No, it says:

The study design does not allow us to determine whether medical masks had efficacy or whether cloth masks were detrimental to HCWs by causing an increase in infection risk. Either possibility, or a combination of both effects, could explain our results. It is also unknown whether the rates of infection observed in the cloth mask arm are the same or higher than in HCWs who do not wear a mask, as almost all participants in the control arm used a mask. The physical properties of a cloth mask, reuse, the frequency and effectiveness of cleaning, and increased moisture retention, may potentially increase the infection risk for HCWs. The virus may survive on the surface of the facemasks,29 and modelling studies have quantified the contamination levels of masks.30 Self-contamination through repeated use and improper doffing is possible. For example, a contaminated cloth mask may transfer pathogen from the mask to the bare hands of the wearer. We also showed that filtration was extremely poor (almost 0%) for the cloth masks. Observations during SARS suggested double-masking and other practices increased the risk of infection because of moisture, liquid diffusion and pathogen retention.31 These effects may be associated with cloth masks... The study suggests medical masks may be protective, but the magnitude of difference raises the possibility that cloth masks cause an increase in infection risk in HCWs.

April Coronavirus Open Thread

by Elizabeth 1 min read31st Mar 2020140 comments

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Last month’s Coronavirus Open Thread did a fantastic job at being a place for coronavirus-related information and questions that didn’t merit a top level post, but at almost 400 comments, many of which were great at the time but are now obsolete, it’s getting a little creaky. So for the next month (probably. Who knows what’s going to happen in that month) this is the new spot for comments and questions about coronavirus that don’t fit anywhere else and aren’t worth a top level post.

Wondering what happened in last month’s thread? Here are the timeless and not-yet-eclipsed-by-events highlights:

  • Spiracular on why SARS-Cov-2 is unlikely to be lab-created.
  • Two documents collating estimates of basic epidemiological parameters, in response to this thread
  • Discussion on whether the tuberculosis vaccine provides protection against COVID-19.
  • Suggestive evidence that COVID-19 removes sense of taste and smell.
  • Could copper tape be net harmful?

Want to know what’s coming up in the future? Check out the Coronavirus Research Agenda and its related questions.

Wondering why the April thread is going up on 3/31? Because everything’s a little more confusing on 4/1 and I didn’t want the extra hassle.