Summary of findings 2. N95 respirators compared to medical/surgical masks for preventing the spread of viral respiratory illness.
| Randomised studies: N95 respirators compared to medical/surgical masks for preventing the spread of viral respiratory illness | ||||||
| Patient or population: general population and healthcare workers Setting: hospitals and households Intervention: N95 masks Comparison: medical/surgical masks | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with medical masks | Risk with randomised studies: N95 | |||||
| Viral respiratory illness ‐ clinical respiratory illness | Study population | RR 0.70 (0.45 to 1.10) | 7799 (3 RCTs) | ⊕⊝⊝⊝ Very Lowa,b,c | All studies were conducted in hospital settings with healthcare workers. | |
| 120 per 1000 | 84 per 1000 (54 to 132) | |||||
| Viral respiratory illness ‐ influenza‐like illness | Study population | RR 0.82 (0.66 to 1.03) | 8407 (5 RCTs) | ⊕⊕⊝⊝ Lowa,b | 1 study was conducted in households (MacIntyre 2009). | |
| 50 per 1000 | 41 per 1000 (33 to 52) | |||||
| Viral respiratory illness ‐ laboratory‐confirmed influenza | Study population | RR 1.10 (0.90 to 1.34) | 8407 (5 RCTs) | ⊕⊕⊕⊝ Moderateb | 1 study was conducted in households (MacIntyre 2009). | |
| 70 per 1000 | 77 per 1000 (63 to 94) | |||||
| Adverse events | ‐ |
‐ | (5 RCTs) | ⊕⊝⊝⊝ Very Lowa,b,c | There was insufficient consistent reporting of adverse events to enable meta‐analysis. Only 1 study reported detailed adverse events: discomfort was reported in 41.9% of N95 wearers versus 9.8% of medical mask wearers (P < 0.001); headaches were more common with N95 (13.4% versus 3.9%; P < 0.001); difficulty breathing was reported more often in the N95 group (19.4% versus 12.5%; P = 0.01); and N95 caused more problems with pressure on the nose (52.2% versus 11.0%; P < 0.001). 4 RCTs either reported no adverse events or only reported on comfort wearing masks. |
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| *The risk in the intervention group (and its 95% confidence interval) is based on the median risk in the comparison group and the observed relative effect of the intervention (and its 95% CI). CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect. | ||||||
aDowngraded one level for study limitations (lack of blinding). bDowngraded one level for imprecision (wide confidence interval or no meta‐analysis conducted). cDowngraded one level for inconsistency of results (heterogeneity).