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: "Randomisation was executed using an Interactive Web Response System (IWRS). Permuted
random blocks were used, and participants were randomly assigned to the homologous or heterologous arms with equal probability. The study statistician generated the sequence and controlled access to the randomisation code. Trained staff enrolled the participants and assigned them to the trial groups."
Comment: Allocation sequence random Allocation sequence probably concealed Imbalances in baseline characteristics appear to be compatible with chance |
| Deviations from intervention |
Low |
Quote: “Pharmacists and vaccine administrators, who were aware of the treatment assignment, maintained confidentiality, loaded the vaccines in a separate cubicle, and administered them in the vaccination room. Study staff, blinded to the randomisation, were responsible for the safety evaluation of the participants following vaccination and for data analysis.”
Comment: Blinded study (participants but not personnel/carers) Deviations from intended intervention arising because of the study context: No participant cross-over. Hence, deviations did not arise because of the trial context. Safety analysis on those who received at least one dose of the intervention: As we are assessing the effect of assignment to intervention, the analysis method performed on these safety outcomes, was considered appropriate. Risk assessed to be low for the outcomes: Mortality. Serious adverse events. |
| Missing outcome data |
Low |
Comment: 405 participants randomized; 404 participants analyzed.
Data available for all or nearly all participants randomized. Risk assessed to be low for the outcomes: Mortality. Serious 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: Mortality. Serious adverse events |
| Selection of the reported results |
Low |
Comment: The prospective registry (date August 13nd, 2021) and protocol were available.
Mortality outcome was not pre-specified in the registry, however, we do not consider the reporting of this outcome to be selective since mortality should be reported even if not planned. The outcome serious adverse events was pre-specified. Results were probably not selected from multiple outcome measurements or analyses of the data. Trial analyzed as pre-specified. Risk assessed to be low for the outcomes: Mortality. Serious adverse events |
| Overall risk of bias |
Low |