September 4, 2023. A Systematic Review of the Physical Measures to Reduce the Spread of Respiratory Viruses
This article, published in January 2023, in the Cochrane Database of Systematic Reviews shows a systematic review of 78 randomized controlled trials (RCT) that compare the use of surgical masks, N95 respirators and hand hygiene. More than 600,000 participants were included.
Surgical Masks vs No Mask in the Community and Hospitals
Risk ratio (RR) 0.95, 95% confidence interval (CI) 0.84 to 1.09.
This means that there is no statistical difference between using a surgical mask and not using a mask.
N95 Respirators vs Surgical Masks in Households and Hospitals
RR 0.70, 95% CI 0.45 to 1.10
This means that N95 respirators are not much better that surgical masks. Here I may add that a N95 respirator used correctly, after adequate fitting and single (per patient) use may still have an advantage over surgical masks.
Hand Hygiene Interventions vs Controls
RR 0.86, 95% CI 0.81 to 0.90.
This means that hand hygiene interventions do have statistically significant protective effect.