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: "Randomization of eligible individuals approved for participation took place successively between May 20 and May 25, 2020."
Comment: Allocation sequence probably random. No information on allocation concealment. Limited baseline data provided to examine imbalances at randomization. There are more participants in the 61-65 years age group in the control arm compared to the intervention arm. |
| Deviations from intervention |
Some concerns |
Quote: “open label”(registry).
Comment: Unblinded study (participants and personnel/carers). Deviations from intended intervention arising because of the study context: 18% of participants randomized to the intervention group never accessed the training facilities. There was no information on whether control participants crossed over to the training arm. No co-interventions of interest (vaccines) available at time of study. Hence, no information (or not enough information) on whether deviations arose because of the trial context. < Participants were analyzed according to their randomized groups for the outcome. Of note, 214 vs 534 participants were excluded from the analysis post-randomization due to missing data which is accounted for in domain 3. This method was considered appropriate to estimate the effect of assignment to intervention for this outcome. Risk assessed to be some concerns for the outcome: Confirmed COVID-19. |
| Missing outcome data |
High |
Comment: 3764 participants randomized; 3016 participants analyzed.
Data not available for all or nearly all participants randomized. No evidence that the result is not biased. Reasons for missing data: Did not perform the test (214/1896 vs 534/1868). Missingness could depend on the true value of the outcome. Likely that missingness depended on the true value of the outcome (unequal proportion of missingness between arms) Risk assessed to be high for the outcome: Confirmed COVID-19. |
| Measurement of the outcome |
Low |
Quote: "open label” (registry).
Comment: Method of measuring the outcome probably appropriate. Measurement or ascertainment of outcome probably does not differ between groups. Unblinded study (outcome assessor) PCR-confirmed status is an observer-reported outcome not involving judgement. Risk assessed to be low for outcome: Confirmed COVID-19. |
| Selection of the reported results |
Low |
Comment: The protocol and statistical analysis plan were not available. An early version of the trial registry (dated May 27th, 2020) was accessible and consulted.
Outcome 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 outcome: Confirmed COVID-19. |
| Overall risk of bias |
High |