Table 3.

Outcomes for mask use to prevent viral respiratory tract infections

MASK USERSCONFIRMED INFLUENZACONFIRMED VIRALINFLUENZALIKE ILLNESSANY RESPIRATORY INFECTION
RCTS (N*)RR (95% CI)RCTS (N*)RR (95% CI)RCTS (N*)RR (95% CI)RCTS (N*)RR (95% CI)
Community
  • Community members2 (1683)0.93 (0.50–1.75)0 (0)NA2 (1683)0.83 (0.69–0.99)0 (0)NA
  • Families—sick wearing masks0 (0)NA1 (597)0.98 (0.06–15.54)2 (794)0.89 (0.48–1.66)1 (597)0.65 (0.19–2.28)
  • Families—healthy wearing masks1 (220)2.18 (0.25-19.16)1 (220)2.96 (0.67–13.02)1‡ (220)1.17 (0.62–2.18)0 (0)NA
  • Families—healthy and sick wearing masks4 (1168)0.95 (0.71–1.26)0 (0)NA4 (1377)1.09 (0.86–1.37)0 (0)NA
  • Communities staying in tents1 (2317)1.24 (0.33–4.59)2 (2386)1.18 (0.79–1.78)1 (69)0.56 (0.29–1.08)1 (1810)1.08 (0.83–1.40)
  • Families—given masks before illness0 (0)NA0 (0)NA1 (789)0.90 (0.60–1.34)0 (0)NA
Health care workers
  • Masks vs nothing1 (431)Not estimable1 (431)0.90 (0.33–2.44)1 (431)0.26 (0.01–6.42)2 (463)0.74 (0.36–1.54)
  • N95 masks vs surgical masks4§ (6039)1.10 (0.91–1.32)4§ (6059)0.95 (0.83–1.07)4§ (6662)0.78 (0.61–1.00)3§ (5033)0.95 (0.90–1.00)
  • Surgical masks vs cloth masks1 (717)0.98 (0.06–15.62)1 (717)0.62 (0.31–1.26)1 (717)0.12 (0.02–0.98)1 (717)0.62 (0.34–1.11)
  • NA—not applicable, RCT—randomized controlled trial, RR—risk ratio.

  • * The number of patients is modified (reduced) to account for clustering.

  • Results calculated using a fixed-effects model.

  • One RCT had 2 arms.

  • § Two of the included RCTs had 2 arms, so 4 RCTs would be 6 arms and 3 RCTs would be 5 arms.