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 randomized in a ratio of 1:1:1 to receive the low-dose BNT126b1 or high-dose BNT126b1 or placebo. Participants were stratified by gender, using a Web-based interactive response technology (IRT) system. The blocked randomization list was generated by an independent statistician.” Comment: Allocation sequence random. Allocation sequence concealed. |
| Deviations from intervention |
Some concerns |
Quote: "single blind"; "The trial staff administering the vaccine prepared vaccines out of sight of the participants and syringes were covered with an opaque material until ready for administration to ensure masking of participants."
Comment: Two single blind studies (participants only) No participant cross-over. SAFETY Intention to treat analysis was performed on the dafety outcomes. As we are assessing the effect of assignment to intervention, this analysis method was considered appropriate. Risk assessed to be low for outcomes: Severe COVID. Hospital admissions or death due to confirmed COVID. Mortality. Adverse events. Serious adverse events. EFFICACY Per-protocol analysis was performed on the efficacy outcomes (as planned in the trial protocol). Reasons for exclusions: Baseline seropositivity results unavailable; Baseline seropositivity results positive; Vaccine administration errors; Less than 15 days of follow up accrued post second dose; PCR+ test 14 days post-second dose As we are assessing the effect of assignment to intervention (intent-to-treat effect), this domain was evaluated as some concerns for efficacy outcomes. Risk assessed to be some concerns for outcomes: Confirmed COVID. Confirmed symptomatic COVID. |
| Missing outcome data |
Low |
Comment: 144 patients randomized; 142 patients analyzed. Data available for >95% of population. Risk assessed to be low for the outcomes: Local adverse events. Systemic adverse events. Adverse events. Withdrawal due to adverse events. Serious adverse events. |
| Measurement of the outcome |
Low |
Comment: Blinded study (outcome assessor). Risk assessed to be low for the outcomes: Local adverse events. Systemic adverse events. Adverse events. Withdrawal due to adverse events. Serious adverse events. |
| Selection of the reported results |
Low |
Comment: The trial registries were available. 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: . Local adverse events. Systemic adverse events. Adverse events. Withdrawal due to adverse events. Serious adverse events. |
| Overall risk of bias |
Low |