Bias | Author's judgement | Support for judgement |
Randomization |
Some concerns |
Quote: "Participants were assigned a study number at enrolment and vaccinated according to a randomisation list prepared by the study sponsor" Comment: Unclear allocation sequence and allocation concealment. |
Deviations from intervention |
Low |
Quote: "All participants and personnel involved in safety data collection and immunogenicity assessments were blinded to the study treatment. Vaccine preparation and administration were performed by different unblinded study personnel, using opacified syringes to maintain the participant blind as the vaccine and placebo are visually different." (report) "Masking: Triple (Participant, Investigator, Outcomes Assessor)" (trial registry) Comment: Blinded study (patients and investigators). No participant cross-over. As we are assessing the effect of assignment to intervention, the intention-to-treat analysis method performed on these outcomes, was considered appropriate. Risk assessed to be low for all outcomes. |
Missing outcome data |
Low |
Comment: 151 patients randomized; 150 patients analyzed for safety, 146 for immunogenicity. Data available for >95% of population. Risk assessed to be low for the outcomes: Confirmed COVID. Confirmed symptomatic COVID. Hospitalization or death due to COVID. Mortality. Specific antibody seroconversion and GMTs. Neutralizing antibody seroconversion and GMTs. Withdrawals due to adverse events. |
Measurement of the outcome |
Low |
Quote: "All participants and personnel involved in safety data collection and immunogenicity assessments were blinded to the study treatment" Comment: Blinded study (outcome assessor). Risk assessed to be low for the outcomes: Confirmed COVID. Confirmed symptomatic COVID. Hospitalization or death due to COVID. Mortality. Specific antibody seroconversion and GMTs. Neutralizing antibody seroconversion and GMTs. Withdrawals due to adverse events. |
Selection of the reported results |
Low |
Comment: The trial registry was 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: Confirmed COVID. Confirmed symptomatic COVID. Hospitalization or death due to COVID. Mortality. Specific antibody seroconversion and GMTs. Neutralizing antibody seroconversion and GMTs. Withdrawals due to adverse events. |
Overall risk of bias |
Some concerns |