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: "participants were randomized to receive either BNT162b2 (n=40) or CoronaVac (n=40) as the third dose"
Comment: Allocation sequence probably random. No information on allocation concealment. |
| Deviations from intervention |
Low |
Comment: No information on blinding (participants and 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. Intention-to-treat analysis. As we are assessing the effect of assignment to intervention, the analysis method performed was considered appropriate. Risk assessed to be low for the outcomes: Neutralizing antibody GMT. Local adverse events. Systemic adverse events. |
| Missing outcome data |
Low |
Comment: 80 participants randomized; 80 participants analyzed.
Data available for all participants randomized. Risk assessed to be low for the outcomes: Neutralizing antibody GMT. Local adverse events. Systemic 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). NEUTRALIZING ANTIBODY GMT Observer-reported outcome not involving judgement. Risk assessed to be low for the outcomes: Neutralizing antibody GMT. LOCAL and SYSTEMIC ADVERSE EVENTS 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. |
| Selection of the reported results |
Some concerns |
Comment: The protocol, statistical analysis plan, registry were available (revision dated August 17, 2021).
Outcome not pre-specified. 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 outcomes: Neutralizing antibody GMT. Local adverse events. Systemic adverse events. |
| Overall risk of bias |
Some concerns |