| Methods |
Experimental regular supplementation study in which healthy volunteers were intranasally inoculated with viruses. Duration 3 days before and 6 days after nasal instillation of virus |
| Participants |
UK adults both sexes. 47 vitamin C; 44 placebo |
| Interventions |
3 g/d vitamin C |
| Outcomes |
Shown in Table 1. Not included in meta‐analyses |
| Notes |
— |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
? |
| Allocation concealment (selection bias) |
Unclear risk |
? |
| Blinding of participants and personnel (performance bias)
All outcomes |
Unclear risk |
? |
| Blinding of outcome assessment (detection bias)
All outcomes |
Unclear risk |
? |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Laboratory study |
| Vitamin C and placebo indistinguishable? |
Unclear risk |
? |
