They work folks! #Masks4All https://twitter.com/EricTopol/status/1246048594672537606

BUT! It's worth keeping in mind (especially in everyday use and with non-sterile ones) that masks may not work to protect you, but rather to protect others from you and your viral shedding - especially if you're an asymptomatic carrier.
https://twitter.com/EggerFelix/status/1246057605409189893?s=2

And it turns out that shit/shed loads of people can be infected with COVID-19 and asymptomatic - though not forever. As both the Diamond Princess and Iceland testing has shown those infected may turn out to have been presymptomatic, at time of testing. https://twitter.com/cmyeaton/status/1246196001775460358?s=20

And this thread breaks down the difference between the likely hood/situationally of you protecting yourself versus protecting others - with officialised words like 'receiver protection' (harder to do right) and 'source control' (easier to do). https://twitter.com/CT_Bergstrom/status/1246013181551493120?s=20