This piece suggests infection can be caused by a person with Covid-19 merely breathing within a 2 metre radius.

As evidence it cites a letter that lists an assortment of studies that found genetic material from coronaviruses in places that imply travel in aerosols. 1/n https://twitter.com/PaulGlasziou/status/1247758465025490945

This piece, written with colleagues, notes that those studies do not even attempt to answer the crucial 'enough questions' —

- enough virus in droplets?
- enough droplets in volume of air?
- enough infectious potential in virus? https://insidestory.org.au/so-you-want-to-wear-a-mask-in-public/

Without answering those questions, it's purely speculation to claim that SARS-CoV-2 is capable of airborne transmission.

But that one term—airborne—provokes SIGNIFICANT alarm in the general public and can motivate highly counterproductive behaviours.

So what other evidence could we draw on?

Glasziou and Del Mar are outspoken advocates of evidence based medicine — relying on RCTs and systematic reviews to challenge long-standing traditional practices in medicine. But RCTs are not the only reliable sources of knowledge.

In our piece we review the experience in China, informed by aggressive contact tracing of 80K+ cases, supplemented by studies of localised incidence, and phylogenetic analyses. They don't support the hypothesis of airborne transmission nor infection via brief, casual contact.

If we're doing public information we need to understand that we're intervening in an existing discourse, with multiple actors, voices, standpoints, and circulating claims.

The argument for masks walks back one key, solid bit of knowledge: that SARS2 is droplet transmitted.

Understanding that key fact is vital for maintaining high adherence to recommendations on hand-washing, avoiding facial touching, avoiding common surfaces, and maintaining physical separation. And to preventing a run on PPE that could leave healthcare workers without protection.