The set up..
Groups of hamsters were placed in cages with controlled one-way air flow. There were three pairs of cages; each pair consisting of adjacent cages A (COVID-infect hamsters) and B (non-infected) with air flowing in one direction (from A to B). Pair 1 had a "mask" on A and not on B. Pair 2 had a "mask" on B but not A Pair 3 had no "mask" on either
Pair 1: When mask is worn by the infected
The adjacent cage had a15% infection rate
Pair 2: When mask is worn by the uninfected
The adjacent cage had a 33% infection rate
Pair 3: When mask is worn by the none
The adjacent cage had a 66% infection rate
Conclusions..
1. Masks protect others 2. Masks offer some degree of protection to the wearer
Reusable face masks and face mask filters for Canadians