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: "91 participants were randomised"
Comment: Allocation sequence probably random. No information on allocation concealment. |
| Deviations from intervention |
Some concerns |
Comment: Unclear blinding, no information on blinding was reported but blinding was unlikely as two arms received intramuscular injections and the third intradermal.
Deviations from intended intervention arising because of the study context: Unclear whether there was any participant cross-over. Hence, no information on whether deviations arose because of the trial context. Intention-to-treat analysis. 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: Local adverse events. Systemic adverse events. Serious adverse events. |
| Missing outcome data |
Low |
Comment: 91 participants randomized; 91 participants analyzed.
Data available for all participants randomized. Risk assessed to be low for the outcomes: Local adverse events. Systemic adverse events. Serious adverse events. |
| Measurement of the outcome |
Some concerns |
Comment: Method of measuring the outcome probably appropriate.
Measurement or ascertainment of outcome probably does not differ between groups. Unclear blinding (outcome assessor). The authors reported on adverse events that may contain both clinically- and laboratory-detected events, which can be influenced by knowledge of the intervention assignment, but is not likely in the context of the pandemic. Risk assessed to be some concerns for the outcomes: Local adverse events. Systemic adverse events. Serious adverse events. |
| Selection of the reported results |
Some concerns |
Comment: The registry was retrospective (dated 2 October 2021).
No information on whether the result was selected from multiple outcome measurements or analyses of the data. No information on whether the trial was analyzed as pre-specified. Risk assessed to be some concerns for the outcomes: Local adverse events. Systemic adverse events. Serious adverse events. |
| Overall risk of bias |
Some concerns |