Do cloth masks help stop the spread of COVID-19?

They do not block individual virus particles, but most virions spread in aerosols or larger droplets, Canadian researchers point out

Cloth masks may help prevent transmission of the SARS-CoV-2 virus by at least partially blocking droplets expelled by people when they speak, cough and sneeze, researchers say.

While the weave of cloth masks may not be tight enough to block individual virus particles, most virions spread in aerosols (smaller than 5 micrometers) or larger droplets, Canadian authors write in the Annals of Internal Medicine.

And there is ample evidence that the masks can prevent