Uptake and effectiveness of facemask against respiratory infections at mass gatherings: a systematic review.

In regards to the effectiveness of facemask, four out of thirteen studies demonstrated significant effect against respiratory infections, 18 , 20 , 22 , 28 two others showed some effect but did not reach statistical significance. 25 , 26 One study assessed its effectiveness against fever but ruled out its protectiveness, 39 and the other six studies did not show effectiveness but results were not statistically significant. 24 , 30 , 31 , 32 , 37 , 40 The pooled data from all studies revealed significant protectiveness of facemasks against respiratory infections in general at Hajj (relative risk [RR] = 0.89, 95% CI: 0.84-0.94, p < 0.01) ( Table 2 ).

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