Comparison 2. Vitamin D versus placebo (sensitivity analysis excluding studies at high risk of bias).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 People with one or more study‐defined exacerbation	6	899	Odds Ratio (Random, 95% CI)	0.64 [0.34, 1.21]
2 People withdrawing from trial	7	963	Odds Ratio (M‐H, Random, 95% CI)	1.17 [0.73, 1.88]