Illustration from WSJ article
Face coverings for the public: Laying straw men to rest
Funding information: National Institute for Health Research, Grant/Award Number: BRC‐1215‐20008; Wellcome Trust, Grant/Award Number: WT104830MA
This scholarly article by an experienced doctor and science writer, is well worth reading.
Excerpt: … In relation to a community‐wide intervention such as face coverings, we do not need to prevent every transmission of every droplet or every viral particle. As with hand‐washing and social distancing, the objective of the policy is more modest: to achieve a substantial reduction in the transmission rate of the virus. Every infectious disease has a transmission rate (R0). A disease with an R0 of 1.0 means that each infected person, on average, infects one other person. A disease whose R0 is less than 1.0 will die out. The strain of flu that caused the 1918 pandemic had an R0 of 1.8. The R0 of Sars‐CoV‐2 was estimated at 2.4 by Imperial College researchers,24 and other research suggests it could even higher.25 A population measure that reduces the transmission rate (“effective R0” or Reff) to below 1.0 will be highly effective, even if some cases of transmission still occur .
Particularly those with several layers of cotton cloth
- May 26, 2020
- McMaster University
- Researchers examined a century of evidence including recent data, and found strong evidence showing that cloth and cloth masks can reduce contamination of air and surfaces. MORE
The science around the use of masks by the general public to impede COVID-19 transmission is advancing rapidly. Policymakers need guidance on how masks should be used by the general population to combat the COVID-19 pandemic. Here, we synthesize the relevant literature to inform multiple areas: 1) transmission characteristics of COVID-19, 2) filtering characteristics and efficacy of masks, 3) estimated population impacts of widespread community mask use, and 4) sociological considerations for policies concerning mask-wearing. A primary route of transmission of COVID-19 is likely via small respiratory droplets, and is known to be transmissible from presymptomatic and asymptomatic individuals. Reducing disease spread requires two things: first, limit contacts of infected individuals via physical distancing and contact tracing with appropriate quarantine, and second, reduce the transmission probability per contact by wearing masks in public, among other measures. The preponderance of evidence indicates that mask wearing reduces the transmissibility per contact by reducing transmission of infected droplets in both laboratory and clinical contexts. Public mask wearing is most effective at stopping spread of the virus when compliance is high. The decreased transmissibility could substantially reduce the death toll and economic impact while the cost of the intervention is low. Thus we recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies. We recommend that public officials and governments strongly encourage the use of widespread face masks in public, including the use of appropriate regulation.