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: "Allocation (randomization) of participants to vaccine groups will proceed using an IRT system (IWR). The site personnel (study coordinator or specified designee) will be required to enter or select information including but not limited to the user’s ID and password, the protocol number, and the participant number. The site personnel will then be provided with a vaccine assignment and randomization number. The IRT system will provide a confirmation report containing the participant number, randomization number, and study intervention allocation assigned. The confirmation report must be stored in the site’s files."
Comment: Allocation sequence random Allocation sequence concealed |
| Deviations from intervention |
Some concerns |
Quote: “Study staff receiving, storing, dispensing, preparing, and administering the
study interventions were unblinded. All other study and site
personnel, including the investigator, investigator staff, and par-
ticipants, were blinded to study intervention assignments.”
Comment: Blinded study (participants and personnel/carers) Per-protocol analysis was performed on the outcomes. No reasons for exclusion reported. As we are assessing the effect of assignment to intervention (intention-to-treat effect), we considered that the data were analyzed inappropriately. There was probably no substantial impact of failure to analyze participants according to their randomized assignment. Risk assessed to be some concerns for the outcomes:specific Ab GMT, specific Ab GMT (>90 days), neutralizing antibody assay, neutralizing antibody assay (>90 days), neutralizing antibody assay Omicron, neutralizing antibody assay Omicron (>90 days). |
| Missing outcome data |
Some concerns |
Comment: 123 participants randomized; from 93 to 117 participants analyzed.
Data not available for all or nearly all participants randomized. No evidence that the result is not biased. Reasons for missigness not reported Missingness could depend on the true value of the outcome. Not likely that missingness depended on the true value of the outcome Risk assessed to be some concerns for the outcomes:specific Ab GMT, specific Ab GMT (>90 days), neutralizing antibody assay, neutralizing antibody assay (>90 days), neutralizing antibody assay Omicron, neutralizing antibody assay Omicron (>90 days). |
| 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:specific Ab GMT, specific Ab GMT (>90 days), neutralizing antibody assay, neutralizing antibody assay (>90 days), neutralizing antibody assay Omicron, neutralizing antibody assay Omicron (>90 days). |
| Selection of the reported results |
Some concerns |
Comment: The prospective registry was available (dated July 9, 2021)
SPECIFIC ANTIBODY GMT, SPECIFIC ANTIBODY GMT (>90 days) Outcome not pre-specified [Specify the scenario encountered. That was an example] 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:specific Ab GMT, specific Ab GMT (>90 days). NEUTRALIZING ANTIBODY ASSAY, NEUTRALIZING ANTIBODY ASSAY (>90 days), NEUTRALIZING ANTIBODY ASSAY OMICRON, NEUTRALIZING ANTIBODY ASSAY OMICRON (>90 days) Outcomes 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 outcomes: neutralizing antibody assay, neutralizing antibody assay (>90 days), neutralizing antibody assay Omicron, neutralizing antibody assay Omicron (>90 days). |
| Overall risk of bias |
Some concerns |