Quantitative errors in the Cochrane review on "Physical interventions to interrupt or reduce the spread of respiratory viruses" (27 October 2023)

Summary

The Covid-19 pandemic increased the sense of urgency to advance understanding and prevention of infectious respiratory disease transmission. There are extensive studies that demonstrate scientific understanding about the behaviour of larger (droplets) and smaller (aerosols) particles in disease transmission as well as the presence of particles in the respiratory track.

Methods for respiratory protection against particles, such as N95 respirators, are available and known to be effective with tested standards for harm reduction. However, even though multiple studies also confirm their protective effect when N95 respirators are adopted in healthcare and public settings for infection prevention, overall, studies of protocols of their adoption over the last several decades have not provided a clear understanding. This preprint article demonstrates limitations in the methodology used to analyse the results of these studies. The authors show that existing results, when outcome measures are properly analysed, consistently point to the benefit of precautionary measures such as N95 respirators over medical masks, and masking over its absence.