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 |
Some concerns |
Quote: "The principal investigator appointed a study drug randomization supervisor who prepared the randomization schedule prior to participant enrolment and was responsible for storing and managing it until study unblinding." Quote: "The principal investigator assigned unblinded medical staff in advance who allocated, prepared and administered the study drugs and were not involved in the assessments of participants after administration."
Comment: Allocation probably random. Unclear allocation concealment. |
| Deviations from intervention |
Some concerns |
Quote: “Assessors and participants were blinded for the study. The principal investigator assigned unblinded medical staff in advance who allocated, prepared and administered the study drugs and were not involved in the assessments of participants after administration.” Comment: Unblinded study (participants blinded, personnel/carers unblinded) Deviations from intended intervention arising because of the study context: 12 participants received other authorized COVID-19 vaccines (3 vs 4 vs 1 vs 1 vs 3). This deviation was not balanced and could affect the outcome. Nevertheless, this domain was rated as some concern as it is impossible to distinguish deviation because of trial context and deviation because of intervention effect. ITT analysis (with N randomized denominators) 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 some concerns for the outcomes: Adverse events. Serious adverse events. |
| Missing outcome data |
Low |
Comment: 46 participants randomized; 46 participants analyzed.
Data available for all or nearly all participants randomized. Risk assessed to be low for the outcomes: Adverse events. 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: Adverse events. Serious adverse events. |
| Selection of the reported results |
Low |
Comment: The restrospective protocol and statistical analysis plan (May 13,2022), and the prospective registry were available (dated Feb. 01, 2022)
ADVERSE EVENTS 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 outcome: Adverse events. SERIOUS ADVERSE EVENTS Outcome not pre-specified in the prospective registry and no prospective protocol available No information on whether the result was selected from multiple outcome measurements or analyses of the data. Trial not analyzed as pre-specified. Risk assessed to be some concerns for the outcome: Serious adverse events. |
| Overall risk of bias |
Some concerns |