authors' judgement

Support for judgement

Authors' judgement

Support for judgement

Authors' judgement

Support for judgement

Authors' judgement

Support for judgement

O'Brien 2021

Low risk of bias

Participants were randomised via an Interactive Web Response System (IWRS) and the allocation sequence was concealed. There are no baseline differences that would suggest a problem with randomisation.

Low risk of bias

Both participants and those delivering the intervention were unaware of the assigned intervention received, and the analysis was appropriate.

Low risk of bias

Data for this outcome was available for all participants SARS‐CoV‐2 RT‐PCR and serology negative at baseline (753 treatment group and 752 placebo group randomised and analysed).

Low risk of bias

The measurement of the outcome was appropriate, and it is unlikely that it differed between intervention groups. The outcome assessors were unaware of the intervention received.

Low risk of bias

The data that produced this result was analysed in accordance with the pre‐specified analysis plan and the outcome was reported as planned in the protocol.

Low risk of bias

For this outcome, there is a low risk of bias for all the domains.