Trial NCT05087368
Publication Costa Clemens, Open Forum Infect. Dis., 2022
Primary outcome on the report: Immune response assessed by enzyme-linked immunosorbent assay (ELISA) as immunoglobulin G antibodies against SCB-2019 S-protein on day 15... ELISA antibody titers against SCB-2019 S-protein expressed as geometric mean titers (GMTs), geometric mean-fold rise in titers over baseline (GMFR), and seroconversion rates (SCRs) on days 15 and 29. Seroconversion was defined as a≥4-fold increase in post-vaccination titer in those with a baseline titer above the lower limit of quantitation (LLOQ) or a postvaccination titer ≥4-fold the LLOQ in those with no detectable activity at baseline.

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 randomly allocated 1:1:1:1 us- ing a block size of 8 to 4 equal groups to receive a third dose of ChAdOx1-S1 or a dose of 1 of the 3 formulations of SCB-2019.”
Comment: Allocation sequence probably random.
No information on allocation concealment.
Deviations from intervention
Low 		Quote: “Study staff, investigators, and participants were masked to which vaccine had been given.”
Comment: Blinded study (participants and personnel/carers)
ITT analysis extracted. Safety analysis conducted on those who received at least one dose of the intervention.
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 low for the outcomes: Mortality. Local adverse events. Systemic adverse events. Adverse events. Serious adverse events.
Missing outcome data
Some concerns 		Comment: 120 participants randomized; 120 participants analyzed for Mortality, Adverse events and Serious adverse events; 112 participants analyzed for reactogenicity.

MORTALITY, ADVERSE EVENTS, SERIOUS ADVERSE EVENTS
Data available for all participants randomized for Confirmed severe COVID, Mortality, Adverse events and Serious adverse events.
Risk assessed to be low for the outcomes: Mortality. Adverse events.Serious adverse events.

LOCAL ADVERSE EVENTS, SYSTEMIC ADVERSE EVENTS
Data not available for all or nearly all participants randomized for reactogenicity.
No evidence that the result is not biased.
Reasons: losses to follow up, unclear.
Missingness could depend on the true value of the outcome.
Not likely that missingness depended on the true value of the outcome due to balance between groups.
Risk assessed to be some concerns for the outcomes: Local adverse events. Systemic 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 some concerns for the outcomes: Mortality. Local adverse events. Systemic adverse events. Adverse events. Serious adverse events.
Selection of the reported results
Low 		Comment: The prospective registry was available.
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 some concerns for the outcomes: Mortality. Local adverse events. Systemic adverse events. Adverse events. Serious adverse events.
Overall risk of bias
Some concerns