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: ""Eligible participants were randomly assigned (1:1) to
ZyCoV-D vaccine or placebo using a randomisation
schedule generated using SAS software (version 9.4 or
higher) with the help of an interactive web response
systems (IWRS). The IWRS was used for randomisation
(blocks of four) of participants as well as to enrol individuals
aged 60 years and older with or without comorbid
conditions, and those aged 12–17 years. It was also used to
identify 600 participants for immunogenicity (blocks of six).
Investigators at sites received random allocation
information through the IWRS. The randomisation
sequence was generated by an independent statistician
using SAS and fed into the IWRS. Participants were
enrolled by investigators with the help of the IWRS""
Comment: Allocation sequence random Allocation sequence concealed Imbalances in baseline characteristics appear to be compatible with chance" |
| Deviations from intervention |
Some concerns |
"Quote: Double-blind. “The statisticians who conducted randomization were not involved in other work relevant to this clinical trial. The trial participants, field investigators, and nurses who administrated the vaccine or placebo were unaware of the trial-group assignments during the trial.” Comment: Blinded study (participants and personnel/carers) Efficacy anlaysis on those who had undergone randomization and completed the three-dose regimen. Reasons for exclusion: received another vaccine (31 vs 30), protocol violations (3 vs 2), had confirmed covided between dose 1 and 7 days after dose 3( 27 VS 46). As we are assessing the effect of assignment to intervention (intention-to-treat effect), we considered that the data were analyzed inappropriately. Probably no substantial impact of failure to analyze participants according to their randomized assignment due to balance between groups. Risk assessed to be some concerns for the outcomes: Confirmed symptomatic COVID. |
| Missing outcome data |
Some concerns |
Comment: 28904 participants randomized; 25193 participants analyzed for efficacy
EFFICAY AGAINST VARIANTS Variant sequence: 738 cases identified/ 626 cases sequenced 84.8% of cases analyzed for variants. Risk assessed to be some concerns for the outcome: Confirmed symptomatic against Delta variant. |
| Measurement of the outcome |
|
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: Confirmed symptomatic COVID. |
| Selection of the reported results |
Low |
Comment: The protocol (25 Oct 2020), statistical analysis plan (2 Aug 2021) and registry (30 Nov 2020) were available. Outcomes pre-specified in registry, protocol and/or statistical analysis plan. Trial analyzed as pre-specified. Risk assessed to be low for the outcomes: Confirmed symptomatic COVID. |
| Overall risk of bias |
Some concerns |