Note: The risk of bias by domain corresponds to the highest risk of bias among outcomes by domain.
The overall risk of bias corresponds to the overall highest risk of bias assessed among outcomes.
| Bias | Author's judgement | Support for judgement |
| Randomization |
Low |
Quote: "Participants were sequentially assigned a randomisation number generated by an independent statistician using Stata, version 12.0, and stratified block randomisation (block size eight) by subgroups was adopted. All vaccines used for inoculation were distributed in identical packages with serial numbers to ensure masking of participants"
Comment: Allocation sequence random random. Allocation sequence concealed. Imbalances in baseline characteristics appear to be compatible with chance. |
| Deviations from intervention |
Low |
Quote: "Group allocation was masked from participants, investigators, and outcome assessors for the duration of the study"
Comment: Blinded study (participants and personnel/carers). ITT analysis (with N randomized denominators) was reported for immunogenicity; and safety analysis was on those who received at least one dose of the intervention. As we are assessing the effect of assignment to intervention, the analysis methods performed on these outcomes were considered appropriate. Risk assessed to be low for the outcomes: Neutralizing antibody GMT. Local adverse events. Systemic adverse events. Adverse events. |
| Missing outcome data |
Low |
Comment: 1008 participants randomized; 1007 participants analyzed.
Data available for nearly all participants randomized. Risk assessed to be low for the outcomes: Neutralizing antibody GMT. Local adverse events. Systemic adverse events. Adverse events. |
| Measurement of the outcome |
Low |
Comment: Method of measuring the outcome probably appropriate.
Measurement or ascertainment of outcome probably does not differ between groups. Blinded study (outcome assessor). Risk assessed to be low for the outcomes: Neutralizing antibody GMT. Local adverse events. Systemic adverse events. Adverse events. |
| Selection of the reported results |
Low |
Comment: The prospective registry was available (dated 29 April 2020).
Outcome pre-specified. Results were not selected from multiple outcome measurements or analyses of the data. Trial analyzed as pre-specified. Risk assessed to be low for the outcomes: Neutralizing antibody GMT. Local adverse events. Systemic adverse events. Adverse events. |
| Overall risk of bias |
Low |