| Bias | Author's judgement | Support for judgement |
| Randomization |
Some concerns |
Comment: No information on allocation sequence generation or concealment methods. Imbalances in baseline characteristics are compatible with chance. |
| Deviations from intervention |
Some concerns |
Comment: Double blind trial. No deviations from the intended intervention. Trialists used ITT in the analyses of safety outcomes and per protocol in the analyses of immunogenicity. |
| Missing outcome data |
Low |
Comment: 300 randomized/300 analysed in ITT for safety outcomes. In the per protocol analysis there were 3 participants excluded (1% of the sample). No information about the reason for exclusions, however, these are not likely to have influenced the ressult. Risk assessed to be low for all the outcomes. |
| Measurement of the outcome |
Low |
Comment: Double blind study. Risk assessed to be "low" for all outcomes. |
| Selection of the reported results |
Some concerns |
Comment: Protocol and statistical plan not available. Risk assessed to be some concerns for all the outcomes. |
| Overall risk of bias |
Some concerns |